Adding upstream version 3.1.7.upstream/3.1.7upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

9 files changed, 4606 insertions, 0 deletions

diff --git a/tests/pool/__init__.py b/tests/pool/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/tests/pool/__init__.py
diff --git a/tests/pool/fix_pool.py b/tests/pool/fix_pool.py
new file mode 100644
index 0000000..12e4f39
--- /dev/null
+++ b/tests/pool/fix_pool.py
@@ -0,0 +1,12 @@
+import pytest
+
+
+def pytest_configure(config):
+    config.addinivalue_line("markers", "pool: test related to the psycopg_pool package")
+
+
+def pytest_collection_modifyitems(items):
+    # Add the pool markers to all the tests in the pool package
+    for item in items:
+        if "/pool/" in item.nodeid:
+            item.add_marker(pytest.mark.pool)
diff --git a/tests/pool/test_null_pool.py b/tests/pool/test_null_pool.py
new file mode 100644
index 0000000..c0e8060
--- /dev/null
+++ b/tests/pool/test_null_pool.py
@@ -0,0 +1,896 @@
+import logging
+from time import sleep, time
+from threading import Thread, Event
+from typing import Any, List, Tuple
+
+import pytest
+from packaging.version import parse as ver  # noqa: F401  # used in skipif
+
+import psycopg
+from psycopg.pq import TransactionStatus
+
+from .test_pool import delay_connection, ensure_waiting
+
+try:
+    from psycopg_pool import NullConnectionPool
+    from psycopg_pool import PoolClosed, PoolTimeout, TooManyRequests
+except ImportError:
+    pass
+
+
+def test_defaults(dsn):
+    with NullConnectionPool(dsn) as p:
+        assert p.min_size == p.max_size == 0
+        assert p.timeout == 30
+        assert p.max_idle == 10 * 60
+        assert p.max_lifetime == 60 * 60
+        assert p.num_workers == 3
+
+
+def test_min_size_max_size(dsn):
+    with NullConnectionPool(dsn, min_size=0, max_size=2) as p:
+        assert p.min_size == 0
+        assert p.max_size == 2
+
+
+@pytest.mark.parametrize("min_size, max_size", [(1, None), (-1, None), (0, -2)])
+def test_bad_size(dsn, min_size, max_size):
+    with pytest.raises(ValueError):
+        NullConnectionPool(min_size=min_size, max_size=max_size)
+
+
+def test_connection_class(dsn):
+    class MyConn(psycopg.Connection[Any]):
+        pass
+
+    with NullConnectionPool(dsn, connection_class=MyConn) as p:
+        with p.connection() as conn:
+            assert isinstance(conn, MyConn)
+
+
+def test_kwargs(dsn):
+    with NullConnectionPool(dsn, kwargs={"autocommit": True}) as p:
+        with p.connection() as conn:
+            assert conn.autocommit
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_its_no_pool_at_all(dsn):
+    with NullConnectionPool(dsn, max_size=2) as p:
+        with p.connection() as conn:
+            pid1 = conn.info.backend_pid
+
+            with p.connection() as conn2:
+                pid2 = conn2.info.backend_pid
+
+        with p.connection() as conn:
+            assert conn.info.backend_pid not in (pid1, pid2)
+
+
+def test_context(dsn):
+    with NullConnectionPool(dsn) as p:
+        assert not p.closed
+    assert p.closed
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+def test_wait_ready(dsn, monkeypatch):
+    delay_connection(monkeypatch, 0.2)
+    with pytest.raises(PoolTimeout):
+        with NullConnectionPool(dsn, num_workers=1) as p:
+            p.wait(0.1)
+
+    with NullConnectionPool(dsn, num_workers=1) as p:
+        p.wait(0.4)
+
+
+def test_wait_closed(dsn):
+    with NullConnectionPool(dsn) as p:
+        pass
+
+    with pytest.raises(PoolClosed):
+        p.wait()
+
+
+@pytest.mark.slow
+def test_setup_no_timeout(dsn, proxy):
+    with pytest.raises(PoolTimeout):
+        with NullConnectionPool(proxy.client_dsn, num_workers=1) as p:
+            p.wait(0.2)
+
+    with NullConnectionPool(proxy.client_dsn, num_workers=1) as p:
+        sleep(0.5)
+        assert not p._pool
+        proxy.start()
+
+        with p.connection() as conn:
+            conn.execute("select 1")
+
+
+def test_configure(dsn):
+    inits = 0
+
+    def configure(conn):
+        nonlocal inits
+        inits += 1
+        with conn.transaction():
+            conn.execute("set default_transaction_read_only to on")
+
+    with NullConnectionPool(dsn, configure=configure) as p:
+        with p.connection() as conn:
+            assert inits == 1
+            res = conn.execute("show default_transaction_read_only")
+            assert res.fetchone()[0] == "on"  # type: ignore[index]
+
+        with p.connection() as conn:
+            assert inits == 2
+            res = conn.execute("show default_transaction_read_only")
+            assert res.fetchone()[0] == "on"  # type: ignore[index]
+            conn.close()
+
+        with p.connection() as conn:
+            assert inits == 3
+            res = conn.execute("show default_transaction_read_only")
+            assert res.fetchone()[0] == "on"  # type: ignore[index]
+
+
+@pytest.mark.slow
+def test_configure_badstate(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    def configure(conn):
+        conn.execute("select 1")
+
+    with NullConnectionPool(dsn, configure=configure) as p:
+        with pytest.raises(PoolTimeout):
+            p.wait(timeout=0.5)
+
+    assert caplog.records
+    assert "INTRANS" in caplog.records[0].message
+
+
+@pytest.mark.slow
+def test_configure_broken(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    def configure(conn):
+        with conn.transaction():
+            conn.execute("WAT")
+
+    with NullConnectionPool(dsn, configure=configure) as p:
+        with pytest.raises(PoolTimeout):
+            p.wait(timeout=0.5)
+
+    assert caplog.records
+    assert "WAT" in caplog.records[0].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_reset(dsn):
+    resets = 0
+
+    def setup(conn):
+        with conn.transaction():
+            conn.execute("set timezone to '+1:00'")
+
+    def reset(conn):
+        nonlocal resets
+        resets += 1
+        with conn.transaction():
+            conn.execute("set timezone to utc")
+
+    pids = []
+
+    def worker():
+        with p.connection() as conn:
+            assert resets == 1
+            with conn.execute("show timezone") as cur:
+                assert cur.fetchone() == ("UTC",)
+            pids.append(conn.info.backend_pid)
+
+    with NullConnectionPool(dsn, max_size=1, reset=reset) as p:
+        with p.connection() as conn:
+
+            # Queue the worker so it will take the same connection a second time
+            # instead of making a new one.
+            t = Thread(target=worker)
+            t.start()
+            ensure_waiting(p)
+
+            assert resets == 0
+            conn.execute("set timezone to '+2:00'")
+            pids.append(conn.info.backend_pid)
+
+        t.join()
+        p.wait()
+
+    assert resets == 1
+    assert pids[0] == pids[1]
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_reset_badstate(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    def reset(conn):
+        conn.execute("reset all")
+
+    pids = []
+
+    def worker():
+        with p.connection() as conn:
+            conn.execute("select 1")
+            pids.append(conn.info.backend_pid)
+
+    with NullConnectionPool(dsn, max_size=1, reset=reset) as p:
+        with p.connection() as conn:
+
+            t = Thread(target=worker)
+            t.start()
+            ensure_waiting(p)
+
+            conn.execute("select 1")
+            pids.append(conn.info.backend_pid)
+
+        t.join()
+
+    assert pids[0] != pids[1]
+    assert caplog.records
+    assert "INTRANS" in caplog.records[0].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_reset_broken(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    def reset(conn):
+        with conn.transaction():
+            conn.execute("WAT")
+
+    pids = []
+
+    def worker():
+        with p.connection() as conn:
+            conn.execute("select 1")
+            pids.append(conn.info.backend_pid)
+
+    with NullConnectionPool(dsn, max_size=1, reset=reset) as p:
+        with p.connection() as conn:
+
+            t = Thread(target=worker)
+            t.start()
+            ensure_waiting(p)
+
+            conn.execute("select 1")
+            pids.append(conn.info.backend_pid)
+
+        t.join()
+
+    assert pids[0] != pids[1]
+    assert caplog.records
+    assert "WAT" in caplog.records[0].message
+
+
+@pytest.mark.slow
+@pytest.mark.skipif("ver(psycopg.__version__) < ver('3.0.8')")
+def test_no_queue_timeout(deaf_port):
+    with NullConnectionPool(kwargs={"host": "localhost", "port": deaf_port}) as p:
+        with pytest.raises(PoolTimeout):
+            with p.connection(timeout=1):
+                pass
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.crdb_skip("backend pid")
+def test_queue(dsn):
+    def worker(n):
+        t0 = time()
+        with p.connection() as conn:
+            conn.execute("select pg_sleep(0.2)")
+            pid = conn.info.backend_pid
+
+        t1 = time()
+        results.append((n, t1 - t0, pid))
+
+    results: List[Tuple[int, float, int]] = []
+    with NullConnectionPool(dsn, max_size=2) as p:
+        p.wait()
+        ts = [Thread(target=worker, args=(i,)) for i in range(6)]
+        for t in ts:
+            t.start()
+        for t in ts:
+            t.join()
+
+    times = [item[1] for item in results]
+    want_times = [0.2, 0.2, 0.4, 0.4, 0.6, 0.6]
+    for got, want in zip(times, want_times):
+        assert got == pytest.approx(want, 0.2), times
+
+    assert len(set(r[2] for r in results)) == 2, results
+
+
+@pytest.mark.slow
+def test_queue_size(dsn):
+    def worker(t, ev=None):
+        try:
+            with p.connection():
+                if ev:
+                    ev.set()
+                sleep(t)
+        except TooManyRequests as e:
+            errors.append(e)
+        else:
+            success.append(True)
+
+    errors: List[Exception] = []
+    success: List[bool] = []
+
+    with NullConnectionPool(dsn, max_size=1, max_waiting=3) as p:
+        p.wait()
+        ev = Event()
+        t = Thread(target=worker, args=(0.3, ev))
+        t.start()
+        ev.wait()
+
+        ts = [Thread(target=worker, args=(0.1,)) for i in range(4)]
+        for t in ts:
+            t.start()
+        for t in ts:
+            t.join()
+
+    assert len(success) == 4
+    assert len(errors) == 1
+    assert isinstance(errors[0], TooManyRequests)
+    assert p.name in str(errors[0])
+    assert str(p.max_waiting) in str(errors[0])
+    assert p.get_stats()["requests_errors"] == 1
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.crdb_skip("backend pid")
+def test_queue_timeout(dsn):
+    def worker(n):
+        t0 = time()
+        try:
+            with p.connection() as conn:
+                conn.execute("select pg_sleep(0.2)")
+                pid = conn.info.backend_pid
+        except PoolTimeout as e:
+            t1 = time()
+            errors.append((n, t1 - t0, e))
+        else:
+            t1 = time()
+            results.append((n, t1 - t0, pid))
+
+    results: List[Tuple[int, float, int]] = []
+    errors: List[Tuple[int, float, Exception]] = []
+
+    with NullConnectionPool(dsn, max_size=2, timeout=0.1) as p:
+        ts = [Thread(target=worker, args=(i,)) for i in range(4)]
+        for t in ts:
+            t.start()
+        for t in ts:
+            t.join()
+
+    assert len(results) == 2
+    assert len(errors) == 2
+    for e in errors:
+        assert 0.1 < e[1] < 0.15
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+def test_dead_client(dsn):
+    def worker(i, timeout):
+        try:
+            with p.connection(timeout=timeout) as conn:
+                conn.execute("select pg_sleep(0.3)")
+                results.append(i)
+        except PoolTimeout:
+            if timeout > 0.2:
+                raise
+
+    results: List[int] = []
+
+    with NullConnectionPool(dsn, max_size=2) as p:
+        ts = [
+            Thread(target=worker, args=(i, timeout))
+            for i, timeout in enumerate([0.4, 0.4, 0.1, 0.4, 0.4])
+        ]
+        for t in ts:
+            t.start()
+        for t in ts:
+            t.join()
+        sleep(0.2)
+        assert set(results) == set([0, 1, 3, 4])
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.crdb_skip("backend pid")
+def test_queue_timeout_override(dsn):
+    def worker(n):
+        t0 = time()
+        timeout = 0.25 if n == 3 else None
+        try:
+            with p.connection(timeout=timeout) as conn:
+                conn.execute("select pg_sleep(0.2)")
+                pid = conn.info.backend_pid
+        except PoolTimeout as e:
+            t1 = time()
+            errors.append((n, t1 - t0, e))
+        else:
+            t1 = time()
+            results.append((n, t1 - t0, pid))
+
+    results: List[Tuple[int, float, int]] = []
+    errors: List[Tuple[int, float, Exception]] = []
+
+    with NullConnectionPool(dsn, max_size=2, timeout=0.1) as p:
+        ts = [Thread(target=worker, args=(i,)) for i in range(4)]
+        for t in ts:
+            t.start()
+        for t in ts:
+            t.join()
+
+    assert len(results) == 3
+    assert len(errors) == 1
+    for e in errors:
+        assert 0.1 < e[1] < 0.15
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_broken_reconnect(dsn):
+    with NullConnectionPool(dsn, max_size=1) as p:
+        with p.connection() as conn:
+            pid1 = conn.info.backend_pid
+            conn.close()
+
+        with p.connection() as conn2:
+            pid2 = conn2.info.backend_pid
+
+    assert pid1 != pid2
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_intrans_rollback(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+    pids = []
+
+    def worker():
+        with p.connection() as conn:
+            pids.append(conn.info.backend_pid)
+            assert conn.info.transaction_status == TransactionStatus.IDLE
+            assert not conn.execute(
+                "select 1 from pg_class where relname = 'test_intrans_rollback'"
+            ).fetchone()
+
+    with NullConnectionPool(dsn, max_size=1) as p:
+        conn = p.getconn()
+
+        # Queue the worker so it will take the connection a second time instead
+        # of making a new one.
+        t = Thread(target=worker)
+        t.start()
+        ensure_waiting(p)
+
+        pids.append(conn.info.backend_pid)
+        conn.execute("create table test_intrans_rollback ()")
+        assert conn.info.transaction_status == TransactionStatus.INTRANS
+        p.putconn(conn)
+        t.join()
+
+    assert pids[0] == pids[1]
+    assert len(caplog.records) == 1
+    assert "INTRANS" in caplog.records[0].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_inerror_rollback(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+    pids = []
+
+    def worker():
+        with p.connection() as conn:
+            pids.append(conn.info.backend_pid)
+            assert conn.info.transaction_status == TransactionStatus.IDLE
+
+    with NullConnectionPool(dsn, max_size=1) as p:
+        conn = p.getconn()
+
+        # Queue the worker so it will take the connection a second time instead
+        # of making a new one.
+        t = Thread(target=worker)
+        t.start()
+        ensure_waiting(p)
+
+        pids.append(conn.info.backend_pid)
+        with pytest.raises(psycopg.ProgrammingError):
+            conn.execute("wat")
+        assert conn.info.transaction_status == TransactionStatus.INERROR
+        p.putconn(conn)
+        t.join()
+
+    assert pids[0] == pids[1]
+    assert len(caplog.records) == 1
+    assert "INERROR" in caplog.records[0].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+@pytest.mark.crdb_skip("copy")
+def test_active_close(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+    pids = []
+
+    def worker():
+        with p.connection() as conn:
+            pids.append(conn.info.backend_pid)
+            assert conn.info.transaction_status == TransactionStatus.IDLE
+
+    with NullConnectionPool(dsn, max_size=1) as p:
+        conn = p.getconn()
+
+        t = Thread(target=worker)
+        t.start()
+        ensure_waiting(p)
+
+        pids.append(conn.info.backend_pid)
+        conn.pgconn.exec_(b"copy (select * from generate_series(1, 10)) to stdout")
+        assert conn.info.transaction_status == TransactionStatus.ACTIVE
+        p.putconn(conn)
+        t.join()
+
+    assert pids[0] != pids[1]
+    assert len(caplog.records) == 2
+    assert "ACTIVE" in caplog.records[0].message
+    assert "BAD" in caplog.records[1].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_fail_rollback_close(dsn, caplog, monkeypatch):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+    pids = []
+
+    def worker(p):
+        with p.connection() as conn:
+            pids.append(conn.info.backend_pid)
+            assert conn.info.transaction_status == TransactionStatus.IDLE
+
+    with NullConnectionPool(dsn, max_size=1) as p:
+        conn = p.getconn()
+
+        def bad_rollback():
+            conn.pgconn.finish()
+            orig_rollback()
+
+        # Make the rollback fail
+        orig_rollback = conn.rollback
+        monkeypatch.setattr(conn, "rollback", bad_rollback)
+
+        t = Thread(target=worker, args=(p,))
+        t.start()
+        ensure_waiting(p)
+
+        pids.append(conn.info.backend_pid)
+        with pytest.raises(psycopg.ProgrammingError):
+            conn.execute("wat")
+        assert conn.info.transaction_status == TransactionStatus.INERROR
+        p.putconn(conn)
+        t.join()
+
+    assert pids[0] != pids[1]
+    assert len(caplog.records) == 3
+    assert "INERROR" in caplog.records[0].message
+    assert "OperationalError" in caplog.records[1].message
+    assert "BAD" in caplog.records[2].message
+
+
+def test_close_no_threads(dsn):
+    p = NullConnectionPool(dsn)
+    assert p._sched_runner and p._sched_runner.is_alive()
+    workers = p._workers[:]
+    assert workers
+    for t in workers:
+        assert t.is_alive()
+
+    p.close()
+    assert p._sched_runner is None
+    assert not p._workers
+    for t in workers:
+        assert not t.is_alive()
+
+
+def test_putconn_no_pool(conn_cls, dsn):
+    with NullConnectionPool(dsn) as p:
+        conn = conn_cls.connect(dsn)
+        with pytest.raises(ValueError):
+            p.putconn(conn)
+
+    conn.close()
+
+
+def test_putconn_wrong_pool(dsn):
+    with NullConnectionPool(dsn) as p1:
+        with NullConnectionPool(dsn) as p2:
+            conn = p1.getconn()
+            with pytest.raises(ValueError):
+                p2.putconn(conn)
+
+
+@pytest.mark.slow
+def test_del_stop_threads(dsn):
+    p = NullConnectionPool(dsn)
+    assert p._sched_runner is not None
+    ts = [p._sched_runner] + p._workers
+    del p
+    sleep(0.1)
+    for t in ts:
+        assert not t.is_alive()
+
+
+def test_closed_getconn(dsn):
+    p = NullConnectionPool(dsn)
+    assert not p.closed
+    with p.connection():
+        pass
+
+    p.close()
+    assert p.closed
+
+    with pytest.raises(PoolClosed):
+        with p.connection():
+            pass
+
+
+def test_closed_putconn(dsn):
+    p = NullConnectionPool(dsn)
+
+    with p.connection() as conn:
+        pass
+    assert conn.closed
+
+    with p.connection() as conn:
+        p.close()
+    assert conn.closed
+
+
+def test_closed_queue(dsn):
+    def w1():
+        with p.connection() as conn:
+            e1.set()  # Tell w0 that w1 got a connection
+            cur = conn.execute("select 1")
+            assert cur.fetchone() == (1,)
+            e2.wait()  # Wait until w0 has tested w2
+        success.append("w1")
+
+    def w2():
+        try:
+            with p.connection():
+                pass  # unexpected
+        except PoolClosed:
+            success.append("w2")
+
+    e1 = Event()
+    e2 = Event()
+
+    p = NullConnectionPool(dsn, max_size=1)
+    p.wait()
+    success: List[str] = []
+
+    t1 = Thread(target=w1)
+    t1.start()
+    # Wait until w1 has received a connection
+    e1.wait()
+
+    t2 = Thread(target=w2)
+    t2.start()
+    # Wait until w2 is in the queue
+    ensure_waiting(p)
+
+    p.close(0)
+
+    # Wait for the workers to finish
+    e2.set()
+    t1.join()
+    t2.join()
+    assert len(success) == 2
+
+
+def test_open_explicit(dsn):
+    p = NullConnectionPool(dsn, open=False)
+    assert p.closed
+    with pytest.raises(PoolClosed, match="is not open yet"):
+        p.getconn()
+
+    with pytest.raises(PoolClosed):
+        with p.connection():
+            pass
+
+    p.open()
+    try:
+        assert not p.closed
+
+        with p.connection() as conn:
+            cur = conn.execute("select 1")
+            assert cur.fetchone() == (1,)
+
+    finally:
+        p.close()
+
+    with pytest.raises(PoolClosed, match="is already closed"):
+        p.getconn()
+
+
+def test_open_context(dsn):
+    p = NullConnectionPool(dsn, open=False)
+    assert p.closed
+
+    with p:
+        assert not p.closed
+
+        with p.connection() as conn:
+            cur = conn.execute("select 1")
+            assert cur.fetchone() == (1,)
+
+    assert p.closed
+
+
+def test_open_no_op(dsn):
+    p = NullConnectionPool(dsn)
+    try:
+        assert not p.closed
+        p.open()
+        assert not p.closed
+
+        with p.connection() as conn:
+            cur = conn.execute("select 1")
+            assert cur.fetchone() == (1,)
+
+    finally:
+        p.close()
+
+
+def test_reopen(dsn):
+    p = NullConnectionPool(dsn)
+    with p.connection() as conn:
+        conn.execute("select 1")
+    p.close()
+    assert p._sched_runner is None
+    assert not p._workers
+
+    with pytest.raises(psycopg.OperationalError, match="cannot be reused"):
+        p.open()
+
+
+@pytest.mark.parametrize("min_size, max_size", [(1, None), (-1, None), (0, -2)])
+def test_bad_resize(dsn, min_size, max_size):
+    with NullConnectionPool() as p:
+        with pytest.raises(ValueError):
+            p.resize(min_size=min_size, max_size=max_size)
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.crdb_skip("backend pid")
+def test_max_lifetime(dsn):
+    pids = []
+
+    def worker(p):
+        with p.connection() as conn:
+            pids.append(conn.info.backend_pid)
+            sleep(0.1)
+
+    ts = []
+    with NullConnectionPool(dsn, max_size=1, max_lifetime=0.2) as p:
+        for i in range(5):
+            ts.append(Thread(target=worker, args=(p,)))
+            ts[-1].start()
+
+        for t in ts:
+            t.join()
+
+    assert pids[0] == pids[1] != pids[4], pids
+
+
+def test_check(dsn):
+    with NullConnectionPool(dsn) as p:
+        # No-op
+        p.check()
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+def test_stats_measures(dsn):
+    def worker(n):
+        with p.connection() as conn:
+            conn.execute("select pg_sleep(0.2)")
+
+    with NullConnectionPool(dsn, max_size=4) as p:
+        p.wait(2.0)
+
+        stats = p.get_stats()
+        assert stats["pool_min"] == 0
+        assert stats["pool_max"] == 4
+        assert stats["pool_size"] == 0
+        assert stats["pool_available"] == 0
+        assert stats["requests_waiting"] == 0
+
+        ts = [Thread(target=worker, args=(i,)) for i in range(3)]
+        for t in ts:
+            t.start()
+        sleep(0.1)
+        stats = p.get_stats()
+        for t in ts:
+            t.join()
+        assert stats["pool_min"] == 0
+        assert stats["pool_max"] == 4
+        assert stats["pool_size"] == 3
+        assert stats["pool_available"] == 0
+        assert stats["requests_waiting"] == 0
+
+        p.wait(2.0)
+        ts = [Thread(target=worker, args=(i,)) for i in range(7)]
+        for t in ts:
+            t.start()
+        sleep(0.1)
+        stats = p.get_stats()
+        for t in ts:
+            t.join()
+        assert stats["pool_min"] == 0
+        assert stats["pool_max"] == 4
+        assert stats["pool_size"] == 4
+        assert stats["pool_available"] == 0
+        assert stats["requests_waiting"] == 3
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+def test_stats_usage(dsn):
+    def worker(n):
+        try:
+            with p.connection(timeout=0.3) as conn:
+                conn.execute("select pg_sleep(0.2)")
+        except PoolTimeout:
+            pass
+
+    with NullConnectionPool(dsn, max_size=3) as p:
+        p.wait(2.0)
+
+        ts = [Thread(target=worker, args=(i,)) for i in range(7)]
+        for t in ts:
+            t.start()
+        for t in ts:
+            t.join()
+        stats = p.get_stats()
+        assert stats["requests_num"] == 7
+        assert stats["requests_queued"] == 4
+        assert 850 <= stats["requests_wait_ms"] <= 950
+        assert stats["requests_errors"] == 1
+        assert 1150 <= stats["usage_ms"] <= 1250
+        assert stats.get("returns_bad", 0) == 0
+
+        with p.connection() as conn:
+            conn.close()
+        p.wait()
+        stats = p.pop_stats()
+        assert stats["requests_num"] == 8
+        assert stats["returns_bad"] == 1
+        with p.connection():
+            pass
+        assert p.get_stats()["requests_num"] == 1
+
+
+@pytest.mark.slow
+def test_stats_connect(dsn, proxy, monkeypatch):
+    proxy.start()
+    delay_connection(monkeypatch, 0.2)
+    with NullConnectionPool(proxy.client_dsn, max_size=3) as p:
+        p.wait()
+        stats = p.get_stats()
+        assert stats["connections_num"] == 1
+        assert stats.get("connections_errors", 0) == 0
+        assert stats.get("connections_lost", 0) == 0
+        assert 200 <= stats["connections_ms"] < 300
diff --git a/tests/pool/test_null_pool_async.py b/tests/pool/test_null_pool_async.py
new file mode 100644
index 0000000..23a1a52
--- /dev/null
+++ b/tests/pool/test_null_pool_async.py
@@ -0,0 +1,844 @@
+import asyncio
+import logging
+from time import time
+from typing import Any, List, Tuple
+
+import pytest
+from packaging.version import parse as ver  # noqa: F401  # used in skipif
+
+import psycopg
+from psycopg.pq import TransactionStatus
+from psycopg._compat import create_task
+from .test_pool_async import delay_connection, ensure_waiting
+
+pytestmark = [pytest.mark.asyncio]
+
+try:
+    from psycopg_pool import AsyncNullConnectionPool  # noqa: F401
+    from psycopg_pool import PoolClosed, PoolTimeout, TooManyRequests
+except ImportError:
+    pass
+
+
+async def test_defaults(dsn):
+    async with AsyncNullConnectionPool(dsn) as p:
+        assert p.min_size == p.max_size == 0
+        assert p.timeout == 30
+        assert p.max_idle == 10 * 60
+        assert p.max_lifetime == 60 * 60
+        assert p.num_workers == 3
+
+
+async def test_min_size_max_size(dsn):
+    async with AsyncNullConnectionPool(dsn, min_size=0, max_size=2) as p:
+        assert p.min_size == 0
+        assert p.max_size == 2
+
+
+@pytest.mark.parametrize("min_size, max_size", [(1, None), (-1, None), (0, -2)])
+async def test_bad_size(dsn, min_size, max_size):
+    with pytest.raises(ValueError):
+        AsyncNullConnectionPool(min_size=min_size, max_size=max_size)
+
+
+async def test_connection_class(dsn):
+    class MyConn(psycopg.AsyncConnection[Any]):
+        pass
+
+    async with AsyncNullConnectionPool(dsn, connection_class=MyConn) as p:
+        async with p.connection() as conn:
+            assert isinstance(conn, MyConn)
+
+
+async def test_kwargs(dsn):
+    async with AsyncNullConnectionPool(dsn, kwargs={"autocommit": True}) as p:
+        async with p.connection() as conn:
+            assert conn.autocommit
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_its_no_pool_at_all(dsn):
+    async with AsyncNullConnectionPool(dsn, max_size=2) as p:
+        async with p.connection() as conn:
+            pid1 = conn.info.backend_pid
+
+            async with p.connection() as conn2:
+                pid2 = conn2.info.backend_pid
+
+        async with p.connection() as conn:
+            assert conn.info.backend_pid not in (pid1, pid2)
+
+
+async def test_context(dsn):
+    async with AsyncNullConnectionPool(dsn) as p:
+        assert not p.closed
+    assert p.closed
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+async def test_wait_ready(dsn, monkeypatch):
+    delay_connection(monkeypatch, 0.2)
+    with pytest.raises(PoolTimeout):
+        async with AsyncNullConnectionPool(dsn, num_workers=1) as p:
+            await p.wait(0.1)
+
+    async with AsyncNullConnectionPool(dsn, num_workers=1) as p:
+        await p.wait(0.4)
+
+
+async def test_wait_closed(dsn):
+    async with AsyncNullConnectionPool(dsn) as p:
+        pass
+
+    with pytest.raises(PoolClosed):
+        await p.wait()
+
+
+@pytest.mark.slow
+async def test_setup_no_timeout(dsn, proxy):
+    with pytest.raises(PoolTimeout):
+        async with AsyncNullConnectionPool(proxy.client_dsn, num_workers=1) as p:
+            await p.wait(0.2)
+
+    async with AsyncNullConnectionPool(proxy.client_dsn, num_workers=1) as p:
+        await asyncio.sleep(0.5)
+        assert not p._pool
+        proxy.start()
+
+        async with p.connection() as conn:
+            await conn.execute("select 1")
+
+
+async def test_configure(dsn):
+    inits = 0
+
+    async def configure(conn):
+        nonlocal inits
+        inits += 1
+        async with conn.transaction():
+            await conn.execute("set default_transaction_read_only to on")
+
+    async with AsyncNullConnectionPool(dsn, configure=configure) as p:
+        async with p.connection() as conn:
+            assert inits == 1
+            res = await conn.execute("show default_transaction_read_only")
+            assert (await res.fetchone())[0] == "on"  # type: ignore[index]
+
+        async with p.connection() as conn:
+            assert inits == 2
+            res = await conn.execute("show default_transaction_read_only")
+            assert (await res.fetchone())[0] == "on"  # type: ignore[index]
+            await conn.close()
+
+        async with p.connection() as conn:
+            assert inits == 3
+            res = await conn.execute("show default_transaction_read_only")
+            assert (await res.fetchone())[0] == "on"  # type: ignore[index]
+
+
+@pytest.mark.slow
+async def test_configure_badstate(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    async def configure(conn):
+        await conn.execute("select 1")
+
+    async with AsyncNullConnectionPool(dsn, configure=configure) as p:
+        with pytest.raises(PoolTimeout):
+            await p.wait(timeout=0.5)
+
+    assert caplog.records
+    assert "INTRANS" in caplog.records[0].message
+
+
+@pytest.mark.slow
+async def test_configure_broken(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    async def configure(conn):
+        async with conn.transaction():
+            await conn.execute("WAT")
+
+    async with AsyncNullConnectionPool(dsn, configure=configure) as p:
+        with pytest.raises(PoolTimeout):
+            await p.wait(timeout=0.5)
+
+    assert caplog.records
+    assert "WAT" in caplog.records[0].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_reset(dsn):
+    resets = 0
+
+    async def setup(conn):
+        async with conn.transaction():
+            await conn.execute("set timezone to '+1:00'")
+
+    async def reset(conn):
+        nonlocal resets
+        resets += 1
+        async with conn.transaction():
+            await conn.execute("set timezone to utc")
+
+    pids = []
+
+    async def worker():
+        async with p.connection() as conn:
+            assert resets == 1
+            cur = await conn.execute("show timezone")
+            assert (await cur.fetchone()) == ("UTC",)
+            pids.append(conn.info.backend_pid)
+
+    async with AsyncNullConnectionPool(dsn, max_size=1, reset=reset) as p:
+        async with p.connection() as conn:
+
+            # Queue the worker so it will take the same connection a second time
+            # instead of making a new one.
+            t = create_task(worker())
+            await ensure_waiting(p)
+
+            assert resets == 0
+            await conn.execute("set timezone to '+2:00'")
+            pids.append(conn.info.backend_pid)
+
+        await asyncio.gather(t)
+        await p.wait()
+
+    assert resets == 1
+    assert pids[0] == pids[1]
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_reset_badstate(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    async def reset(conn):
+        await conn.execute("reset all")
+
+    pids = []
+
+    async def worker():
+        async with p.connection() as conn:
+            await conn.execute("select 1")
+            pids.append(conn.info.backend_pid)
+
+    async with AsyncNullConnectionPool(dsn, max_size=1, reset=reset) as p:
+        async with p.connection() as conn:
+
+            t = create_task(worker())
+            await ensure_waiting(p)
+
+            await conn.execute("select 1")
+            pids.append(conn.info.backend_pid)
+
+        await asyncio.gather(t)
+
+    assert pids[0] != pids[1]
+    assert caplog.records
+    assert "INTRANS" in caplog.records[0].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_reset_broken(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    async def reset(conn):
+        async with conn.transaction():
+            await conn.execute("WAT")
+
+    pids = []
+
+    async def worker():
+        async with p.connection() as conn:
+            await conn.execute("select 1")
+            pids.append(conn.info.backend_pid)
+
+    async with AsyncNullConnectionPool(dsn, max_size=1, reset=reset) as p:
+        async with p.connection() as conn:
+
+            t = create_task(worker())
+            await ensure_waiting(p)
+
+            await conn.execute("select 1")
+            pids.append(conn.info.backend_pid)
+
+        await asyncio.gather(t)
+
+    assert pids[0] != pids[1]
+    assert caplog.records
+    assert "WAT" in caplog.records[0].message
+
+
+@pytest.mark.slow
+@pytest.mark.skipif("ver(psycopg.__version__) < ver('3.0.8')")
+async def test_no_queue_timeout(deaf_port):
+    async with AsyncNullConnectionPool(
+        kwargs={"host": "localhost", "port": deaf_port}
+    ) as p:
+        with pytest.raises(PoolTimeout):
+            async with p.connection(timeout=1):
+                pass
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.crdb_skip("backend pid")
+async def test_queue(dsn):
+    async def worker(n):
+        t0 = time()
+        async with p.connection() as conn:
+            await conn.execute("select pg_sleep(0.2)")
+            pid = conn.info.backend_pid
+        t1 = time()
+        results.append((n, t1 - t0, pid))
+
+    results: List[Tuple[int, float, int]] = []
+    async with AsyncNullConnectionPool(dsn, max_size=2) as p:
+        await p.wait()
+        ts = [create_task(worker(i)) for i in range(6)]
+        await asyncio.gather(*ts)
+
+    times = [item[1] for item in results]
+    want_times = [0.2, 0.2, 0.4, 0.4, 0.6, 0.6]
+    for got, want in zip(times, want_times):
+        assert got == pytest.approx(want, 0.2), times
+
+    assert len(set(r[2] for r in results)) == 2, results
+
+
+@pytest.mark.slow
+async def test_queue_size(dsn):
+    async def worker(t, ev=None):
+        try:
+            async with p.connection():
+                if ev:
+                    ev.set()
+                await asyncio.sleep(t)
+        except TooManyRequests as e:
+            errors.append(e)
+        else:
+            success.append(True)
+
+    errors: List[Exception] = []
+    success: List[bool] = []
+
+    async with AsyncNullConnectionPool(dsn, max_size=1, max_waiting=3) as p:
+        await p.wait()
+        ev = asyncio.Event()
+        create_task(worker(0.3, ev))
+        await ev.wait()
+
+        ts = [create_task(worker(0.1)) for i in range(4)]
+        await asyncio.gather(*ts)
+
+    assert len(success) == 4
+    assert len(errors) == 1
+    assert isinstance(errors[0], TooManyRequests)
+    assert p.name in str(errors[0])
+    assert str(p.max_waiting) in str(errors[0])
+    assert p.get_stats()["requests_errors"] == 1
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.crdb_skip("backend pid")
+async def test_queue_timeout(dsn):
+    async def worker(n):
+        t0 = time()
+        try:
+            async with p.connection() as conn:
+                await conn.execute("select pg_sleep(0.2)")
+                pid = conn.info.backend_pid
+        except PoolTimeout as e:
+            t1 = time()
+            errors.append((n, t1 - t0, e))
+        else:
+            t1 = time()
+            results.append((n, t1 - t0, pid))
+
+    results: List[Tuple[int, float, int]] = []
+    errors: List[Tuple[int, float, Exception]] = []
+
+    async with AsyncNullConnectionPool(dsn, max_size=2, timeout=0.1) as p:
+        ts = [create_task(worker(i)) for i in range(4)]
+        await asyncio.gather(*ts)
+
+    assert len(results) == 2
+    assert len(errors) == 2
+    for e in errors:
+        assert 0.1 < e[1] < 0.15
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+async def test_dead_client(dsn):
+    async def worker(i, timeout):
+        try:
+            async with p.connection(timeout=timeout) as conn:
+                await conn.execute("select pg_sleep(0.3)")
+                results.append(i)
+        except PoolTimeout:
+            if timeout > 0.2:
+                raise
+
+    async with AsyncNullConnectionPool(dsn, max_size=2) as p:
+        results: List[int] = []
+        ts = [
+            create_task(worker(i, timeout))
+            for i, timeout in enumerate([0.4, 0.4, 0.1, 0.4, 0.4])
+        ]
+        await asyncio.gather(*ts)
+
+        await asyncio.sleep(0.2)
+        assert set(results) == set([0, 1, 3, 4])
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.crdb_skip("backend pid")
+async def test_queue_timeout_override(dsn):
+    async def worker(n):
+        t0 = time()
+        timeout = 0.25 if n == 3 else None
+        try:
+            async with p.connection(timeout=timeout) as conn:
+                await conn.execute("select pg_sleep(0.2)")
+                pid = conn.info.backend_pid
+        except PoolTimeout as e:
+            t1 = time()
+            errors.append((n, t1 - t0, e))
+        else:
+            t1 = time()
+            results.append((n, t1 - t0, pid))
+
+    results: List[Tuple[int, float, int]] = []
+    errors: List[Tuple[int, float, Exception]] = []
+
+    async with AsyncNullConnectionPool(dsn, max_size=2, timeout=0.1) as p:
+        ts = [create_task(worker(i)) for i in range(4)]
+        await asyncio.gather(*ts)
+
+    assert len(results) == 3
+    assert len(errors) == 1
+    for e in errors:
+        assert 0.1 < e[1] < 0.15
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_broken_reconnect(dsn):
+    async with AsyncNullConnectionPool(dsn, max_size=1) as p:
+        async with p.connection() as conn:
+            pid1 = conn.info.backend_pid
+            await conn.close()
+
+        async with p.connection() as conn2:
+            pid2 = conn2.info.backend_pid
+
+    assert pid1 != pid2
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_intrans_rollback(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+    pids = []
+
+    async def worker():
+        async with p.connection() as conn:
+            pids.append(conn.info.backend_pid)
+            assert conn.info.transaction_status == TransactionStatus.IDLE
+            cur = await conn.execute(
+                "select 1 from pg_class where relname = 'test_intrans_rollback'"
+            )
+            assert not await cur.fetchone()
+
+    async with AsyncNullConnectionPool(dsn, max_size=1) as p:
+        conn = await p.getconn()
+
+        # Queue the worker so it will take the connection a second time instead
+        # of making a new one.
+        t = create_task(worker())
+        await ensure_waiting(p)
+
+        pids.append(conn.info.backend_pid)
+        await conn.execute("create table test_intrans_rollback ()")
+        assert conn.info.transaction_status == TransactionStatus.INTRANS
+        await p.putconn(conn)
+        await asyncio.gather(t)
+
+    assert pids[0] == pids[1]
+    assert len(caplog.records) == 1
+    assert "INTRANS" in caplog.records[0].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_inerror_rollback(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+    pids = []
+
+    async def worker():
+        async with p.connection() as conn:
+            pids.append(conn.info.backend_pid)
+            assert conn.info.transaction_status == TransactionStatus.IDLE
+
+    async with AsyncNullConnectionPool(dsn, max_size=1) as p:
+        conn = await p.getconn()
+
+        t = create_task(worker())
+        await ensure_waiting(p)
+
+        pids.append(conn.info.backend_pid)
+        with pytest.raises(psycopg.ProgrammingError):
+            await conn.execute("wat")
+        assert conn.info.transaction_status == TransactionStatus.INERROR
+        await p.putconn(conn)
+        await asyncio.gather(t)
+
+    assert pids[0] == pids[1]
+    assert len(caplog.records) == 1
+    assert "INERROR" in caplog.records[0].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+@pytest.mark.crdb_skip("copy")
+async def test_active_close(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+    pids = []
+
+    async def worker():
+        async with p.connection() as conn:
+            pids.append(conn.info.backend_pid)
+            assert conn.info.transaction_status == TransactionStatus.IDLE
+
+    async with AsyncNullConnectionPool(dsn, max_size=1) as p:
+        conn = await p.getconn()
+
+        t = create_task(worker())
+        await ensure_waiting(p)
+
+        pids.append(conn.info.backend_pid)
+        conn.pgconn.exec_(b"copy (select * from generate_series(1, 10)) to stdout")
+        assert conn.info.transaction_status == TransactionStatus.ACTIVE
+        await p.putconn(conn)
+        await asyncio.gather(t)
+
+    assert pids[0] != pids[1]
+    assert len(caplog.records) == 2
+    assert "ACTIVE" in caplog.records[0].message
+    assert "BAD" in caplog.records[1].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_fail_rollback_close(dsn, caplog, monkeypatch):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+    pids = []
+
+    async def worker():
+        async with p.connection() as conn:
+            pids.append(conn.info.backend_pid)
+            assert conn.info.transaction_status == TransactionStatus.IDLE
+
+    async with AsyncNullConnectionPool(dsn, max_size=1) as p:
+        conn = await p.getconn()
+        t = create_task(worker())
+        await ensure_waiting(p)
+
+        async def bad_rollback():
+            conn.pgconn.finish()
+            await orig_rollback()
+
+        # Make the rollback fail
+        orig_rollback = conn.rollback
+        monkeypatch.setattr(conn, "rollback", bad_rollback)
+
+        pids.append(conn.info.backend_pid)
+        with pytest.raises(psycopg.ProgrammingError):
+            await conn.execute("wat")
+        assert conn.info.transaction_status == TransactionStatus.INERROR
+        await p.putconn(conn)
+        await asyncio.gather(t)
+
+    assert pids[0] != pids[1]
+    assert len(caplog.records) == 3
+    assert "INERROR" in caplog.records[0].message
+    assert "OperationalError" in caplog.records[1].message
+    assert "BAD" in caplog.records[2].message
+
+
+async def test_close_no_tasks(dsn):
+    p = AsyncNullConnectionPool(dsn)
+    assert p._sched_runner and not p._sched_runner.done()
+    assert p._workers
+    workers = p._workers[:]
+    for t in workers:
+        assert not t.done()
+
+    await p.close()
+    assert p._sched_runner is None
+    assert not p._workers
+    for t in workers:
+        assert t.done()
+
+
+async def test_putconn_no_pool(aconn_cls, dsn):
+    async with AsyncNullConnectionPool(dsn) as p:
+        conn = await aconn_cls.connect(dsn)
+        with pytest.raises(ValueError):
+            await p.putconn(conn)
+
+    await conn.close()
+
+
+async def test_putconn_wrong_pool(dsn):
+    async with AsyncNullConnectionPool(dsn) as p1:
+        async with AsyncNullConnectionPool(dsn) as p2:
+            conn = await p1.getconn()
+            with pytest.raises(ValueError):
+                await p2.putconn(conn)
+
+
+async def test_closed_getconn(dsn):
+    p = AsyncNullConnectionPool(dsn)
+    assert not p.closed
+    async with p.connection():
+        pass
+
+    await p.close()
+    assert p.closed
+
+    with pytest.raises(PoolClosed):
+        async with p.connection():
+            pass
+
+
+async def test_closed_putconn(dsn):
+    p = AsyncNullConnectionPool(dsn)
+
+    async with p.connection() as conn:
+        pass
+    assert conn.closed
+
+    async with p.connection() as conn:
+        await p.close()
+    assert conn.closed
+
+
+async def test_closed_queue(dsn):
+    async def w1():
+        async with p.connection() as conn:
+            e1.set()  # Tell w0 that w1 got a connection
+            cur = await conn.execute("select 1")
+            assert await cur.fetchone() == (1,)
+            await e2.wait()  # Wait until w0 has tested w2
+        success.append("w1")
+
+    async def w2():
+        try:
+            async with p.connection():
+                pass  # unexpected
+        except PoolClosed:
+            success.append("w2")
+
+    e1 = asyncio.Event()
+    e2 = asyncio.Event()
+
+    p = AsyncNullConnectionPool(dsn, max_size=1)
+    await p.wait()
+    success: List[str] = []
+
+    t1 = create_task(w1())
+    # Wait until w1 has received a connection
+    await e1.wait()
+
+    t2 = create_task(w2())
+    # Wait until w2 is in the queue
+    await ensure_waiting(p)
+    await p.close()
+
+    # Wait for the workers to finish
+    e2.set()
+    await asyncio.gather(t1, t2)
+    assert len(success) == 2
+
+
+async def test_open_explicit(dsn):
+    p = AsyncNullConnectionPool(dsn, open=False)
+    assert p.closed
+    with pytest.raises(PoolClosed):
+        await p.getconn()
+
+    with pytest.raises(PoolClosed, match="is not open yet"):
+        async with p.connection():
+            pass
+
+    await p.open()
+    try:
+        assert not p.closed
+
+        async with p.connection() as conn:
+            cur = await conn.execute("select 1")
+            assert await cur.fetchone() == (1,)
+
+    finally:
+        await p.close()
+
+    with pytest.raises(PoolClosed, match="is already closed"):
+        await p.getconn()
+
+
+async def test_open_context(dsn):
+    p = AsyncNullConnectionPool(dsn, open=False)
+    assert p.closed
+
+    async with p:
+        assert not p.closed
+
+        async with p.connection() as conn:
+            cur = await conn.execute("select 1")
+            assert await cur.fetchone() == (1,)
+
+    assert p.closed
+
+
+async def test_open_no_op(dsn):
+    p = AsyncNullConnectionPool(dsn)
+    try:
+        assert not p.closed
+        await p.open()
+        assert not p.closed
+
+        async with p.connection() as conn:
+            cur = await conn.execute("select 1")
+            assert await cur.fetchone() == (1,)
+
+    finally:
+        await p.close()
+
+
+async def test_reopen(dsn):
+    p = AsyncNullConnectionPool(dsn)
+    async with p.connection() as conn:
+        await conn.execute("select 1")
+    await p.close()
+    assert p._sched_runner is None
+
+    with pytest.raises(psycopg.OperationalError, match="cannot be reused"):
+        await p.open()
+
+
+@pytest.mark.parametrize("min_size, max_size", [(1, None), (-1, None), (0, -2)])
+async def test_bad_resize(dsn, min_size, max_size):
+    async with AsyncNullConnectionPool() as p:
+        with pytest.raises(ValueError):
+            await p.resize(min_size=min_size, max_size=max_size)
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.crdb_skip("backend pid")
+async def test_max_lifetime(dsn):
+    pids: List[int] = []
+
+    async def worker():
+        async with p.connection() as conn:
+            pids.append(conn.info.backend_pid)
+            await asyncio.sleep(0.1)
+
+    async with AsyncNullConnectionPool(dsn, max_size=1, max_lifetime=0.2) as p:
+        ts = [create_task(worker()) for i in range(5)]
+        await asyncio.gather(*ts)
+
+    assert pids[0] == pids[1] != pids[4], pids
+
+
+async def test_check(dsn):
+    # no.op
+    async with AsyncNullConnectionPool(dsn) as p:
+        await p.check()
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+async def test_stats_measures(dsn):
+    async def worker(n):
+        async with p.connection() as conn:
+            await conn.execute("select pg_sleep(0.2)")
+
+    async with AsyncNullConnectionPool(dsn, max_size=4) as p:
+        await p.wait(2.0)
+
+        stats = p.get_stats()
+        assert stats["pool_min"] == 0
+        assert stats["pool_max"] == 4
+        assert stats["pool_size"] == 0
+        assert stats["pool_available"] == 0
+        assert stats["requests_waiting"] == 0
+
+        ts = [create_task(worker(i)) for i in range(3)]
+        await asyncio.sleep(0.1)
+        stats = p.get_stats()
+        await asyncio.gather(*ts)
+        assert stats["pool_min"] == 0
+        assert stats["pool_max"] == 4
+        assert stats["pool_size"] == 3
+        assert stats["pool_available"] == 0
+        assert stats["requests_waiting"] == 0
+
+        await p.wait(2.0)
+        ts = [create_task(worker(i)) for i in range(7)]
+        await asyncio.sleep(0.1)
+        stats = p.get_stats()
+        await asyncio.gather(*ts)
+        assert stats["pool_min"] == 0
+        assert stats["pool_max"] == 4
+        assert stats["pool_size"] == 4
+        assert stats["pool_available"] == 0
+        assert stats["requests_waiting"] == 3
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+async def test_stats_usage(dsn):
+    async def worker(n):
+        try:
+            async with p.connection(timeout=0.3) as conn:
+                await conn.execute("select pg_sleep(0.2)")
+        except PoolTimeout:
+            pass
+
+    async with AsyncNullConnectionPool(dsn, max_size=3) as p:
+        await p.wait(2.0)
+
+        ts = [create_task(worker(i)) for i in range(7)]
+        await asyncio.gather(*ts)
+        stats = p.get_stats()
+        assert stats["requests_num"] == 7
+        assert stats["requests_queued"] == 4
+        assert 850 <= stats["requests_wait_ms"] <= 950
+        assert stats["requests_errors"] == 1
+        assert 1150 <= stats["usage_ms"] <= 1250
+        assert stats.get("returns_bad", 0) == 0
+
+        async with p.connection() as conn:
+            await conn.close()
+        await p.wait()
+        stats = p.pop_stats()
+        assert stats["requests_num"] == 8
+        assert stats["returns_bad"] == 1
+        async with p.connection():
+            pass
+        assert p.get_stats()["requests_num"] == 1
+
+
+@pytest.mark.slow
+async def test_stats_connect(dsn, proxy, monkeypatch):
+    proxy.start()
+    delay_connection(monkeypatch, 0.2)
+    async with AsyncNullConnectionPool(proxy.client_dsn, max_size=3) as p:
+        await p.wait()
+        stats = p.get_stats()
+        assert stats["connections_num"] == 1
+        assert stats.get("connections_errors", 0) == 0
+        assert stats.get("connections_lost", 0) == 0
+        assert 200 <= stats["connections_ms"] < 300
diff --git a/tests/pool/test_pool.py b/tests/pool/test_pool.py
new file mode 100644
index 0000000..30c790b
--- /dev/null
+++ b/tests/pool/test_pool.py
@@ -0,0 +1,1265 @@
+import logging
+import weakref
+from time import sleep, time
+from threading import Thread, Event
+from typing import Any, List, Tuple
+
+import pytest
+
+import psycopg
+from psycopg.pq import TransactionStatus
+from psycopg._compat import Counter
+
+try:
+    import psycopg_pool as pool
+except ImportError:
+    # Tests should have been skipped if the package is not available
+    pass
+
+
+def test_package_version(mypy):
+    cp = mypy.run_on_source(
+        """\
+from psycopg_pool import __version__
+assert __version__
+"""
+    )
+    assert not cp.stdout
+
+
+def test_defaults(dsn):
+    with pool.ConnectionPool(dsn) as p:
+        assert p.min_size == p.max_size == 4
+        assert p.timeout == 30
+        assert p.max_idle == 10 * 60
+        assert p.max_lifetime == 60 * 60
+        assert p.num_workers == 3
+
+
+@pytest.mark.parametrize("min_size, max_size", [(2, None), (0, 2), (2, 4)])
+def test_min_size_max_size(dsn, min_size, max_size):
+    with pool.ConnectionPool(dsn, min_size=min_size, max_size=max_size) as p:
+        assert p.min_size == min_size
+        assert p.max_size == max_size if max_size is not None else min_size
+
+
+@pytest.mark.parametrize("min_size, max_size", [(0, 0), (0, None), (-1, None), (4, 2)])
+def test_bad_size(dsn, min_size, max_size):
+    with pytest.raises(ValueError):
+        pool.ConnectionPool(min_size=min_size, max_size=max_size)
+
+
+def test_connection_class(dsn):
+    class MyConn(psycopg.Connection[Any]):
+        pass
+
+    with pool.ConnectionPool(dsn, connection_class=MyConn, min_size=1) as p:
+        with p.connection() as conn:
+            assert isinstance(conn, MyConn)
+
+
+def test_kwargs(dsn):
+    with pool.ConnectionPool(dsn, kwargs={"autocommit": True}, min_size=1) as p:
+        with p.connection() as conn:
+            assert conn.autocommit
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_its_really_a_pool(dsn):
+    with pool.ConnectionPool(dsn, min_size=2) as p:
+        with p.connection() as conn:
+            pid1 = conn.info.backend_pid
+
+            with p.connection() as conn2:
+                pid2 = conn2.info.backend_pid
+
+        with p.connection() as conn:
+            assert conn.info.backend_pid in (pid1, pid2)
+
+
+def test_context(dsn):
+    with pool.ConnectionPool(dsn, min_size=1) as p:
+        assert not p.closed
+    assert p.closed
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_connection_not_lost(dsn):
+    with pool.ConnectionPool(dsn, min_size=1) as p:
+        with pytest.raises(ZeroDivisionError):
+            with p.connection() as conn:
+                pid = conn.info.backend_pid
+                1 / 0
+
+        with p.connection() as conn2:
+            assert conn2.info.backend_pid == pid
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+def test_concurrent_filling(dsn, monkeypatch):
+    delay_connection(monkeypatch, 0.1)
+
+    def add_time(self, conn):
+        times.append(time() - t0)
+        add_orig(self, conn)
+
+    add_orig = pool.ConnectionPool._add_to_pool
+    monkeypatch.setattr(pool.ConnectionPool, "_add_to_pool", add_time)
+
+    times: List[float] = []
+    t0 = time()
+
+    with pool.ConnectionPool(dsn, min_size=5, num_workers=2) as p:
+        p.wait(1.0)
+        want_times = [0.1, 0.1, 0.2, 0.2, 0.3]
+        assert len(times) == len(want_times)
+        for got, want in zip(times, want_times):
+            assert got == pytest.approx(want, 0.1), times
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+def test_wait_ready(dsn, monkeypatch):
+    delay_connection(monkeypatch, 0.1)
+    with pytest.raises(pool.PoolTimeout):
+        with pool.ConnectionPool(dsn, min_size=4, num_workers=1) as p:
+            p.wait(0.3)
+
+    with pool.ConnectionPool(dsn, min_size=4, num_workers=1) as p:
+        p.wait(0.5)
+
+    with pool.ConnectionPool(dsn, min_size=4, num_workers=2) as p:
+        p.wait(0.3)
+        p.wait(0.0001)  # idempotent
+
+
+def test_wait_closed(dsn):
+    with pool.ConnectionPool(dsn) as p:
+        pass
+
+    with pytest.raises(pool.PoolClosed):
+        p.wait()
+
+
+@pytest.mark.slow
+def test_setup_no_timeout(dsn, proxy):
+    with pytest.raises(pool.PoolTimeout):
+        with pool.ConnectionPool(proxy.client_dsn, min_size=1, num_workers=1) as p:
+            p.wait(0.2)
+
+    with pool.ConnectionPool(proxy.client_dsn, min_size=1, num_workers=1) as p:
+        sleep(0.5)
+        assert not p._pool
+        proxy.start()
+
+        with p.connection() as conn:
+            conn.execute("select 1")
+
+
+def test_configure(dsn):
+    inits = 0
+
+    def configure(conn):
+        nonlocal inits
+        inits += 1
+        with conn.transaction():
+            conn.execute("set default_transaction_read_only to on")
+
+    with pool.ConnectionPool(dsn, min_size=1, configure=configure) as p:
+        p.wait()
+        with p.connection() as conn:
+            assert inits == 1
+            res = conn.execute("show default_transaction_read_only")
+            assert res.fetchone()[0] == "on"  # type: ignore[index]
+
+        with p.connection() as conn:
+            assert inits == 1
+            res = conn.execute("show default_transaction_read_only")
+            assert res.fetchone()[0] == "on"  # type: ignore[index]
+            conn.close()
+
+        with p.connection() as conn:
+            assert inits == 2
+            res = conn.execute("show default_transaction_read_only")
+            assert res.fetchone()[0] == "on"  # type: ignore[index]
+
+
+@pytest.mark.slow
+def test_configure_badstate(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    def configure(conn):
+        conn.execute("select 1")
+
+    with pool.ConnectionPool(dsn, min_size=1, configure=configure) as p:
+        with pytest.raises(pool.PoolTimeout):
+            p.wait(timeout=0.5)
+
+    assert caplog.records
+    assert "INTRANS" in caplog.records[0].message
+
+
+@pytest.mark.slow
+def test_configure_broken(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    def configure(conn):
+        with conn.transaction():
+            conn.execute("WAT")
+
+    with pool.ConnectionPool(dsn, min_size=1, configure=configure) as p:
+        with pytest.raises(pool.PoolTimeout):
+            p.wait(timeout=0.5)
+
+    assert caplog.records
+    assert "WAT" in caplog.records[0].message
+
+
+def test_reset(dsn):
+    resets = 0
+
+    def setup(conn):
+        with conn.transaction():
+            conn.execute("set timezone to '+1:00'")
+
+    def reset(conn):
+        nonlocal resets
+        resets += 1
+        with conn.transaction():
+            conn.execute("set timezone to utc")
+
+    with pool.ConnectionPool(dsn, min_size=1, reset=reset) as p:
+        with p.connection() as conn:
+            assert resets == 0
+            conn.execute("set timezone to '+2:00'")
+
+        p.wait()
+        assert resets == 1
+
+        with p.connection() as conn:
+            with conn.execute("show timezone") as cur:
+                assert cur.fetchone() == ("UTC",)
+
+        p.wait()
+        assert resets == 2
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_reset_badstate(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    def reset(conn):
+        conn.execute("reset all")
+
+    with pool.ConnectionPool(dsn, min_size=1, reset=reset) as p:
+        with p.connection() as conn:
+            conn.execute("select 1")
+            pid1 = conn.info.backend_pid
+
+        with p.connection() as conn:
+            conn.execute("select 1")
+            pid2 = conn.info.backend_pid
+
+    assert pid1 != pid2
+    assert caplog.records
+    assert "INTRANS" in caplog.records[0].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_reset_broken(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    def reset(conn):
+        with conn.transaction():
+            conn.execute("WAT")
+
+    with pool.ConnectionPool(dsn, min_size=1, reset=reset) as p:
+        with p.connection() as conn:
+            conn.execute("select 1")
+            pid1 = conn.info.backend_pid
+
+        with p.connection() as conn:
+            conn.execute("select 1")
+            pid2 = conn.info.backend_pid
+
+    assert pid1 != pid2
+    assert caplog.records
+    assert "WAT" in caplog.records[0].message
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.crdb_skip("backend pid")
+def test_queue(dsn):
+    def worker(n):
+        t0 = time()
+        with p.connection() as conn:
+            conn.execute("select pg_sleep(0.2)")
+            pid = conn.info.backend_pid
+        t1 = time()
+        results.append((n, t1 - t0, pid))
+
+    results: List[Tuple[int, float, int]] = []
+    with pool.ConnectionPool(dsn, min_size=2) as p:
+        p.wait()
+        ts = [Thread(target=worker, args=(i,)) for i in range(6)]
+        for t in ts:
+            t.start()
+        for t in ts:
+            t.join()
+
+    times = [item[1] for item in results]
+    want_times = [0.2, 0.2, 0.4, 0.4, 0.6, 0.6]
+    for got, want in zip(times, want_times):
+        assert got == pytest.approx(want, 0.1), times
+
+    assert len(set(r[2] for r in results)) == 2, results
+
+
+@pytest.mark.slow
+def test_queue_size(dsn):
+    def worker(t, ev=None):
+        try:
+            with p.connection():
+                if ev:
+                    ev.set()
+                sleep(t)
+        except pool.TooManyRequests as e:
+            errors.append(e)
+        else:
+            success.append(True)
+
+    errors: List[Exception] = []
+    success: List[bool] = []
+
+    with pool.ConnectionPool(dsn, min_size=1, max_waiting=3) as p:
+        p.wait()
+        ev = Event()
+        t = Thread(target=worker, args=(0.3, ev))
+        t.start()
+        ev.wait()
+
+        ts = [Thread(target=worker, args=(0.1,)) for i in range(4)]
+        for t in ts:
+            t.start()
+        for t in ts:
+            t.join()
+
+    assert len(success) == 4
+    assert len(errors) == 1
+    assert isinstance(errors[0], pool.TooManyRequests)
+    assert p.name in str(errors[0])
+    assert str(p.max_waiting) in str(errors[0])
+    assert p.get_stats()["requests_errors"] == 1
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.crdb_skip("backend pid")
+def test_queue_timeout(dsn):
+    def worker(n):
+        t0 = time()
+        try:
+            with p.connection() as conn:
+                conn.execute("select pg_sleep(0.2)")
+                pid = conn.info.backend_pid
+        except pool.PoolTimeout as e:
+            t1 = time()
+            errors.append((n, t1 - t0, e))
+        else:
+            t1 = time()
+            results.append((n, t1 - t0, pid))
+
+    results: List[Tuple[int, float, int]] = []
+    errors: List[Tuple[int, float, Exception]] = []
+
+    with pool.ConnectionPool(dsn, min_size=2, timeout=0.1) as p:
+        ts = [Thread(target=worker, args=(i,)) for i in range(4)]
+        for t in ts:
+            t.start()
+        for t in ts:
+            t.join()
+
+    assert len(results) == 2
+    assert len(errors) == 2
+    for e in errors:
+        assert 0.1 < e[1] < 0.15
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+def test_dead_client(dsn):
+    def worker(i, timeout):
+        try:
+            with p.connection(timeout=timeout) as conn:
+                conn.execute("select pg_sleep(0.3)")
+                results.append(i)
+        except pool.PoolTimeout:
+            if timeout > 0.2:
+                raise
+
+    results: List[int] = []
+
+    with pool.ConnectionPool(dsn, min_size=2) as p:
+        ts = [
+            Thread(target=worker, args=(i, timeout))
+            for i, timeout in enumerate([0.4, 0.4, 0.1, 0.4, 0.4])
+        ]
+        for t in ts:
+            t.start()
+        for t in ts:
+            t.join()
+        sleep(0.2)
+        assert set(results) == set([0, 1, 3, 4])
+        assert len(p._pool) == 2  # no connection was lost
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.crdb_skip("backend pid")
+def test_queue_timeout_override(dsn):
+    def worker(n):
+        t0 = time()
+        timeout = 0.25 if n == 3 else None
+        try:
+            with p.connection(timeout=timeout) as conn:
+                conn.execute("select pg_sleep(0.2)")
+                pid = conn.info.backend_pid
+        except pool.PoolTimeout as e:
+            t1 = time()
+            errors.append((n, t1 - t0, e))
+        else:
+            t1 = time()
+            results.append((n, t1 - t0, pid))
+
+    results: List[Tuple[int, float, int]] = []
+    errors: List[Tuple[int, float, Exception]] = []
+
+    with pool.ConnectionPool(dsn, min_size=2, timeout=0.1) as p:
+        ts = [Thread(target=worker, args=(i,)) for i in range(4)]
+        for t in ts:
+            t.start()
+        for t in ts:
+            t.join()
+
+    assert len(results) == 3
+    assert len(errors) == 1
+    for e in errors:
+        assert 0.1 < e[1] < 0.15
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_broken_reconnect(dsn):
+    with pool.ConnectionPool(dsn, min_size=1) as p:
+        with p.connection() as conn:
+            pid1 = conn.info.backend_pid
+            conn.close()
+
+        with p.connection() as conn2:
+            pid2 = conn2.info.backend_pid
+
+    assert pid1 != pid2
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_intrans_rollback(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    with pool.ConnectionPool(dsn, min_size=1) as p:
+        conn = p.getconn()
+        pid = conn.info.backend_pid
+        conn.execute("create table test_intrans_rollback ()")
+        assert conn.info.transaction_status == TransactionStatus.INTRANS
+        p.putconn(conn)
+
+        with p.connection() as conn2:
+            assert conn2.info.backend_pid == pid
+            assert conn2.info.transaction_status == TransactionStatus.IDLE
+            assert not conn2.execute(
+                "select 1 from pg_class where relname = 'test_intrans_rollback'"
+            ).fetchone()
+
+    assert len(caplog.records) == 1
+    assert "INTRANS" in caplog.records[0].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_inerror_rollback(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    with pool.ConnectionPool(dsn, min_size=1) as p:
+        conn = p.getconn()
+        pid = conn.info.backend_pid
+        with pytest.raises(psycopg.ProgrammingError):
+            conn.execute("wat")
+        assert conn.info.transaction_status == TransactionStatus.INERROR
+        p.putconn(conn)
+
+        with p.connection() as conn2:
+            assert conn2.info.backend_pid == pid
+            assert conn2.info.transaction_status == TransactionStatus.IDLE
+
+    assert len(caplog.records) == 1
+    assert "INERROR" in caplog.records[0].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+@pytest.mark.crdb_skip("copy")
+def test_active_close(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    with pool.ConnectionPool(dsn, min_size=1) as p:
+        conn = p.getconn()
+        pid = conn.info.backend_pid
+        conn.pgconn.exec_(b"copy (select * from generate_series(1, 10)) to stdout")
+        assert conn.info.transaction_status == TransactionStatus.ACTIVE
+        p.putconn(conn)
+
+        with p.connection() as conn2:
+            assert conn2.info.backend_pid != pid
+            assert conn2.info.transaction_status == TransactionStatus.IDLE
+
+    assert len(caplog.records) == 2
+    assert "ACTIVE" in caplog.records[0].message
+    assert "BAD" in caplog.records[1].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_fail_rollback_close(dsn, caplog, monkeypatch):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    with pool.ConnectionPool(dsn, min_size=1) as p:
+        conn = p.getconn()
+
+        def bad_rollback():
+            conn.pgconn.finish()
+            orig_rollback()
+
+        # Make the rollback fail
+        orig_rollback = conn.rollback
+        monkeypatch.setattr(conn, "rollback", bad_rollback)
+
+        pid = conn.info.backend_pid
+        with pytest.raises(psycopg.ProgrammingError):
+            conn.execute("wat")
+        assert conn.info.transaction_status == TransactionStatus.INERROR
+        p.putconn(conn)
+
+        with p.connection() as conn2:
+            assert conn2.info.backend_pid != pid
+            assert conn2.info.transaction_status == TransactionStatus.IDLE
+
+    assert len(caplog.records) == 3
+    assert "INERROR" in caplog.records[0].message
+    assert "OperationalError" in caplog.records[1].message
+    assert "BAD" in caplog.records[2].message
+
+
+def test_close_no_threads(dsn):
+    p = pool.ConnectionPool(dsn)
+    assert p._sched_runner and p._sched_runner.is_alive()
+    workers = p._workers[:]
+    assert workers
+    for t in workers:
+        assert t.is_alive()
+
+    p.close()
+    assert p._sched_runner is None
+    assert not p._workers
+    for t in workers:
+        assert not t.is_alive()
+
+
+def test_putconn_no_pool(conn_cls, dsn):
+    with pool.ConnectionPool(dsn, min_size=1) as p:
+        conn = conn_cls.connect(dsn)
+        with pytest.raises(ValueError):
+            p.putconn(conn)
+
+    conn.close()
+
+
+def test_putconn_wrong_pool(dsn):
+    with pool.ConnectionPool(dsn, min_size=1) as p1:
+        with pool.ConnectionPool(dsn, min_size=1) as p2:
+            conn = p1.getconn()
+            with pytest.raises(ValueError):
+                p2.putconn(conn)
+
+
+def test_del_no_warning(dsn, recwarn):
+    p = pool.ConnectionPool(dsn, min_size=2)
+    with p.connection() as conn:
+        conn.execute("select 1")
+
+    p.wait()
+    ref = weakref.ref(p)
+    del p
+    assert not ref()
+    assert not recwarn, [str(w.message) for w in recwarn.list]
+
+
+@pytest.mark.slow
+def test_del_stop_threads(dsn):
+    p = pool.ConnectionPool(dsn)
+    assert p._sched_runner is not None
+    ts = [p._sched_runner] + p._workers
+    del p
+    sleep(0.1)
+    for t in ts:
+        assert not t.is_alive()
+
+
+def test_closed_getconn(dsn):
+    p = pool.ConnectionPool(dsn, min_size=1)
+    assert not p.closed
+    with p.connection():
+        pass
+
+    p.close()
+    assert p.closed
+
+    with pytest.raises(pool.PoolClosed):
+        with p.connection():
+            pass
+
+
+def test_closed_putconn(dsn):
+    p = pool.ConnectionPool(dsn, min_size=1)
+
+    with p.connection() as conn:
+        pass
+    assert not conn.closed
+
+    with p.connection() as conn:
+        p.close()
+    assert conn.closed
+
+
+def test_closed_queue(dsn):
+    def w1():
+        with p.connection() as conn:
+            e1.set()  # Tell w0 that w1 got a connection
+            cur = conn.execute("select 1")
+            assert cur.fetchone() == (1,)
+            e2.wait()  # Wait until w0 has tested w2
+        success.append("w1")
+
+    def w2():
+        try:
+            with p.connection():
+                pass  # unexpected
+        except pool.PoolClosed:
+            success.append("w2")
+
+    e1 = Event()
+    e2 = Event()
+
+    p = pool.ConnectionPool(dsn, min_size=1)
+    p.wait()
+    success: List[str] = []
+
+    t1 = Thread(target=w1)
+    t1.start()
+    # Wait until w1 has received a connection
+    e1.wait()
+
+    t2 = Thread(target=w2)
+    t2.start()
+    # Wait until w2 is in the queue
+    ensure_waiting(p)
+
+    p.close(0)
+
+    # Wait for the workers to finish
+    e2.set()
+    t1.join()
+    t2.join()
+    assert len(success) == 2
+
+
+def test_open_explicit(dsn):
+    p = pool.ConnectionPool(dsn, open=False)
+    assert p.closed
+    with pytest.raises(pool.PoolClosed, match="is not open yet"):
+        p.getconn()
+
+    with pytest.raises(pool.PoolClosed):
+        with p.connection():
+            pass
+
+    p.open()
+    try:
+        assert not p.closed
+
+        with p.connection() as conn:
+            cur = conn.execute("select 1")
+            assert cur.fetchone() == (1,)
+
+    finally:
+        p.close()
+
+    with pytest.raises(pool.PoolClosed, match="is already closed"):
+        p.getconn()
+
+
+def test_open_context(dsn):
+    p = pool.ConnectionPool(dsn, open=False)
+    assert p.closed
+
+    with p:
+        assert not p.closed
+
+        with p.connection() as conn:
+            cur = conn.execute("select 1")
+            assert cur.fetchone() == (1,)
+
+    assert p.closed
+
+
+def test_open_no_op(dsn):
+    p = pool.ConnectionPool(dsn)
+    try:
+        assert not p.closed
+        p.open()
+        assert not p.closed
+
+        with p.connection() as conn:
+            cur = conn.execute("select 1")
+            assert cur.fetchone() == (1,)
+
+    finally:
+        p.close()
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+def test_open_wait(dsn, monkeypatch):
+    delay_connection(monkeypatch, 0.1)
+    with pytest.raises(pool.PoolTimeout):
+        p = pool.ConnectionPool(dsn, min_size=4, num_workers=1, open=False)
+        try:
+            p.open(wait=True, timeout=0.3)
+        finally:
+            p.close()
+
+    p = pool.ConnectionPool(dsn, min_size=4, num_workers=1, open=False)
+    try:
+        p.open(wait=True, timeout=0.5)
+    finally:
+        p.close()
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+def test_open_as_wait(dsn, monkeypatch):
+    delay_connection(monkeypatch, 0.1)
+    with pytest.raises(pool.PoolTimeout):
+        with pool.ConnectionPool(dsn, min_size=4, num_workers=1) as p:
+            p.open(wait=True, timeout=0.3)
+
+    with pool.ConnectionPool(dsn, min_size=4, num_workers=1) as p:
+        p.open(wait=True, timeout=0.5)
+
+
+def test_reopen(dsn):
+    p = pool.ConnectionPool(dsn)
+    with p.connection() as conn:
+        conn.execute("select 1")
+    p.close()
+    assert p._sched_runner is None
+    assert not p._workers
+
+    with pytest.raises(psycopg.OperationalError, match="cannot be reused"):
+        p.open()
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.parametrize(
+    "min_size, want_times",
+    [
+        (2, [0.25, 0.25, 0.35, 0.45, 0.50, 0.50, 0.60, 0.70]),
+        (0, [0.35, 0.45, 0.55, 0.60, 0.65, 0.70, 0.80, 0.85]),
+    ],
+)
+def test_grow(dsn, monkeypatch, min_size, want_times):
+    delay_connection(monkeypatch, 0.1)
+
+    def worker(n):
+        t0 = time()
+        with p.connection() as conn:
+            conn.execute("select 1 from pg_sleep(0.25)")
+        t1 = time()
+        results.append((n, t1 - t0))
+
+    with pool.ConnectionPool(dsn, min_size=min_size, max_size=4, num_workers=3) as p:
+        p.wait(1.0)
+        results: List[Tuple[int, float]] = []
+
+        ts = [Thread(target=worker, args=(i,)) for i in range(len(want_times))]
+        for t in ts:
+            t.start()
+        for t in ts:
+            t.join()
+
+    times = [item[1] for item in results]
+    for got, want in zip(times, want_times):
+        assert got == pytest.approx(want, 0.1), times
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+def test_shrink(dsn, monkeypatch):
+
+    from psycopg_pool.pool import ShrinkPool
+
+    results: List[Tuple[int, int]] = []
+
+    def run_hacked(self, pool):
+        n0 = pool._nconns
+        orig_run(self, pool)
+        n1 = pool._nconns
+        results.append((n0, n1))
+
+    orig_run = ShrinkPool._run
+    monkeypatch.setattr(ShrinkPool, "_run", run_hacked)
+
+    def worker(n):
+        with p.connection() as conn:
+            conn.execute("select pg_sleep(0.1)")
+
+    with pool.ConnectionPool(dsn, min_size=2, max_size=4, max_idle=0.2) as p:
+        p.wait(5.0)
+        assert p.max_idle == 0.2
+
+        ts = [Thread(target=worker, args=(i,)) for i in range(4)]
+        for t in ts:
+            t.start()
+        for t in ts:
+            t.join()
+        sleep(1)
+
+    assert results == [(4, 4), (4, 3), (3, 2), (2, 2), (2, 2)]
+
+
+@pytest.mark.slow
+def test_reconnect(proxy, caplog, monkeypatch):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    assert pool.base.ConnectionAttempt.INITIAL_DELAY == 1.0
+    assert pool.base.ConnectionAttempt.DELAY_JITTER == 0.1
+    monkeypatch.setattr(pool.base.ConnectionAttempt, "INITIAL_DELAY", 0.1)
+    monkeypatch.setattr(pool.base.ConnectionAttempt, "DELAY_JITTER", 0.0)
+
+    caplog.clear()
+    proxy.start()
+    with pool.ConnectionPool(proxy.client_dsn, min_size=1) as p:
+        p.wait(2.0)
+        proxy.stop()
+
+        with pytest.raises(psycopg.OperationalError):
+            with p.connection() as conn:
+                conn.execute("select 1")
+
+        sleep(1.0)
+        proxy.start()
+        p.wait()
+
+        with p.connection() as conn:
+            conn.execute("select 1")
+
+    assert "BAD" in caplog.messages[0]
+    times = [rec.created for rec in caplog.records]
+    assert times[1] - times[0] < 0.05
+    deltas = [times[i + 1] - times[i] for i in range(1, len(times) - 1)]
+    assert len(deltas) == 3
+    want = 0.1
+    for delta in deltas:
+        assert delta == pytest.approx(want, 0.05), deltas
+        want *= 2
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+def test_reconnect_failure(proxy):
+    proxy.start()
+
+    t1 = None
+
+    def failed(pool):
+        assert pool.name == "this-one"
+        nonlocal t1
+        t1 = time()
+
+    with pool.ConnectionPool(
+        proxy.client_dsn,
+        name="this-one",
+        min_size=1,
+        reconnect_timeout=1.0,
+        reconnect_failed=failed,
+    ) as p:
+        p.wait(2.0)
+        proxy.stop()
+
+        with pytest.raises(psycopg.OperationalError):
+            with p.connection() as conn:
+                conn.execute("select 1")
+
+        t0 = time()
+        sleep(1.5)
+        assert t1
+        assert t1 - t0 == pytest.approx(1.0, 0.1)
+        assert p._nconns == 0
+
+        proxy.start()
+        t0 = time()
+        with p.connection() as conn:
+            conn.execute("select 1")
+        t1 = time()
+        assert t1 - t0 < 0.2
+
+
+@pytest.mark.slow
+def test_reconnect_after_grow_failed(proxy):
+    # Retry reconnection after a failed connection attempt has put the pool
+    # in grow mode. See issue #370.
+    proxy.stop()
+
+    ev = Event()
+
+    def failed(pool):
+        ev.set()
+
+    with pool.ConnectionPool(
+        proxy.client_dsn, min_size=4, reconnect_timeout=1.0, reconnect_failed=failed
+    ) as p:
+        assert ev.wait(timeout=2)
+
+        with pytest.raises(pool.PoolTimeout):
+            with p.connection(timeout=0.5) as conn:
+                pass
+
+        ev.clear()
+        assert ev.wait(timeout=2)
+
+        proxy.start()
+
+        with p.connection(timeout=2) as conn:
+            conn.execute("select 1")
+
+        p.wait(timeout=3.0)
+        assert len(p._pool) == p.min_size == 4
+
+
+@pytest.mark.slow
+def test_refill_on_check(proxy):
+    proxy.start()
+    ev = Event()
+
+    def failed(pool):
+        ev.set()
+
+    with pool.ConnectionPool(
+        proxy.client_dsn, min_size=4, reconnect_timeout=1.0, reconnect_failed=failed
+    ) as p:
+        # The pool is full
+        p.wait(timeout=2)
+
+        # Break all the connection
+        proxy.stop()
+
+        # Checking the pool will empty it
+        p.check()
+        assert ev.wait(timeout=2)
+        assert len(p._pool) == 0
+
+        # Allow to connect again
+        proxy.start()
+
+        # Make sure that check has refilled the pool
+        p.check()
+        p.wait(timeout=2)
+        assert len(p._pool) == 4
+
+
+@pytest.mark.slow
+def test_uniform_use(dsn):
+    with pool.ConnectionPool(dsn, min_size=4) as p:
+        counts = Counter[int]()
+        for i in range(8):
+            with p.connection() as conn:
+                sleep(0.1)
+                counts[id(conn)] += 1
+
+    assert len(counts) == 4
+    assert set(counts.values()) == set([2])
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+def test_resize(dsn):
+    def sampler():
+        sleep(0.05)  # ensure sampling happens after shrink check
+        while True:
+            sleep(0.2)
+            if p.closed:
+                break
+            size.append(len(p._pool))
+
+    def client(t):
+        with p.connection() as conn:
+            conn.execute("select pg_sleep(%s)", [t])
+
+    size: List[int] = []
+
+    with pool.ConnectionPool(dsn, min_size=2, max_idle=0.2) as p:
+        s = Thread(target=sampler)
+        s.start()
+
+        sleep(0.3)
+        c = Thread(target=client, args=(0.4,))
+        c.start()
+
+        sleep(0.2)
+        p.resize(4)
+        assert p.min_size == 4
+        assert p.max_size == 4
+
+        sleep(0.4)
+        p.resize(2)
+        assert p.min_size == 2
+        assert p.max_size == 2
+
+        sleep(0.6)
+
+    s.join()
+    assert size == [2, 1, 3, 4, 3, 2, 2]
+
+
+@pytest.mark.parametrize("min_size, max_size", [(0, 0), (-1, None), (4, 2)])
+def test_bad_resize(dsn, min_size, max_size):
+    with pool.ConnectionPool() as p:
+        with pytest.raises(ValueError):
+            p.resize(min_size=min_size, max_size=max_size)
+
+
+def test_jitter():
+    rnds = [pool.ConnectionPool._jitter(30, -0.1, +0.2) for i in range(100)]
+    assert 27 <= min(rnds) <= 28
+    assert 35 < max(rnds) < 36
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.crdb_skip("backend pid")
+def test_max_lifetime(dsn):
+    with pool.ConnectionPool(dsn, min_size=1, max_lifetime=0.2) as p:
+        sleep(0.1)
+        pids = []
+        for i in range(5):
+            with p.connection() as conn:
+                pids.append(conn.info.backend_pid)
+            sleep(0.2)
+
+    assert pids[0] == pids[1] != pids[4], pids
+
+
+@pytest.mark.crdb_skip("backend pid")
+def test_check(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+    with pool.ConnectionPool(dsn, min_size=4) as p:
+        p.wait(1.0)
+        with p.connection() as conn:
+            pid = conn.info.backend_pid
+
+        p.wait(1.0)
+        pids = set(conn.info.backend_pid for conn in p._pool)
+        assert pid in pids
+        conn.close()
+
+        assert len(caplog.records) == 0
+        p.check()
+        assert len(caplog.records) == 1
+        p.wait(1.0)
+        pids2 = set(conn.info.backend_pid for conn in p._pool)
+        assert len(pids & pids2) == 3
+        assert pid not in pids2
+
+
+def test_check_idle(dsn):
+    with pool.ConnectionPool(dsn, min_size=2) as p:
+        p.wait(1.0)
+        p.check()
+        with p.connection() as conn:
+            assert conn.info.transaction_status == TransactionStatus.IDLE
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+def test_stats_measures(dsn):
+    def worker(n):
+        with p.connection() as conn:
+            conn.execute("select pg_sleep(0.2)")
+
+    with pool.ConnectionPool(dsn, min_size=2, max_size=4) as p:
+        p.wait(2.0)
+
+        stats = p.get_stats()
+        assert stats["pool_min"] == 2
+        assert stats["pool_max"] == 4
+        assert stats["pool_size"] == 2
+        assert stats["pool_available"] == 2
+        assert stats["requests_waiting"] == 0
+
+        ts = [Thread(target=worker, args=(i,)) for i in range(3)]
+        for t in ts:
+            t.start()
+        sleep(0.1)
+        stats = p.get_stats()
+        for t in ts:
+            t.join()
+        assert stats["pool_min"] == 2
+        assert stats["pool_max"] == 4
+        assert stats["pool_size"] == 3
+        assert stats["pool_available"] == 0
+        assert stats["requests_waiting"] == 0
+
+        p.wait(2.0)
+        ts = [Thread(target=worker, args=(i,)) for i in range(7)]
+        for t in ts:
+            t.start()
+        sleep(0.1)
+        stats = p.get_stats()
+        for t in ts:
+            t.join()
+        assert stats["pool_min"] == 2
+        assert stats["pool_max"] == 4
+        assert stats["pool_size"] == 4
+        assert stats["pool_available"] == 0
+        assert stats["requests_waiting"] == 3
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+def test_stats_usage(dsn):
+    def worker(n):
+        try:
+            with p.connection(timeout=0.3) as conn:
+                conn.execute("select pg_sleep(0.2)")
+        except pool.PoolTimeout:
+            pass
+
+    with pool.ConnectionPool(dsn, min_size=3) as p:
+        p.wait(2.0)
+
+        ts = [Thread(target=worker, args=(i,)) for i in range(7)]
+        for t in ts:
+            t.start()
+        for t in ts:
+            t.join()
+        stats = p.get_stats()
+        assert stats["requests_num"] == 7
+        assert stats["requests_queued"] == 4
+        assert 850 <= stats["requests_wait_ms"] <= 950
+        assert stats["requests_errors"] == 1
+        assert 1150 <= stats["usage_ms"] <= 1250
+        assert stats.get("returns_bad", 0) == 0
+
+        with p.connection() as conn:
+            conn.close()
+        p.wait()
+        stats = p.pop_stats()
+        assert stats["requests_num"] == 8
+        assert stats["returns_bad"] == 1
+        with p.connection():
+            pass
+        assert p.get_stats()["requests_num"] == 1
+
+
+@pytest.mark.slow
+def test_stats_connect(dsn, proxy, monkeypatch):
+    proxy.start()
+    delay_connection(monkeypatch, 0.2)
+    with pool.ConnectionPool(proxy.client_dsn, min_size=3) as p:
+        p.wait()
+        stats = p.get_stats()
+        assert stats["connections_num"] == 3
+        assert stats.get("connections_errors", 0) == 0
+        assert stats.get("connections_lost", 0) == 0
+        assert 600 <= stats["connections_ms"] < 1200
+
+        proxy.stop()
+        p.check()
+        sleep(0.1)
+        stats = p.get_stats()
+        assert stats["connections_num"] > 3
+        assert stats["connections_errors"] > 0
+        assert stats["connections_lost"] == 3
+
+
+@pytest.mark.slow
+def test_spike(dsn, monkeypatch):
+    # Inspired to https://github.com/brettwooldridge/HikariCP/blob/dev/
+    # documents/Welcome-To-The-Jungle.md
+    delay_connection(monkeypatch, 0.15)
+
+    def worker():
+        with p.connection():
+            sleep(0.002)
+
+    with pool.ConnectionPool(dsn, min_size=5, max_size=10) as p:
+        p.wait()
+
+        ts = [Thread(target=worker) for i in range(50)]
+        for t in ts:
+            t.start()
+        for t in ts:
+            t.join()
+        p.wait()
+
+        assert len(p._pool) < 7
+
+
+def test_debug_deadlock(dsn):
+    # https://github.com/psycopg/psycopg/issues/230
+    logger = logging.getLogger("psycopg")
+    handler = logging.StreamHandler()
+    old_level = logger.level
+    logger.setLevel(logging.DEBUG)
+    handler.setLevel(logging.DEBUG)
+    logger.addHandler(handler)
+    try:
+        with pool.ConnectionPool(dsn, min_size=4, open=True) as p:
+            try:
+                p.wait(timeout=2)
+            finally:
+                print(p.get_stats())
+    finally:
+        logger.removeHandler(handler)
+        logger.setLevel(old_level)
+
+
+def delay_connection(monkeypatch, sec):
+    """
+    Return a _connect_gen function delayed by the amount of seconds
+    """
+
+    def connect_delay(*args, **kwargs):
+        t0 = time()
+        rv = connect_orig(*args, **kwargs)
+        t1 = time()
+        sleep(max(0, sec - (t1 - t0)))
+        return rv
+
+    connect_orig = psycopg.Connection.connect
+    monkeypatch.setattr(psycopg.Connection, "connect", connect_delay)
+
+
+def ensure_waiting(p, num=1):
+    """
+    Wait until there are at least *num* clients waiting in the queue.
+    """
+    while len(p._waiting) < num:
+        sleep(0)
diff --git a/tests/pool/test_pool_async.py b/tests/pool/test_pool_async.py
new file mode 100644
index 0000000..286a775
--- /dev/null
+++ b/tests/pool/test_pool_async.py
@@ -0,0 +1,1198 @@
+import asyncio
+import logging
+from time import time
+from typing import Any, List, Tuple
+
+import pytest
+
+import psycopg
+from psycopg.pq import TransactionStatus
+from psycopg._compat import create_task, Counter
+
+try:
+    import psycopg_pool as pool
+except ImportError:
+    # Tests should have been skipped if the package is not available
+    pass
+
+pytestmark = [pytest.mark.asyncio]
+
+
+async def test_defaults(dsn):
+    async with pool.AsyncConnectionPool(dsn) as p:
+        assert p.min_size == p.max_size == 4
+        assert p.timeout == 30
+        assert p.max_idle == 10 * 60
+        assert p.max_lifetime == 60 * 60
+        assert p.num_workers == 3
+
+
+@pytest.mark.parametrize("min_size, max_size", [(2, None), (0, 2), (2, 4)])
+async def test_min_size_max_size(dsn, min_size, max_size):
+    async with pool.AsyncConnectionPool(dsn, min_size=min_size, max_size=max_size) as p:
+        assert p.min_size == min_size
+        assert p.max_size == max_size if max_size is not None else min_size
+
+
+@pytest.mark.parametrize("min_size, max_size", [(0, 0), (0, None), (-1, None), (4, 2)])
+async def test_bad_size(dsn, min_size, max_size):
+    with pytest.raises(ValueError):
+        pool.AsyncConnectionPool(min_size=min_size, max_size=max_size)
+
+
+async def test_connection_class(dsn):
+    class MyConn(psycopg.AsyncConnection[Any]):
+        pass
+
+    async with pool.AsyncConnectionPool(dsn, connection_class=MyConn, min_size=1) as p:
+        async with p.connection() as conn:
+            assert isinstance(conn, MyConn)
+
+
+async def test_kwargs(dsn):
+    async with pool.AsyncConnectionPool(
+        dsn, kwargs={"autocommit": True}, min_size=1
+    ) as p:
+        async with p.connection() as conn:
+            assert conn.autocommit
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_its_really_a_pool(dsn):
+    async with pool.AsyncConnectionPool(dsn, min_size=2) as p:
+        async with p.connection() as conn:
+            pid1 = conn.info.backend_pid
+
+            async with p.connection() as conn2:
+                pid2 = conn2.info.backend_pid
+
+        async with p.connection() as conn:
+            assert conn.info.backend_pid in (pid1, pid2)
+
+
+async def test_context(dsn):
+    async with pool.AsyncConnectionPool(dsn, min_size=1) as p:
+        assert not p.closed
+    assert p.closed
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_connection_not_lost(dsn):
+    async with pool.AsyncConnectionPool(dsn, min_size=1) as p:
+        with pytest.raises(ZeroDivisionError):
+            async with p.connection() as conn:
+                pid = conn.info.backend_pid
+                1 / 0
+
+        async with p.connection() as conn2:
+            assert conn2.info.backend_pid == pid
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+async def test_concurrent_filling(dsn, monkeypatch):
+    delay_connection(monkeypatch, 0.1)
+
+    async def add_time(self, conn):
+        times.append(time() - t0)
+        await add_orig(self, conn)
+
+    add_orig = pool.AsyncConnectionPool._add_to_pool
+    monkeypatch.setattr(pool.AsyncConnectionPool, "_add_to_pool", add_time)
+
+    times: List[float] = []
+    t0 = time()
+
+    async with pool.AsyncConnectionPool(dsn, min_size=5, num_workers=2) as p:
+        await p.wait(1.0)
+        want_times = [0.1, 0.1, 0.2, 0.2, 0.3]
+        assert len(times) == len(want_times)
+        for got, want in zip(times, want_times):
+            assert got == pytest.approx(want, 0.1), times
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+async def test_wait_ready(dsn, monkeypatch):
+    delay_connection(monkeypatch, 0.1)
+    with pytest.raises(pool.PoolTimeout):
+        async with pool.AsyncConnectionPool(dsn, min_size=4, num_workers=1) as p:
+            await p.wait(0.3)
+
+    async with pool.AsyncConnectionPool(dsn, min_size=4, num_workers=1) as p:
+        await p.wait(0.5)
+
+    async with pool.AsyncConnectionPool(dsn, min_size=4, num_workers=2) as p:
+        await p.wait(0.3)
+        await p.wait(0.0001)  # idempotent
+
+
+async def test_wait_closed(dsn):
+    async with pool.AsyncConnectionPool(dsn) as p:
+        pass
+
+    with pytest.raises(pool.PoolClosed):
+        await p.wait()
+
+
+@pytest.mark.slow
+async def test_setup_no_timeout(dsn, proxy):
+    with pytest.raises(pool.PoolTimeout):
+        async with pool.AsyncConnectionPool(
+            proxy.client_dsn, min_size=1, num_workers=1
+        ) as p:
+            await p.wait(0.2)
+
+    async with pool.AsyncConnectionPool(
+        proxy.client_dsn, min_size=1, num_workers=1
+    ) as p:
+        await asyncio.sleep(0.5)
+        assert not p._pool
+        proxy.start()
+
+        async with p.connection() as conn:
+            await conn.execute("select 1")
+
+
+async def test_configure(dsn):
+    inits = 0
+
+    async def configure(conn):
+        nonlocal inits
+        inits += 1
+        async with conn.transaction():
+            await conn.execute("set default_transaction_read_only to on")
+
+    async with pool.AsyncConnectionPool(dsn, min_size=1, configure=configure) as p:
+        await p.wait(timeout=1.0)
+        async with p.connection() as conn:
+            assert inits == 1
+            res = await conn.execute("show default_transaction_read_only")
+            assert (await res.fetchone())[0] == "on"  # type: ignore[index]
+
+        async with p.connection() as conn:
+            assert inits == 1
+            res = await conn.execute("show default_transaction_read_only")
+            assert (await res.fetchone())[0] == "on"  # type: ignore[index]
+            await conn.close()
+
+        async with p.connection() as conn:
+            assert inits == 2
+            res = await conn.execute("show default_transaction_read_only")
+            assert (await res.fetchone())[0] == "on"  # type: ignore[index]
+
+
+@pytest.mark.slow
+async def test_configure_badstate(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    async def configure(conn):
+        await conn.execute("select 1")
+
+    async with pool.AsyncConnectionPool(dsn, min_size=1, configure=configure) as p:
+        with pytest.raises(pool.PoolTimeout):
+            await p.wait(timeout=0.5)
+
+    assert caplog.records
+    assert "INTRANS" in caplog.records[0].message
+
+
+@pytest.mark.slow
+async def test_configure_broken(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    async def configure(conn):
+        async with conn.transaction():
+            await conn.execute("WAT")
+
+    async with pool.AsyncConnectionPool(dsn, min_size=1, configure=configure) as p:
+        with pytest.raises(pool.PoolTimeout):
+            await p.wait(timeout=0.5)
+
+    assert caplog.records
+    assert "WAT" in caplog.records[0].message
+
+
+async def test_reset(dsn):
+    resets = 0
+
+    async def setup(conn):
+        async with conn.transaction():
+            await conn.execute("set timezone to '+1:00'")
+
+    async def reset(conn):
+        nonlocal resets
+        resets += 1
+        async with conn.transaction():
+            await conn.execute("set timezone to utc")
+
+    async with pool.AsyncConnectionPool(dsn, min_size=1, reset=reset) as p:
+        async with p.connection() as conn:
+            assert resets == 0
+            await conn.execute("set timezone to '+2:00'")
+
+        await p.wait()
+        assert resets == 1
+
+        async with p.connection() as conn:
+            cur = await conn.execute("show timezone")
+            assert (await cur.fetchone()) == ("UTC",)
+
+        await p.wait()
+        assert resets == 2
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_reset_badstate(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    async def reset(conn):
+        await conn.execute("reset all")
+
+    async with pool.AsyncConnectionPool(dsn, min_size=1, reset=reset) as p:
+        async with p.connection() as conn:
+            await conn.execute("select 1")
+            pid1 = conn.info.backend_pid
+
+        async with p.connection() as conn:
+            await conn.execute("select 1")
+            pid2 = conn.info.backend_pid
+
+    assert pid1 != pid2
+    assert caplog.records
+    assert "INTRANS" in caplog.records[0].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_reset_broken(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    async def reset(conn):
+        async with conn.transaction():
+            await conn.execute("WAT")
+
+    async with pool.AsyncConnectionPool(dsn, min_size=1, reset=reset) as p:
+        async with p.connection() as conn:
+            await conn.execute("select 1")
+            pid1 = conn.info.backend_pid
+
+        async with p.connection() as conn:
+            await conn.execute("select 1")
+            pid2 = conn.info.backend_pid
+
+    assert pid1 != pid2
+    assert caplog.records
+    assert "WAT" in caplog.records[0].message
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.crdb_skip("backend pid")
+async def test_queue(dsn):
+    async def worker(n):
+        t0 = time()
+        async with p.connection() as conn:
+            await conn.execute("select pg_sleep(0.2)")
+            pid = conn.info.backend_pid
+        t1 = time()
+        results.append((n, t1 - t0, pid))
+
+    results: List[Tuple[int, float, int]] = []
+    async with pool.AsyncConnectionPool(dsn, min_size=2) as p:
+        await p.wait()
+        ts = [create_task(worker(i)) for i in range(6)]
+        await asyncio.gather(*ts)
+
+    times = [item[1] for item in results]
+    want_times = [0.2, 0.2, 0.4, 0.4, 0.6, 0.6]
+    for got, want in zip(times, want_times):
+        assert got == pytest.approx(want, 0.1), times
+
+    assert len(set(r[2] for r in results)) == 2, results
+
+
+@pytest.mark.slow
+async def test_queue_size(dsn):
+    async def worker(t, ev=None):
+        try:
+            async with p.connection():
+                if ev:
+                    ev.set()
+                await asyncio.sleep(t)
+        except pool.TooManyRequests as e:
+            errors.append(e)
+        else:
+            success.append(True)
+
+    errors: List[Exception] = []
+    success: List[bool] = []
+
+    async with pool.AsyncConnectionPool(dsn, min_size=1, max_waiting=3) as p:
+        await p.wait()
+        ev = asyncio.Event()
+        create_task(worker(0.3, ev))
+        await ev.wait()
+
+        ts = [create_task(worker(0.1)) for i in range(4)]
+        await asyncio.gather(*ts)
+
+    assert len(success) == 4
+    assert len(errors) == 1
+    assert isinstance(errors[0], pool.TooManyRequests)
+    assert p.name in str(errors[0])
+    assert str(p.max_waiting) in str(errors[0])
+    assert p.get_stats()["requests_errors"] == 1
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.crdb_skip("backend pid")
+async def test_queue_timeout(dsn):
+    async def worker(n):
+        t0 = time()
+        try:
+            async with p.connection() as conn:
+                await conn.execute("select pg_sleep(0.2)")
+                pid = conn.info.backend_pid
+        except pool.PoolTimeout as e:
+            t1 = time()
+            errors.append((n, t1 - t0, e))
+        else:
+            t1 = time()
+            results.append((n, t1 - t0, pid))
+
+    results: List[Tuple[int, float, int]] = []
+    errors: List[Tuple[int, float, Exception]] = []
+
+    async with pool.AsyncConnectionPool(dsn, min_size=2, timeout=0.1) as p:
+        ts = [create_task(worker(i)) for i in range(4)]
+        await asyncio.gather(*ts)
+
+    assert len(results) == 2
+    assert len(errors) == 2
+    for e in errors:
+        assert 0.1 < e[1] < 0.15
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+async def test_dead_client(dsn):
+    async def worker(i, timeout):
+        try:
+            async with p.connection(timeout=timeout) as conn:
+                await conn.execute("select pg_sleep(0.3)")
+                results.append(i)
+        except pool.PoolTimeout:
+            if timeout > 0.2:
+                raise
+
+    async with pool.AsyncConnectionPool(dsn, min_size=2) as p:
+        results: List[int] = []
+        ts = [
+            create_task(worker(i, timeout))
+            for i, timeout in enumerate([0.4, 0.4, 0.1, 0.4, 0.4])
+        ]
+        await asyncio.gather(*ts)
+
+        await asyncio.sleep(0.2)
+        assert set(results) == set([0, 1, 3, 4])
+        assert len(p._pool) == 2  # no connection was lost
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.crdb_skip("backend pid")
+async def test_queue_timeout_override(dsn):
+    async def worker(n):
+        t0 = time()
+        timeout = 0.25 if n == 3 else None
+        try:
+            async with p.connection(timeout=timeout) as conn:
+                await conn.execute("select pg_sleep(0.2)")
+                pid = conn.info.backend_pid
+        except pool.PoolTimeout as e:
+            t1 = time()
+            errors.append((n, t1 - t0, e))
+        else:
+            t1 = time()
+            results.append((n, t1 - t0, pid))
+
+    results: List[Tuple[int, float, int]] = []
+    errors: List[Tuple[int, float, Exception]] = []
+
+    async with pool.AsyncConnectionPool(dsn, min_size=2, timeout=0.1) as p:
+        ts = [create_task(worker(i)) for i in range(4)]
+        await asyncio.gather(*ts)
+
+    assert len(results) == 3
+    assert len(errors) == 1
+    for e in errors:
+        assert 0.1 < e[1] < 0.15
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_broken_reconnect(dsn):
+    async with pool.AsyncConnectionPool(dsn, min_size=1) as p:
+        async with p.connection() as conn:
+            pid1 = conn.info.backend_pid
+            await conn.close()
+
+        async with p.connection() as conn2:
+            pid2 = conn2.info.backend_pid
+
+    assert pid1 != pid2
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_intrans_rollback(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    async with pool.AsyncConnectionPool(dsn, min_size=1) as p:
+        conn = await p.getconn()
+        pid = conn.info.backend_pid
+        await conn.execute("create table test_intrans_rollback ()")
+        assert conn.info.transaction_status == TransactionStatus.INTRANS
+        await p.putconn(conn)
+
+        async with p.connection() as conn2:
+            assert conn2.info.backend_pid == pid
+            assert conn2.info.transaction_status == TransactionStatus.IDLE
+            cur = await conn2.execute(
+                "select 1 from pg_class where relname = 'test_intrans_rollback'"
+            )
+            assert not await cur.fetchone()
+
+    assert len(caplog.records) == 1
+    assert "INTRANS" in caplog.records[0].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_inerror_rollback(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    async with pool.AsyncConnectionPool(dsn, min_size=1) as p:
+        conn = await p.getconn()
+        pid = conn.info.backend_pid
+        with pytest.raises(psycopg.ProgrammingError):
+            await conn.execute("wat")
+        assert conn.info.transaction_status == TransactionStatus.INERROR
+        await p.putconn(conn)
+
+        async with p.connection() as conn2:
+            assert conn2.info.backend_pid == pid
+            assert conn2.info.transaction_status == TransactionStatus.IDLE
+
+    assert len(caplog.records) == 1
+    assert "INERROR" in caplog.records[0].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+@pytest.mark.crdb_skip("copy")
+async def test_active_close(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    async with pool.AsyncConnectionPool(dsn, min_size=1) as p:
+        conn = await p.getconn()
+        pid = conn.info.backend_pid
+        conn.pgconn.exec_(b"copy (select * from generate_series(1, 10)) to stdout")
+        assert conn.info.transaction_status == TransactionStatus.ACTIVE
+        await p.putconn(conn)
+
+        async with p.connection() as conn2:
+            assert conn2.info.backend_pid != pid
+            assert conn2.info.transaction_status == TransactionStatus.IDLE
+
+    assert len(caplog.records) == 2
+    assert "ACTIVE" in caplog.records[0].message
+    assert "BAD" in caplog.records[1].message
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_fail_rollback_close(dsn, caplog, monkeypatch):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    async with pool.AsyncConnectionPool(dsn, min_size=1) as p:
+        conn = await p.getconn()
+
+        async def bad_rollback():
+            conn.pgconn.finish()
+            await orig_rollback()
+
+        # Make the rollback fail
+        orig_rollback = conn.rollback
+        monkeypatch.setattr(conn, "rollback", bad_rollback)
+
+        pid = conn.info.backend_pid
+        with pytest.raises(psycopg.ProgrammingError):
+            await conn.execute("wat")
+        assert conn.info.transaction_status == TransactionStatus.INERROR
+        await p.putconn(conn)
+
+        async with p.connection() as conn2:
+            assert conn2.info.backend_pid != pid
+            assert conn2.info.transaction_status == TransactionStatus.IDLE
+
+    assert len(caplog.records) == 3
+    assert "INERROR" in caplog.records[0].message
+    assert "OperationalError" in caplog.records[1].message
+    assert "BAD" in caplog.records[2].message
+
+
+async def test_close_no_tasks(dsn):
+    p = pool.AsyncConnectionPool(dsn)
+    assert p._sched_runner and not p._sched_runner.done()
+    assert p._workers
+    workers = p._workers[:]
+    for t in workers:
+        assert not t.done()
+
+    await p.close()
+    assert p._sched_runner is None
+    assert not p._workers
+    for t in workers:
+        assert t.done()
+
+
+async def test_putconn_no_pool(aconn_cls, dsn):
+    async with pool.AsyncConnectionPool(dsn, min_size=1) as p:
+        conn = await aconn_cls.connect(dsn)
+        with pytest.raises(ValueError):
+            await p.putconn(conn)
+
+    await conn.close()
+
+
+async def test_putconn_wrong_pool(dsn):
+    async with pool.AsyncConnectionPool(dsn, min_size=1) as p1:
+        async with pool.AsyncConnectionPool(dsn, min_size=1) as p2:
+            conn = await p1.getconn()
+            with pytest.raises(ValueError):
+                await p2.putconn(conn)
+
+
+async def test_closed_getconn(dsn):
+    p = pool.AsyncConnectionPool(dsn, min_size=1)
+    assert not p.closed
+    async with p.connection():
+        pass
+
+    await p.close()
+    assert p.closed
+
+    with pytest.raises(pool.PoolClosed):
+        async with p.connection():
+            pass
+
+
+async def test_closed_putconn(dsn):
+    p = pool.AsyncConnectionPool(dsn, min_size=1)
+
+    async with p.connection() as conn:
+        pass
+    assert not conn.closed
+
+    async with p.connection() as conn:
+        await p.close()
+    assert conn.closed
+
+
+async def test_closed_queue(dsn):
+    async def w1():
+        async with p.connection() as conn:
+            e1.set()  # Tell w0 that w1 got a connection
+            cur = await conn.execute("select 1")
+            assert await cur.fetchone() == (1,)
+            await e2.wait()  # Wait until w0 has tested w2
+        success.append("w1")
+
+    async def w2():
+        try:
+            async with p.connection():
+                pass  # unexpected
+        except pool.PoolClosed:
+            success.append("w2")
+
+    e1 = asyncio.Event()
+    e2 = asyncio.Event()
+
+    p = pool.AsyncConnectionPool(dsn, min_size=1)
+    await p.wait()
+    success: List[str] = []
+
+    t1 = create_task(w1())
+    # Wait until w1 has received a connection
+    await e1.wait()
+
+    t2 = create_task(w2())
+    # Wait until w2 is in the queue
+    await ensure_waiting(p)
+    await p.close()
+
+    # Wait for the workers to finish
+    e2.set()
+    await asyncio.gather(t1, t2)
+    assert len(success) == 2
+
+
+async def test_open_explicit(dsn):
+    p = pool.AsyncConnectionPool(dsn, open=False)
+    assert p.closed
+    with pytest.raises(pool.PoolClosed):
+        await p.getconn()
+
+    with pytest.raises(pool.PoolClosed, match="is not open yet"):
+        async with p.connection():
+            pass
+
+    await p.open()
+    try:
+        assert not p.closed
+
+        async with p.connection() as conn:
+            cur = await conn.execute("select 1")
+            assert await cur.fetchone() == (1,)
+
+    finally:
+        await p.close()
+
+    with pytest.raises(pool.PoolClosed, match="is already closed"):
+        await p.getconn()
+
+
+async def test_open_context(dsn):
+    p = pool.AsyncConnectionPool(dsn, open=False)
+    assert p.closed
+
+    async with p:
+        assert not p.closed
+
+        async with p.connection() as conn:
+            cur = await conn.execute("select 1")
+            assert await cur.fetchone() == (1,)
+
+    assert p.closed
+
+
+async def test_open_no_op(dsn):
+    p = pool.AsyncConnectionPool(dsn)
+    try:
+        assert not p.closed
+        await p.open()
+        assert not p.closed
+
+        async with p.connection() as conn:
+            cur = await conn.execute("select 1")
+            assert await cur.fetchone() == (1,)
+
+    finally:
+        await p.close()
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+async def test_open_wait(dsn, monkeypatch):
+    delay_connection(monkeypatch, 0.1)
+    with pytest.raises(pool.PoolTimeout):
+        p = pool.AsyncConnectionPool(dsn, min_size=4, num_workers=1, open=False)
+        try:
+            await p.open(wait=True, timeout=0.3)
+        finally:
+            await p.close()
+
+    p = pool.AsyncConnectionPool(dsn, min_size=4, num_workers=1, open=False)
+    try:
+        await p.open(wait=True, timeout=0.5)
+    finally:
+        await p.close()
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+async def test_open_as_wait(dsn, monkeypatch):
+    delay_connection(monkeypatch, 0.1)
+    with pytest.raises(pool.PoolTimeout):
+        async with pool.AsyncConnectionPool(dsn, min_size=4, num_workers=1) as p:
+            await p.open(wait=True, timeout=0.3)
+
+    async with pool.AsyncConnectionPool(dsn, min_size=4, num_workers=1) as p:
+        await p.open(wait=True, timeout=0.5)
+
+
+async def test_reopen(dsn):
+    p = pool.AsyncConnectionPool(dsn)
+    async with p.connection() as conn:
+        await conn.execute("select 1")
+    await p.close()
+    assert p._sched_runner is None
+
+    with pytest.raises(psycopg.OperationalError, match="cannot be reused"):
+        await p.open()
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.parametrize(
+    "min_size, want_times",
+    [
+        (2, [0.25, 0.25, 0.35, 0.45, 0.50, 0.50, 0.60, 0.70]),
+        (0, [0.35, 0.45, 0.55, 0.60, 0.65, 0.70, 0.80, 0.85]),
+    ],
+)
+async def test_grow(dsn, monkeypatch, min_size, want_times):
+    delay_connection(monkeypatch, 0.1)
+
+    async def worker(n):
+        t0 = time()
+        async with p.connection() as conn:
+            await conn.execute("select 1 from pg_sleep(0.25)")
+        t1 = time()
+        results.append((n, t1 - t0))
+
+    async with pool.AsyncConnectionPool(
+        dsn, min_size=min_size, max_size=4, num_workers=3
+    ) as p:
+        await p.wait(1.0)
+        ts = []
+        results: List[Tuple[int, float]] = []
+
+        ts = [create_task(worker(i)) for i in range(len(want_times))]
+        await asyncio.gather(*ts)
+
+    times = [item[1] for item in results]
+    for got, want in zip(times, want_times):
+        assert got == pytest.approx(want, 0.1), times
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+async def test_shrink(dsn, monkeypatch):
+
+    from psycopg_pool.pool_async import ShrinkPool
+
+    results: List[Tuple[int, int]] = []
+
+    async def run_hacked(self, pool):
+        n0 = pool._nconns
+        await orig_run(self, pool)
+        n1 = pool._nconns
+        results.append((n0, n1))
+
+    orig_run = ShrinkPool._run
+    monkeypatch.setattr(ShrinkPool, "_run", run_hacked)
+
+    async def worker(n):
+        async with p.connection() as conn:
+            await conn.execute("select pg_sleep(0.1)")
+
+    async with pool.AsyncConnectionPool(dsn, min_size=2, max_size=4, max_idle=0.2) as p:
+        await p.wait(5.0)
+        assert p.max_idle == 0.2
+
+        ts = [create_task(worker(i)) for i in range(4)]
+        await asyncio.gather(*ts)
+
+        await asyncio.sleep(1)
+
+    assert results == [(4, 4), (4, 3), (3, 2), (2, 2), (2, 2)]
+
+
+@pytest.mark.slow
+async def test_reconnect(proxy, caplog, monkeypatch):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+
+    assert pool.base.ConnectionAttempt.INITIAL_DELAY == 1.0
+    assert pool.base.ConnectionAttempt.DELAY_JITTER == 0.1
+    monkeypatch.setattr(pool.base.ConnectionAttempt, "INITIAL_DELAY", 0.1)
+    monkeypatch.setattr(pool.base.ConnectionAttempt, "DELAY_JITTER", 0.0)
+
+    caplog.clear()
+    proxy.start()
+    async with pool.AsyncConnectionPool(proxy.client_dsn, min_size=1) as p:
+        await p.wait(2.0)
+        proxy.stop()
+
+        with pytest.raises(psycopg.OperationalError):
+            async with p.connection() as conn:
+                await conn.execute("select 1")
+
+        await asyncio.sleep(1.0)
+        proxy.start()
+        await p.wait()
+
+        async with p.connection() as conn:
+            await conn.execute("select 1")
+
+    assert "BAD" in caplog.messages[0]
+    times = [rec.created for rec in caplog.records]
+    assert times[1] - times[0] < 0.05
+    deltas = [times[i + 1] - times[i] for i in range(1, len(times) - 1)]
+    assert len(deltas) == 3
+    want = 0.1
+    for delta in deltas:
+        assert delta == pytest.approx(want, 0.05), deltas
+        want *= 2
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+async def test_reconnect_failure(proxy):
+    proxy.start()
+
+    t1 = None
+
+    def failed(pool):
+        assert pool.name == "this-one"
+        nonlocal t1
+        t1 = time()
+
+    async with pool.AsyncConnectionPool(
+        proxy.client_dsn,
+        name="this-one",
+        min_size=1,
+        reconnect_timeout=1.0,
+        reconnect_failed=failed,
+    ) as p:
+        await p.wait(2.0)
+        proxy.stop()
+
+        with pytest.raises(psycopg.OperationalError):
+            async with p.connection() as conn:
+                await conn.execute("select 1")
+
+        t0 = time()
+        await asyncio.sleep(1.5)
+        assert t1
+        assert t1 - t0 == pytest.approx(1.0, 0.1)
+        assert p._nconns == 0
+
+        proxy.start()
+        t0 = time()
+        async with p.connection() as conn:
+            await conn.execute("select 1")
+        t1 = time()
+        assert t1 - t0 < 0.2
+
+
+@pytest.mark.slow
+async def test_reconnect_after_grow_failed(proxy):
+    # Retry reconnection after a failed connection attempt has put the pool
+    # in grow mode. See issue #370.
+    proxy.stop()
+
+    ev = asyncio.Event()
+
+    def failed(pool):
+        ev.set()
+
+    async with pool.AsyncConnectionPool(
+        proxy.client_dsn, min_size=4, reconnect_timeout=1.0, reconnect_failed=failed
+    ) as p:
+        await asyncio.wait_for(ev.wait(), 2.0)
+
+        with pytest.raises(pool.PoolTimeout):
+            async with p.connection(timeout=0.5) as conn:
+                pass
+
+        ev.clear()
+        await asyncio.wait_for(ev.wait(), 2.0)
+
+        proxy.start()
+
+        async with p.connection(timeout=2) as conn:
+            await conn.execute("select 1")
+
+        await p.wait(timeout=3.0)
+        assert len(p._pool) == p.min_size == 4
+
+
+@pytest.mark.slow
+async def test_refill_on_check(proxy):
+    proxy.start()
+    ev = asyncio.Event()
+
+    def failed(pool):
+        ev.set()
+
+    async with pool.AsyncConnectionPool(
+        proxy.client_dsn, min_size=4, reconnect_timeout=1.0, reconnect_failed=failed
+    ) as p:
+        # The pool is full
+        await p.wait(timeout=2)
+
+        # Break all the connection
+        proxy.stop()
+
+        # Checking the pool will empty it
+        await p.check()
+        await asyncio.wait_for(ev.wait(), 2.0)
+        assert len(p._pool) == 0
+
+        # Allow to connect again
+        proxy.start()
+
+        # Make sure that check has refilled the pool
+        await p.check()
+        await p.wait(timeout=2)
+        assert len(p._pool) == 4
+
+
+@pytest.mark.slow
+async def test_uniform_use(dsn):
+    async with pool.AsyncConnectionPool(dsn, min_size=4) as p:
+        counts = Counter[int]()
+        for i in range(8):
+            async with p.connection() as conn:
+                await asyncio.sleep(0.1)
+                counts[id(conn)] += 1
+
+    assert len(counts) == 4
+    assert set(counts.values()) == set([2])
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+async def test_resize(dsn):
+    async def sampler():
+        await asyncio.sleep(0.05)  # ensure sampling happens after shrink check
+        while True:
+            await asyncio.sleep(0.2)
+            if p.closed:
+                break
+            size.append(len(p._pool))
+
+    async def client(t):
+        async with p.connection() as conn:
+            await conn.execute("select pg_sleep(%s)", [t])
+
+    size: List[int] = []
+
+    async with pool.AsyncConnectionPool(dsn, min_size=2, max_idle=0.2) as p:
+        s = create_task(sampler())
+
+        await asyncio.sleep(0.3)
+
+        c = create_task(client(0.4))
+
+        await asyncio.sleep(0.2)
+        await p.resize(4)
+        assert p.min_size == 4
+        assert p.max_size == 4
+
+        await asyncio.sleep(0.4)
+        await p.resize(2)
+        assert p.min_size == 2
+        assert p.max_size == 2
+
+        await asyncio.sleep(0.6)
+
+    await asyncio.gather(s, c)
+    assert size == [2, 1, 3, 4, 3, 2, 2]
+
+
+@pytest.mark.parametrize("min_size, max_size", [(0, 0), (-1, None), (4, 2)])
+async def test_bad_resize(dsn, min_size, max_size):
+    async with pool.AsyncConnectionPool() as p:
+        with pytest.raises(ValueError):
+            await p.resize(min_size=min_size, max_size=max_size)
+
+
+async def test_jitter():
+    rnds = [pool.AsyncConnectionPool._jitter(30, -0.1, +0.2) for i in range(100)]
+    assert 27 <= min(rnds) <= 28
+    assert 35 < max(rnds) < 36
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+@pytest.mark.crdb_skip("backend pid")
+async def test_max_lifetime(dsn):
+    async with pool.AsyncConnectionPool(dsn, min_size=1, max_lifetime=0.2) as p:
+        await asyncio.sleep(0.1)
+        pids = []
+        for i in range(5):
+            async with p.connection() as conn:
+                pids.append(conn.info.backend_pid)
+            await asyncio.sleep(0.2)
+
+    assert pids[0] == pids[1] != pids[4], pids
+
+
+@pytest.mark.crdb_skip("backend pid")
+async def test_check(dsn, caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg.pool")
+    async with pool.AsyncConnectionPool(dsn, min_size=4) as p:
+        await p.wait(1.0)
+        async with p.connection() as conn:
+            pid = conn.info.backend_pid
+
+        await p.wait(1.0)
+        pids = set(conn.info.backend_pid for conn in p._pool)
+        assert pid in pids
+        await conn.close()
+
+        assert len(caplog.records) == 0
+        await p.check()
+        assert len(caplog.records) == 1
+        await p.wait(1.0)
+        pids2 = set(conn.info.backend_pid for conn in p._pool)
+        assert len(pids & pids2) == 3
+        assert pid not in pids2
+
+
+async def test_check_idle(dsn):
+    async with pool.AsyncConnectionPool(dsn, min_size=2) as p:
+        await p.wait(1.0)
+        await p.check()
+        async with p.connection() as conn:
+            assert conn.info.transaction_status == TransactionStatus.IDLE
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+async def test_stats_measures(dsn):
+    async def worker(n):
+        async with p.connection() as conn:
+            await conn.execute("select pg_sleep(0.2)")
+
+    async with pool.AsyncConnectionPool(dsn, min_size=2, max_size=4) as p:
+        await p.wait(2.0)
+
+        stats = p.get_stats()
+        assert stats["pool_min"] == 2
+        assert stats["pool_max"] == 4
+        assert stats["pool_size"] == 2
+        assert stats["pool_available"] == 2
+        assert stats["requests_waiting"] == 0
+
+        ts = [create_task(worker(i)) for i in range(3)]
+        await asyncio.sleep(0.1)
+        stats = p.get_stats()
+        await asyncio.gather(*ts)
+        assert stats["pool_min"] == 2
+        assert stats["pool_max"] == 4
+        assert stats["pool_size"] == 3
+        assert stats["pool_available"] == 0
+        assert stats["requests_waiting"] == 0
+
+        await p.wait(2.0)
+        ts = [create_task(worker(i)) for i in range(7)]
+        await asyncio.sleep(0.1)
+        stats = p.get_stats()
+        await asyncio.gather(*ts)
+        assert stats["pool_min"] == 2
+        assert stats["pool_max"] == 4
+        assert stats["pool_size"] == 4
+        assert stats["pool_available"] == 0
+        assert stats["requests_waiting"] == 3
+
+
+@pytest.mark.slow
+@pytest.mark.timing
+async def test_stats_usage(dsn):
+    async def worker(n):
+        try:
+            async with p.connection(timeout=0.3) as conn:
+                await conn.execute("select pg_sleep(0.2)")
+        except pool.PoolTimeout:
+            pass
+
+    async with pool.AsyncConnectionPool(dsn, min_size=3) as p:
+        await p.wait(2.0)
+
+        ts = [create_task(worker(i)) for i in range(7)]
+        await asyncio.gather(*ts)
+        stats = p.get_stats()
+        assert stats["requests_num"] == 7
+        assert stats["requests_queued"] == 4
+        assert 850 <= stats["requests_wait_ms"] <= 950
+        assert stats["requests_errors"] == 1
+        assert 1150 <= stats["usage_ms"] <= 1250
+        assert stats.get("returns_bad", 0) == 0
+
+        async with p.connection() as conn:
+            await conn.close()
+        await p.wait()
+        stats = p.pop_stats()
+        assert stats["requests_num"] == 8
+        assert stats["returns_bad"] == 1
+        async with p.connection():
+            pass
+        assert p.get_stats()["requests_num"] == 1
+
+
+@pytest.mark.slow
+async def test_stats_connect(dsn, proxy, monkeypatch):
+    proxy.start()
+    delay_connection(monkeypatch, 0.2)
+    async with pool.AsyncConnectionPool(proxy.client_dsn, min_size=3) as p:
+        await p.wait()
+        stats = p.get_stats()
+        assert stats["connections_num"] == 3
+        assert stats.get("connections_errors", 0) == 0
+        assert stats.get("connections_lost", 0) == 0
+        assert 580 <= stats["connections_ms"] < 1200
+
+        proxy.stop()
+        await p.check()
+        await asyncio.sleep(0.1)
+        stats = p.get_stats()
+        assert stats["connections_num"] > 3
+        assert stats["connections_errors"] > 0
+        assert stats["connections_lost"] == 3
+
+
+@pytest.mark.slow
+async def test_spike(dsn, monkeypatch):
+    # Inspired to https://github.com/brettwooldridge/HikariCP/blob/dev/
+    # documents/Welcome-To-The-Jungle.md
+    delay_connection(monkeypatch, 0.15)
+
+    async def worker():
+        async with p.connection():
+            await asyncio.sleep(0.002)
+
+    async with pool.AsyncConnectionPool(dsn, min_size=5, max_size=10) as p:
+        await p.wait()
+
+        ts = [create_task(worker()) for i in range(50)]
+        await asyncio.gather(*ts)
+        await p.wait()
+
+        assert len(p._pool) < 7
+
+
+async def test_debug_deadlock(dsn):
+    # https://github.com/psycopg/psycopg/issues/230
+    logger = logging.getLogger("psycopg")
+    handler = logging.StreamHandler()
+    old_level = logger.level
+    logger.setLevel(logging.DEBUG)
+    handler.setLevel(logging.DEBUG)
+    logger.addHandler(handler)
+    try:
+        async with pool.AsyncConnectionPool(dsn, min_size=4, open=True) as p:
+            await p.wait(timeout=2)
+    finally:
+        logger.removeHandler(handler)
+        logger.setLevel(old_level)
+
+
+def delay_connection(monkeypatch, sec):
+    """
+    Return a _connect_gen function delayed by the amount of seconds
+    """
+
+    async def connect_delay(*args, **kwargs):
+        t0 = time()
+        rv = await connect_orig(*args, **kwargs)
+        t1 = time()
+        await asyncio.sleep(max(0, sec - (t1 - t0)))
+        return rv
+
+    connect_orig = psycopg.AsyncConnection.connect
+    monkeypatch.setattr(psycopg.AsyncConnection, "connect", connect_delay)
+
+
+async def ensure_waiting(p, num=1):
+    while len(p._waiting) < num:
+        await asyncio.sleep(0)
diff --git a/tests/pool/test_pool_async_noasyncio.py b/tests/pool/test_pool_async_noasyncio.py
new file mode 100644
index 0000000..f6e34e4
--- /dev/null
+++ b/tests/pool/test_pool_async_noasyncio.py
@@ -0,0 +1,78 @@
+# These tests relate to AsyncConnectionPool, but are not marked asyncio
+# because they rely on the pool initialization outside the asyncio loop.
+
+import asyncio
+
+import pytest
+
+from ..utils import gc_collect
+
+try:
+    import psycopg_pool as pool
+except ImportError:
+    # Tests should have been skipped if the package is not available
+    pass
+
+
+@pytest.mark.slow
+def test_reconnect_after_max_lifetime(dsn, asyncio_run):
+    # See issue #219, pool created before the loop.
+    p = pool.AsyncConnectionPool(dsn, min_size=1, max_lifetime=0.2, open=False)
+
+    async def test():
+        try:
+            await p.open()
+            ns = []
+            for i in range(5):
+                async with p.connection() as conn:
+                    cur = await conn.execute("select 1")
+                    ns.append(await cur.fetchone())
+                await asyncio.sleep(0.2)
+            assert len(ns) == 5
+        finally:
+            await p.close()
+
+    asyncio_run(asyncio.wait_for(test(), timeout=2.0))
+
+
+@pytest.mark.slow
+def test_working_created_before_loop(dsn, asyncio_run):
+    p = pool.AsyncNullConnectionPool(dsn, open=False)
+
+    async def test():
+        try:
+            await p.open()
+            ns = []
+            for i in range(5):
+                async with p.connection() as conn:
+                    cur = await conn.execute("select 1")
+                    ns.append(await cur.fetchone())
+                await asyncio.sleep(0.2)
+            assert len(ns) == 5
+        finally:
+            await p.close()
+
+    asyncio_run(asyncio.wait_for(test(), timeout=2.0))
+
+
+def test_cant_create_open_outside_loop(dsn):
+    with pytest.raises(RuntimeError):
+        pool.AsyncConnectionPool(dsn, open=True)
+
+
+@pytest.fixture
+def asyncio_run(recwarn):
+    """Fixture reuturning asyncio.run, but managing resources at exit.
+
+    In certain runs, fd objects are leaked and the error will only be caught
+    downstream, by some innocent test calling gc_collect().
+    """
+    recwarn.clear()
+    try:
+        yield asyncio.run
+    finally:
+        gc_collect()
+        if recwarn:
+            warn = recwarn.pop(ResourceWarning)
+            assert "unclosed event loop" in str(warn.message)
+            assert not recwarn
diff --git a/tests/pool/test_sched.py b/tests/pool/test_sched.py
new file mode 100644
index 0000000..b3d2572
--- /dev/null
+++ b/tests/pool/test_sched.py
@@ -0,0 +1,154 @@
+import logging
+from time import time, sleep
+from functools import partial
+from threading import Thread
+
+import pytest
+
+try:
+    from psycopg_pool.sched import Scheduler
+except ImportError:
+    # Tests should have been skipped if the package is not available
+    pass
+
+pytestmark = [pytest.mark.timing]
+
+
+@pytest.mark.slow
+def test_sched():
+    s = Scheduler()
+    results = []
+
+    def worker(i):
+        results.append((i, time()))
+
+    t0 = time()
+    s.enter(0.1, partial(worker, 1))
+    s.enter(0.4, partial(worker, 3))
+    s.enter(0.3, None)
+    s.enter(0.2, partial(worker, 2))
+    s.run()
+    assert len(results) == 2
+    assert results[0][0] == 1
+    assert results[0][1] - t0 == pytest.approx(0.1, 0.1)
+    assert results[1][0] == 2
+    assert results[1][1] - t0 == pytest.approx(0.2, 0.1)
+
+
+@pytest.mark.slow
+def test_sched_thread():
+    s = Scheduler()
+    t = Thread(target=s.run, daemon=True)
+    t.start()
+
+    results = []
+
+    def worker(i):
+        results.append((i, time()))
+
+    t0 = time()
+    s.enter(0.1, partial(worker, 1))
+    s.enter(0.4, partial(worker, 3))
+    s.enter(0.3, None)
+    s.enter(0.2, partial(worker, 2))
+
+    t.join()
+    t1 = time()
+    assert t1 - t0 == pytest.approx(0.3, 0.2)
+
+    assert len(results) == 2
+    assert results[0][0] == 1
+    assert results[0][1] - t0 == pytest.approx(0.1, 0.2)
+    assert results[1][0] == 2
+    assert results[1][1] - t0 == pytest.approx(0.2, 0.2)
+
+
+@pytest.mark.slow
+def test_sched_error(caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg")
+    s = Scheduler()
+    t = Thread(target=s.run, daemon=True)
+    t.start()
+
+    results = []
+
+    def worker(i):
+        results.append((i, time()))
+
+    def error():
+        1 / 0
+
+    t0 = time()
+    s.enter(0.1, partial(worker, 1))
+    s.enter(0.4, None)
+    s.enter(0.3, partial(worker, 2))
+    s.enter(0.2, error)
+
+    t.join()
+    t1 = time()
+    assert t1 - t0 == pytest.approx(0.4, 0.1)
+
+    assert len(results) == 2
+    assert results[0][0] == 1
+    assert results[0][1] - t0 == pytest.approx(0.1, 0.1)
+    assert results[1][0] == 2
+    assert results[1][1] - t0 == pytest.approx(0.3, 0.1)
+
+    assert len(caplog.records) == 1
+    assert "ZeroDivisionError" in caplog.records[0].message
+
+
+@pytest.mark.slow
+def test_empty_queue_timeout():
+    s = Scheduler()
+
+    t0 = time()
+    times = []
+
+    wait_orig = s._event.wait
+
+    def wait_logging(timeout=None):
+        rv = wait_orig(timeout)
+        times.append(time() - t0)
+        return rv
+
+    setattr(s._event, "wait", wait_logging)
+    s.EMPTY_QUEUE_TIMEOUT = 0.2
+
+    t = Thread(target=s.run)
+    t.start()
+    sleep(0.5)
+    s.enter(0.5, None)
+    t.join()
+    times.append(time() - t0)
+    for got, want in zip(times, [0.2, 0.4, 0.5, 1.0]):
+        assert got == pytest.approx(want, 0.2), times
+
+
+@pytest.mark.slow
+def test_first_task_rescheduling():
+    s = Scheduler()
+
+    t0 = time()
+    times = []
+
+    wait_orig = s._event.wait
+
+    def wait_logging(timeout=None):
+        rv = wait_orig(timeout)
+        times.append(time() - t0)
+        return rv
+
+    setattr(s._event, "wait", wait_logging)
+    s.EMPTY_QUEUE_TIMEOUT = 0.1
+
+    s.enter(0.4, lambda: None)
+    t = Thread(target=s.run)
+    t.start()
+    s.enter(0.6, None)  # this task doesn't trigger a reschedule
+    sleep(0.1)
+    s.enter(0.1, lambda: None)  # this triggers a reschedule
+    t.join()
+    times.append(time() - t0)
+    for got, want in zip(times, [0.1, 0.2, 0.4, 0.6, 0.6]):
+        assert got == pytest.approx(want, 0.2), times
diff --git a/tests/pool/test_sched_async.py b/tests/pool/test_sched_async.py
new file mode 100644
index 0000000..492d620
--- /dev/null
+++ b/tests/pool/test_sched_async.py
@@ -0,0 +1,159 @@
+import asyncio
+import logging
+from time import time
+from functools import partial
+
+import pytest
+
+from psycopg._compat import create_task
+
+try:
+    from psycopg_pool.sched import AsyncScheduler
+except ImportError:
+    # Tests should have been skipped if the package is not available
+    pass
+
+pytestmark = [pytest.mark.asyncio, pytest.mark.timing]
+
+
+@pytest.mark.slow
+async def test_sched():
+    s = AsyncScheduler()
+    results = []
+
+    async def worker(i):
+        results.append((i, time()))
+
+    t0 = time()
+    await s.enter(0.1, partial(worker, 1))
+    await s.enter(0.4, partial(worker, 3))
+    await s.enter(0.3, None)
+    await s.enter(0.2, partial(worker, 2))
+    await s.run()
+    assert len(results) == 2
+    assert results[0][0] == 1
+    assert results[0][1] - t0 == pytest.approx(0.1, 0.1)
+    assert results[1][0] == 2
+    assert results[1][1] - t0 == pytest.approx(0.2, 0.1)
+
+
+@pytest.mark.slow
+async def test_sched_task():
+    s = AsyncScheduler()
+    t = create_task(s.run())
+
+    results = []
+
+    async def worker(i):
+        results.append((i, time()))
+
+    t0 = time()
+    await s.enter(0.1, partial(worker, 1))
+    await s.enter(0.4, partial(worker, 3))
+    await s.enter(0.3, None)
+    await s.enter(0.2, partial(worker, 2))
+
+    await asyncio.gather(t)
+    t1 = time()
+    assert t1 - t0 == pytest.approx(0.3, 0.2)
+
+    assert len(results) == 2
+    assert results[0][0] == 1
+    assert results[0][1] - t0 == pytest.approx(0.1, 0.2)
+    assert results[1][0] == 2
+    assert results[1][1] - t0 == pytest.approx(0.2, 0.2)
+
+
+@pytest.mark.slow
+async def test_sched_error(caplog):
+    caplog.set_level(logging.WARNING, logger="psycopg")
+    s = AsyncScheduler()
+    t = create_task(s.run())
+
+    results = []
+
+    async def worker(i):
+        results.append((i, time()))
+
+    async def error():
+        1 / 0
+
+    t0 = time()
+    await s.enter(0.1, partial(worker, 1))
+    await s.enter(0.4, None)
+    await s.enter(0.3, partial(worker, 2))
+    await s.enter(0.2, error)
+
+    await asyncio.gather(t)
+    t1 = time()
+    assert t1 - t0 == pytest.approx(0.4, 0.1)
+
+    assert len(results) == 2
+    assert results[0][0] == 1
+    assert results[0][1] - t0 == pytest.approx(0.1, 0.1)
+    assert results[1][0] == 2
+    assert results[1][1] - t0 == pytest.approx(0.3, 0.1)
+
+    assert len(caplog.records) == 1
+    assert "ZeroDivisionError" in caplog.records[0].message
+
+
+@pytest.mark.slow
+async def test_empty_queue_timeout():
+    s = AsyncScheduler()
+
+    t0 = time()
+    times = []
+
+    wait_orig = s._event.wait
+
+    async def wait_logging():
+        try:
+            rv = await wait_orig()
+        finally:
+            times.append(time() - t0)
+        return rv
+
+    setattr(s._event, "wait", wait_logging)
+    s.EMPTY_QUEUE_TIMEOUT = 0.2
+
+    t = create_task(s.run())
+    await asyncio.sleep(0.5)
+    await s.enter(0.5, None)
+    await asyncio.gather(t)
+    times.append(time() - t0)
+    for got, want in zip(times, [0.2, 0.4, 0.5, 1.0]):
+        assert got == pytest.approx(want, 0.2), times
+
+
+@pytest.mark.slow
+async def test_first_task_rescheduling():
+    s = AsyncScheduler()
+
+    t0 = time()
+    times = []
+
+    wait_orig = s._event.wait
+
+    async def wait_logging():
+        try:
+            rv = await wait_orig()
+        finally:
+            times.append(time() - t0)
+        return rv
+
+    setattr(s._event, "wait", wait_logging)
+    s.EMPTY_QUEUE_TIMEOUT = 0.1
+
+    async def noop():
+        pass
+
+    await s.enter(0.4, noop)
+    t = create_task(s.run())
+    await s.enter(0.6, None)  # this task doesn't trigger a reschedule
+    await asyncio.sleep(0.1)
+    await s.enter(0.1, noop)  # this triggers a reschedule
+    await asyncio.gather(t)
+    times.append(time() - t0)
+    for got, want in zip(times, [0.1, 0.2, 0.4, 0.6, 0.6]):
+        assert got == pytest.approx(want, 0.2), times