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-rw-r--r--src/time/sleep_test.go821
1 files changed, 821 insertions, 0 deletions
diff --git a/src/time/sleep_test.go b/src/time/sleep_test.go
new file mode 100644
index 0000000..5a949b6
--- /dev/null
+++ b/src/time/sleep_test.go
@@ -0,0 +1,821 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package time_test
+
+import (
+ "errors"
+ "fmt"
+ "internal/testenv"
+ "math/rand"
+ "runtime"
+ "strings"
+ "sync"
+ "sync/atomic"
+ "testing"
+ . "time"
+)
+
+// Go runtime uses different Windows timers for time.Now and sleeping.
+// These can tick at different frequencies and can arrive out of sync.
+// The effect can be seen, for example, as time.Sleep(100ms) is actually
+// shorter then 100ms when measured as difference between time.Now before and
+// after time.Sleep call. This was observed on Windows XP SP3 (windows/386).
+// windowsInaccuracy is to ignore such errors.
+const windowsInaccuracy = 17 * Millisecond
+
+func TestSleep(t *testing.T) {
+ const delay = 100 * Millisecond
+ go func() {
+ Sleep(delay / 2)
+ Interrupt()
+ }()
+ start := Now()
+ Sleep(delay)
+ delayadj := delay
+ if runtime.GOOS == "windows" {
+ delayadj -= windowsInaccuracy
+ }
+ duration := Now().Sub(start)
+ if duration < delayadj {
+ t.Fatalf("Sleep(%s) slept for only %s", delay, duration)
+ }
+}
+
+// Test the basic function calling behavior. Correct queueing
+// behavior is tested elsewhere, since After and AfterFunc share
+// the same code.
+func TestAfterFunc(t *testing.T) {
+ i := 10
+ c := make(chan bool)
+ var f func()
+ f = func() {
+ i--
+ if i >= 0 {
+ AfterFunc(0, f)
+ Sleep(1 * Second)
+ } else {
+ c <- true
+ }
+ }
+
+ AfterFunc(0, f)
+ <-c
+}
+
+func TestAfterStress(t *testing.T) {
+ stop := uint32(0)
+ go func() {
+ for atomic.LoadUint32(&stop) == 0 {
+ runtime.GC()
+ // Yield so that the OS can wake up the timer thread,
+ // so that it can generate channel sends for the main goroutine,
+ // which will eventually set stop = 1 for us.
+ Sleep(Nanosecond)
+ }
+ }()
+ ticker := NewTicker(1)
+ for i := 0; i < 100; i++ {
+ <-ticker.C
+ }
+ ticker.Stop()
+ atomic.StoreUint32(&stop, 1)
+}
+
+func benchmark(b *testing.B, bench func(n int)) {
+
+ // Create equal number of garbage timers on each P before starting
+ // the benchmark.
+ var wg sync.WaitGroup
+ garbageAll := make([][]*Timer, runtime.GOMAXPROCS(0))
+ for i := range garbageAll {
+ wg.Add(1)
+ go func(i int) {
+ defer wg.Done()
+ garbage := make([]*Timer, 1<<15)
+ for j := range garbage {
+ garbage[j] = AfterFunc(Hour, nil)
+ }
+ garbageAll[i] = garbage
+ }(i)
+ }
+ wg.Wait()
+
+ b.ResetTimer()
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ bench(1000)
+ }
+ })
+ b.StopTimer()
+
+ for _, garbage := range garbageAll {
+ for _, t := range garbage {
+ t.Stop()
+ }
+ }
+}
+
+func BenchmarkAfterFunc(b *testing.B) {
+ benchmark(b, func(n int) {
+ c := make(chan bool)
+ var f func()
+ f = func() {
+ n--
+ if n >= 0 {
+ AfterFunc(0, f)
+ } else {
+ c <- true
+ }
+ }
+
+ AfterFunc(0, f)
+ <-c
+ })
+}
+
+func BenchmarkAfter(b *testing.B) {
+ benchmark(b, func(n int) {
+ for i := 0; i < n; i++ {
+ <-After(1)
+ }
+ })
+}
+
+func BenchmarkStop(b *testing.B) {
+ benchmark(b, func(n int) {
+ for i := 0; i < n; i++ {
+ NewTimer(1 * Second).Stop()
+ }
+ })
+}
+
+func BenchmarkSimultaneousAfterFunc(b *testing.B) {
+ benchmark(b, func(n int) {
+ var wg sync.WaitGroup
+ wg.Add(n)
+ for i := 0; i < n; i++ {
+ AfterFunc(0, wg.Done)
+ }
+ wg.Wait()
+ })
+}
+
+func BenchmarkStartStop(b *testing.B) {
+ benchmark(b, func(n int) {
+ timers := make([]*Timer, n)
+ for i := 0; i < n; i++ {
+ timers[i] = AfterFunc(Hour, nil)
+ }
+
+ for i := 0; i < n; i++ {
+ timers[i].Stop()
+ }
+ })
+}
+
+func BenchmarkReset(b *testing.B) {
+ benchmark(b, func(n int) {
+ t := NewTimer(Hour)
+ for i := 0; i < n; i++ {
+ t.Reset(Hour)
+ }
+ t.Stop()
+ })
+}
+
+func BenchmarkSleep(b *testing.B) {
+ benchmark(b, func(n int) {
+ var wg sync.WaitGroup
+ wg.Add(n)
+ for i := 0; i < n; i++ {
+ go func() {
+ Sleep(Nanosecond)
+ wg.Done()
+ }()
+ }
+ wg.Wait()
+ })
+}
+
+func TestAfter(t *testing.T) {
+ const delay = 100 * Millisecond
+ start := Now()
+ end := <-After(delay)
+ delayadj := delay
+ if runtime.GOOS == "windows" {
+ delayadj -= windowsInaccuracy
+ }
+ if duration := Now().Sub(start); duration < delayadj {
+ t.Fatalf("After(%s) slept for only %d ns", delay, duration)
+ }
+ if min := start.Add(delayadj); end.Before(min) {
+ t.Fatalf("After(%s) expect >= %s, got %s", delay, min, end)
+ }
+}
+
+func TestAfterTick(t *testing.T) {
+ const Count = 10
+ Delta := 100 * Millisecond
+ if testing.Short() {
+ Delta = 10 * Millisecond
+ }
+ t0 := Now()
+ for i := 0; i < Count; i++ {
+ <-After(Delta)
+ }
+ t1 := Now()
+ d := t1.Sub(t0)
+ target := Delta * Count
+ if d < target*9/10 {
+ t.Fatalf("%d ticks of %s too fast: took %s, expected %s", Count, Delta, d, target)
+ }
+ if !testing.Short() && d > target*30/10 {
+ t.Fatalf("%d ticks of %s too slow: took %s, expected %s", Count, Delta, d, target)
+ }
+}
+
+func TestAfterStop(t *testing.T) {
+ // We want to test that we stop a timer before it runs.
+ // We also want to test that it didn't run after a longer timer.
+ // Since we don't want the test to run for too long, we don't
+ // want to use lengthy times. That makes the test inherently flaky.
+ // So only report an error if it fails five times in a row.
+
+ var errs []string
+ logErrs := func() {
+ for _, e := range errs {
+ t.Log(e)
+ }
+ }
+
+ for i := 0; i < 5; i++ {
+ AfterFunc(100*Millisecond, func() {})
+ t0 := NewTimer(50 * Millisecond)
+ c1 := make(chan bool, 1)
+ t1 := AfterFunc(150*Millisecond, func() { c1 <- true })
+ c2 := After(200 * Millisecond)
+ if !t0.Stop() {
+ errs = append(errs, "failed to stop event 0")
+ continue
+ }
+ if !t1.Stop() {
+ errs = append(errs, "failed to stop event 1")
+ continue
+ }
+ <-c2
+ select {
+ case <-t0.C:
+ errs = append(errs, "event 0 was not stopped")
+ continue
+ case <-c1:
+ errs = append(errs, "event 1 was not stopped")
+ continue
+ default:
+ }
+ if t1.Stop() {
+ errs = append(errs, "Stop returned true twice")
+ continue
+ }
+
+ // Test passed, so all done.
+ if len(errs) > 0 {
+ t.Logf("saw %d errors, ignoring to avoid flakiness", len(errs))
+ logErrs()
+ }
+
+ return
+ }
+
+ t.Errorf("saw %d errors", len(errs))
+ logErrs()
+}
+
+func TestAfterQueuing(t *testing.T) {
+ // This test flakes out on some systems,
+ // so we'll try it a few times before declaring it a failure.
+ const attempts = 5
+ err := errors.New("!=nil")
+ for i := 0; i < attempts && err != nil; i++ {
+ delta := Duration(20+i*50) * Millisecond
+ if err = testAfterQueuing(delta); err != nil {
+ t.Logf("attempt %v failed: %v", i, err)
+ }
+ }
+ if err != nil {
+ t.Fatal(err)
+ }
+}
+
+var slots = []int{5, 3, 6, 6, 6, 1, 1, 2, 7, 9, 4, 8, 0}
+
+type afterResult struct {
+ slot int
+ t Time
+}
+
+func await(slot int, result chan<- afterResult, ac <-chan Time) {
+ result <- afterResult{slot, <-ac}
+}
+
+func testAfterQueuing(delta Duration) error {
+ // make the result channel buffered because we don't want
+ // to depend on channel queueing semantics that might
+ // possibly change in the future.
+ result := make(chan afterResult, len(slots))
+
+ t0 := Now()
+ for _, slot := range slots {
+ go await(slot, result, After(Duration(slot)*delta))
+ }
+ var order []int
+ var times []Time
+ for range slots {
+ r := <-result
+ order = append(order, r.slot)
+ times = append(times, r.t)
+ }
+ for i := range order {
+ if i > 0 && order[i] < order[i-1] {
+ return fmt.Errorf("After calls returned out of order: %v", order)
+ }
+ }
+ for i, t := range times {
+ dt := t.Sub(t0)
+ target := Duration(order[i]) * delta
+ if dt < target-delta/2 || dt > target+delta*10 {
+ return fmt.Errorf("After(%s) arrived at %s, expected [%s,%s]", target, dt, target-delta/2, target+delta*10)
+ }
+ }
+ return nil
+}
+
+func TestTimerStopStress(t *testing.T) {
+ if testing.Short() {
+ return
+ }
+ for i := 0; i < 100; i++ {
+ go func(i int) {
+ timer := AfterFunc(2*Second, func() {
+ t.Errorf("timer %d was not stopped", i)
+ })
+ Sleep(1 * Second)
+ timer.Stop()
+ }(i)
+ }
+ Sleep(3 * Second)
+}
+
+func TestSleepZeroDeadlock(t *testing.T) {
+ // Sleep(0) used to hang, the sequence of events was as follows.
+ // Sleep(0) sets G's status to Gwaiting, but then immediately returns leaving the status.
+ // Then the goroutine calls e.g. new and falls down into the scheduler due to pending GC.
+ // After the GC nobody wakes up the goroutine from Gwaiting status.
+ defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(4))
+ c := make(chan bool)
+ go func() {
+ for i := 0; i < 100; i++ {
+ runtime.GC()
+ }
+ c <- true
+ }()
+ for i := 0; i < 100; i++ {
+ Sleep(0)
+ tmp := make(chan bool, 1)
+ tmp <- true
+ <-tmp
+ }
+ <-c
+}
+
+func testReset(d Duration) error {
+ t0 := NewTimer(2 * d)
+ Sleep(d)
+ if !t0.Reset(3 * d) {
+ return errors.New("resetting unfired timer returned false")
+ }
+ Sleep(2 * d)
+ select {
+ case <-t0.C:
+ return errors.New("timer fired early")
+ default:
+ }
+ Sleep(2 * d)
+ select {
+ case <-t0.C:
+ default:
+ return errors.New("reset timer did not fire")
+ }
+
+ if t0.Reset(50 * Millisecond) {
+ return errors.New("resetting expired timer returned true")
+ }
+ return nil
+}
+
+func TestReset(t *testing.T) {
+ // We try to run this test with increasingly larger multiples
+ // until one works so slow, loaded hardware isn't as flaky,
+ // but without slowing down fast machines unnecessarily.
+ const unit = 25 * Millisecond
+ tries := []Duration{
+ 1 * unit,
+ 3 * unit,
+ 7 * unit,
+ 15 * unit,
+ }
+ var err error
+ for _, d := range tries {
+ err = testReset(d)
+ if err == nil {
+ t.Logf("passed using duration %v", d)
+ return
+ }
+ }
+ t.Error(err)
+}
+
+// Test that sleeping (via Sleep or Timer) for an interval so large it
+// overflows does not result in a short sleep duration. Nor does it interfere
+// with execution of other timers. If it does, timers in this or subsequent
+// tests may not fire.
+func TestOverflowSleep(t *testing.T) {
+ const big = Duration(int64(1<<63 - 1))
+
+ go func() {
+ Sleep(big)
+ // On failure, this may return after the test has completed, so
+ // we need to panic instead.
+ panic("big sleep returned")
+ }()
+
+ select {
+ case <-After(big):
+ t.Fatalf("big timeout fired")
+ case <-After(25 * Millisecond):
+ // OK
+ }
+
+ const neg = Duration(-1 << 63)
+ Sleep(neg) // Returns immediately.
+ select {
+ case <-After(neg):
+ // OK
+ case <-After(1 * Second):
+ t.Fatalf("negative timeout didn't fire")
+ }
+}
+
+// Test that a panic while deleting a timer does not leave
+// the timers mutex held, deadlocking a ticker.Stop in a defer.
+func TestIssue5745(t *testing.T) {
+ ticker := NewTicker(Hour)
+ defer func() {
+ // would deadlock here before the fix due to
+ // lock taken before the segfault.
+ ticker.Stop()
+
+ if r := recover(); r == nil {
+ t.Error("Expected panic, but none happened.")
+ }
+ }()
+
+ // cause a panic due to a segfault
+ var timer *Timer
+ timer.Stop()
+ t.Error("Should be unreachable.")
+}
+
+func TestOverflowPeriodRuntimeTimer(t *testing.T) {
+ // This may hang forever if timers are broken. See comment near
+ // the end of CheckRuntimeTimerOverflow in internal_test.go.
+ CheckRuntimeTimerPeriodOverflow()
+}
+
+func checkZeroPanicString(t *testing.T) {
+ e := recover()
+ s, _ := e.(string)
+ if want := "called on uninitialized Timer"; !strings.Contains(s, want) {
+ t.Errorf("panic = %v; want substring %q", e, want)
+ }
+}
+
+func TestZeroTimerResetPanics(t *testing.T) {
+ defer checkZeroPanicString(t)
+ var tr Timer
+ tr.Reset(1)
+}
+
+func TestZeroTimerStopPanics(t *testing.T) {
+ defer checkZeroPanicString(t)
+ var tr Timer
+ tr.Stop()
+}
+
+// Test that zero duration timers aren't missed by the scheduler. Regression test for issue 44868.
+func TestZeroTimer(t *testing.T) {
+ if testing.Short() {
+ t.Skip("-short")
+ }
+
+ for i := 0; i < 1000000; i++ {
+ s := Now()
+ ti := NewTimer(0)
+ <-ti.C
+ if diff := Since(s); diff > 2*Second {
+ t.Errorf("Expected time to get value from Timer channel in less than 2 sec, took %v", diff)
+ }
+ }
+}
+
+// Test that rapidly moving a timer earlier doesn't cause it to get dropped.
+// Issue 47329.
+func TestTimerModifiedEarlier(t *testing.T) {
+ if runtime.GOOS == "plan9" && runtime.GOARCH == "arm" {
+ testenv.SkipFlaky(t, 50470)
+ }
+
+ past := Until(Unix(0, 0))
+ count := 1000
+ fail := 0
+ for i := 0; i < count; i++ {
+ timer := NewTimer(Hour)
+ for j := 0; j < 10; j++ {
+ if !timer.Stop() {
+ <-timer.C
+ }
+ timer.Reset(past)
+ }
+
+ deadline := NewTimer(10 * Second)
+ defer deadline.Stop()
+ now := Now()
+ select {
+ case <-timer.C:
+ if since := Since(now); since > 8*Second {
+ t.Errorf("timer took too long (%v)", since)
+ fail++
+ }
+ case <-deadline.C:
+ t.Error("deadline expired")
+ }
+ }
+
+ if fail > 0 {
+ t.Errorf("%d failures", fail)
+ }
+}
+
+// Test that rapidly moving timers earlier and later doesn't cause
+// some of the sleep times to be lost.
+// Issue 47762
+func TestAdjustTimers(t *testing.T) {
+ var rnd = rand.New(rand.NewSource(Now().UnixNano()))
+
+ timers := make([]*Timer, 100)
+ states := make([]int, len(timers))
+ indices := rnd.Perm(len(timers))
+
+ for len(indices) != 0 {
+ var ii = rnd.Intn(len(indices))
+ var i = indices[ii]
+
+ var timer = timers[i]
+ var state = states[i]
+ states[i]++
+
+ switch state {
+ case 0:
+ timers[i] = NewTimer(0)
+ case 1:
+ <-timer.C // Timer is now idle.
+
+ // Reset to various long durations, which we'll cancel.
+ case 2:
+ if timer.Reset(1 * Minute) {
+ panic("shouldn't be active (1)")
+ }
+ case 4:
+ if timer.Reset(3 * Minute) {
+ panic("shouldn't be active (3)")
+ }
+ case 6:
+ if timer.Reset(2 * Minute) {
+ panic("shouldn't be active (2)")
+ }
+
+ // Stop and drain a long-duration timer.
+ case 3, 5, 7:
+ if !timer.Stop() {
+ t.Logf("timer %d state %d Stop returned false", i, state)
+ <-timer.C
+ }
+
+ // Start a short-duration timer we expect to select without blocking.
+ case 8:
+ if timer.Reset(0) {
+ t.Fatal("timer.Reset returned true")
+ }
+ case 9:
+ now := Now()
+ <-timer.C
+ dur := Since(now)
+ if dur > 750*Millisecond {
+ t.Errorf("timer %d took %v to complete", i, dur)
+ }
+
+ // Timer is done. Swap with tail and remove.
+ case 10:
+ indices[ii] = indices[len(indices)-1]
+ indices = indices[:len(indices)-1]
+ }
+ }
+}
+
+// Benchmark timer latency when the thread that creates the timer is busy with
+// other work and the timers must be serviced by other threads.
+// https://golang.org/issue/38860
+func BenchmarkParallelTimerLatency(b *testing.B) {
+ gmp := runtime.GOMAXPROCS(0)
+ if gmp < 2 || runtime.NumCPU() < gmp {
+ b.Skip("skipping with GOMAXPROCS < 2 or NumCPU < GOMAXPROCS")
+ }
+
+ // allocate memory now to avoid GC interference later.
+ timerCount := gmp - 1
+ stats := make([]struct {
+ sum float64
+ max Duration
+ count int64
+ _ [5]int64 // cache line padding
+ }, timerCount)
+
+ // Ensure the time to start new threads to service timers will not pollute
+ // the results.
+ warmupScheduler(gmp)
+
+ // Note that other than the AfterFunc calls this benchmark is measuring it
+ // avoids using any other timers. In particular, the main goroutine uses
+ // doWork to spin for some durations because up through Go 1.15 if all
+ // threads are idle sysmon could leave deep sleep when we wake.
+
+ // Ensure sysmon is in deep sleep.
+ doWork(30 * Millisecond)
+
+ b.ResetTimer()
+
+ const delay = Millisecond
+ var wg sync.WaitGroup
+ var count int32
+ for i := 0; i < b.N; i++ {
+ wg.Add(timerCount)
+ atomic.StoreInt32(&count, 0)
+ for j := 0; j < timerCount; j++ {
+ j := j
+ expectedWakeup := Now().Add(delay)
+ AfterFunc(delay, func() {
+ late := Since(expectedWakeup)
+ if late < 0 {
+ late = 0
+ }
+ stats[j].count++
+ stats[j].sum += float64(late.Nanoseconds())
+ if late > stats[j].max {
+ stats[j].max = late
+ }
+ atomic.AddInt32(&count, 1)
+ for atomic.LoadInt32(&count) < int32(timerCount) {
+ // spin until all timers fired
+ }
+ wg.Done()
+ })
+ }
+
+ for atomic.LoadInt32(&count) < int32(timerCount) {
+ // spin until all timers fired
+ }
+ wg.Wait()
+
+ // Spin for a bit to let the other scheduler threads go idle before the
+ // next round.
+ doWork(Millisecond)
+ }
+ var total float64
+ var samples float64
+ max := Duration(0)
+ for _, s := range stats {
+ if s.max > max {
+ max = s.max
+ }
+ total += s.sum
+ samples += float64(s.count)
+ }
+ b.ReportMetric(0, "ns/op")
+ b.ReportMetric(total/samples, "avg-late-ns")
+ b.ReportMetric(float64(max.Nanoseconds()), "max-late-ns")
+}
+
+// Benchmark timer latency with staggered wakeup times and varying CPU bound
+// workloads. https://golang.org/issue/38860
+func BenchmarkStaggeredTickerLatency(b *testing.B) {
+ gmp := runtime.GOMAXPROCS(0)
+ if gmp < 2 || runtime.NumCPU() < gmp {
+ b.Skip("skipping with GOMAXPROCS < 2 or NumCPU < GOMAXPROCS")
+ }
+
+ const delay = 3 * Millisecond
+
+ for _, dur := range []Duration{300 * Microsecond, 2 * Millisecond} {
+ b.Run(fmt.Sprintf("work-dur=%s", dur), func(b *testing.B) {
+ for tickersPerP := 1; tickersPerP < int(delay/dur)+1; tickersPerP++ {
+ tickerCount := gmp * tickersPerP
+ b.Run(fmt.Sprintf("tickers-per-P=%d", tickersPerP), func(b *testing.B) {
+ // allocate memory now to avoid GC interference later.
+ stats := make([]struct {
+ sum float64
+ max Duration
+ count int64
+ _ [5]int64 // cache line padding
+ }, tickerCount)
+
+ // Ensure the time to start new threads to service timers
+ // will not pollute the results.
+ warmupScheduler(gmp)
+
+ b.ResetTimer()
+
+ var wg sync.WaitGroup
+ wg.Add(tickerCount)
+ for j := 0; j < tickerCount; j++ {
+ j := j
+ doWork(delay / Duration(gmp))
+ expectedWakeup := Now().Add(delay)
+ ticker := NewTicker(delay)
+ go func(c int, ticker *Ticker, firstWake Time) {
+ defer ticker.Stop()
+
+ for ; c > 0; c-- {
+ <-ticker.C
+ late := Since(expectedWakeup)
+ if late < 0 {
+ late = 0
+ }
+ stats[j].count++
+ stats[j].sum += float64(late.Nanoseconds())
+ if late > stats[j].max {
+ stats[j].max = late
+ }
+ expectedWakeup = expectedWakeup.Add(delay)
+ doWork(dur)
+ }
+ wg.Done()
+ }(b.N, ticker, expectedWakeup)
+ }
+ wg.Wait()
+
+ var total float64
+ var samples float64
+ max := Duration(0)
+ for _, s := range stats {
+ if s.max > max {
+ max = s.max
+ }
+ total += s.sum
+ samples += float64(s.count)
+ }
+ b.ReportMetric(0, "ns/op")
+ b.ReportMetric(total/samples, "avg-late-ns")
+ b.ReportMetric(float64(max.Nanoseconds()), "max-late-ns")
+ })
+ }
+ })
+ }
+}
+
+// warmupScheduler ensures the scheduler has at least targetThreadCount threads
+// in its thread pool.
+func warmupScheduler(targetThreadCount int) {
+ var wg sync.WaitGroup
+ var count int32
+ for i := 0; i < targetThreadCount; i++ {
+ wg.Add(1)
+ go func() {
+ atomic.AddInt32(&count, 1)
+ for atomic.LoadInt32(&count) < int32(targetThreadCount) {
+ // spin until all threads started
+ }
+
+ // spin a bit more to ensure they are all running on separate CPUs.
+ doWork(Millisecond)
+ wg.Done()
+ }()
+ }
+ wg.Wait()
+}
+
+func doWork(dur Duration) {
+ start := Now()
+ for Since(start) < dur {
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-23 03:51:32 +0000