From 73df946d56c74384511a194dd01dbe099584fd1a Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 28 Apr 2024 15:14:23 +0200 Subject: Adding upstream version 1.16.10. Signed-off-by: Daniel Baumann --- src/runtime/gc_test.go | 802 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 802 insertions(+) create mode 100644 src/runtime/gc_test.go (limited to 'src/runtime/gc_test.go') diff --git a/src/runtime/gc_test.go b/src/runtime/gc_test.go new file mode 100644 index 0000000..7870f31 --- /dev/null +++ b/src/runtime/gc_test.go @@ -0,0 +1,802 @@ +// Copyright 2011 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 runtime_test + +import ( + "fmt" + "math/rand" + "os" + "reflect" + "runtime" + "runtime/debug" + "sort" + "strings" + "sync" + "sync/atomic" + "testing" + "time" + "unsafe" +) + +func TestGcSys(t *testing.T) { + if os.Getenv("GOGC") == "off" { + t.Skip("skipping test; GOGC=off in environment") + } + got := runTestProg(t, "testprog", "GCSys") + want := "OK\n" + if got != want { + t.Fatalf("expected %q, but got %q", want, got) + } +} + +func TestGcDeepNesting(t *testing.T) { + type T [2][2][2][2][2][2][2][2][2][2]*int + a := new(T) + + // Prevent the compiler from applying escape analysis. + // This makes sure new(T) is allocated on heap, not on the stack. + t.Logf("%p", a) + + a[0][0][0][0][0][0][0][0][0][0] = new(int) + *a[0][0][0][0][0][0][0][0][0][0] = 13 + runtime.GC() + if *a[0][0][0][0][0][0][0][0][0][0] != 13 { + t.Fail() + } +} + +func TestGcMapIndirection(t *testing.T) { + defer debug.SetGCPercent(debug.SetGCPercent(1)) + runtime.GC() + type T struct { + a [256]int + } + m := make(map[T]T) + for i := 0; i < 2000; i++ { + var a T + a.a[0] = i + m[a] = T{} + } +} + +func TestGcArraySlice(t *testing.T) { + type X struct { + buf [1]byte + nextbuf []byte + next *X + } + var head *X + for i := 0; i < 10; i++ { + p := &X{} + p.buf[0] = 42 + p.next = head + if head != nil { + p.nextbuf = head.buf[:] + } + head = p + runtime.GC() + } + for p := head; p != nil; p = p.next { + if p.buf[0] != 42 { + t.Fatal("corrupted heap") + } + } +} + +func TestGcRescan(t *testing.T) { + type X struct { + c chan error + nextx *X + } + type Y struct { + X + nexty *Y + p *int + } + var head *Y + for i := 0; i < 10; i++ { + p := &Y{} + p.c = make(chan error) + if head != nil { + p.nextx = &head.X + } + p.nexty = head + p.p = new(int) + *p.p = 42 + head = p + runtime.GC() + } + for p := head; p != nil; p = p.nexty { + if *p.p != 42 { + t.Fatal("corrupted heap") + } + } +} + +func TestGcLastTime(t *testing.T) { + ms := new(runtime.MemStats) + t0 := time.Now().UnixNano() + runtime.GC() + t1 := time.Now().UnixNano() + runtime.ReadMemStats(ms) + last := int64(ms.LastGC) + if t0 > last || last > t1 { + t.Fatalf("bad last GC time: got %v, want [%v, %v]", last, t0, t1) + } + pause := ms.PauseNs[(ms.NumGC+255)%256] + // Due to timer granularity, pause can actually be 0 on windows + // or on virtualized environments. + if pause == 0 { + t.Logf("last GC pause was 0") + } else if pause > 10e9 { + t.Logf("bad last GC pause: got %v, want [0, 10e9]", pause) + } +} + +var hugeSink interface{} + +func TestHugeGCInfo(t *testing.T) { + // The test ensures that compiler can chew these huge types even on weakest machines. + // The types are not allocated at runtime. + if hugeSink != nil { + // 400MB on 32 bots, 4TB on 64-bits. + const n = (400 << 20) + (unsafe.Sizeof(uintptr(0))-4)<<40 + hugeSink = new([n]*byte) + hugeSink = new([n]uintptr) + hugeSink = new(struct { + x float64 + y [n]*byte + z []string + }) + hugeSink = new(struct { + x float64 + y [n]uintptr + z []string + }) + } +} + +func TestPeriodicGC(t *testing.T) { + if runtime.GOARCH == "wasm" { + t.Skip("no sysmon on wasm yet") + } + + // Make sure we're not in the middle of a GC. + runtime.GC() + + var ms1, ms2 runtime.MemStats + runtime.ReadMemStats(&ms1) + + // Make periodic GC run continuously. + orig := *runtime.ForceGCPeriod + *runtime.ForceGCPeriod = 0 + + // Let some periodic GCs happen. In a heavily loaded system, + // it's possible these will be delayed, so this is designed to + // succeed quickly if things are working, but to give it some + // slack if things are slow. + var numGCs uint32 + const want = 2 + for i := 0; i < 200 && numGCs < want; i++ { + time.Sleep(5 * time.Millisecond) + + // Test that periodic GC actually happened. + runtime.ReadMemStats(&ms2) + numGCs = ms2.NumGC - ms1.NumGC + } + *runtime.ForceGCPeriod = orig + + if numGCs < want { + t.Fatalf("no periodic GC: got %v GCs, want >= 2", numGCs) + } +} + +func TestGcZombieReporting(t *testing.T) { + // This test is somewhat sensitive to how the allocator works. + got := runTestProg(t, "testprog", "GCZombie") + want := "found pointer to free object" + if !strings.Contains(got, want) { + t.Fatalf("expected %q in output, but got %q", want, got) + } +} + +func BenchmarkSetTypePtr(b *testing.B) { + benchSetType(b, new(*byte)) +} + +func BenchmarkSetTypePtr8(b *testing.B) { + benchSetType(b, new([8]*byte)) +} + +func BenchmarkSetTypePtr16(b *testing.B) { + benchSetType(b, new([16]*byte)) +} + +func BenchmarkSetTypePtr32(b *testing.B) { + benchSetType(b, new([32]*byte)) +} + +func BenchmarkSetTypePtr64(b *testing.B) { + benchSetType(b, new([64]*byte)) +} + +func BenchmarkSetTypePtr126(b *testing.B) { + benchSetType(b, new([126]*byte)) +} + +func BenchmarkSetTypePtr128(b *testing.B) { + benchSetType(b, new([128]*byte)) +} + +func BenchmarkSetTypePtrSlice(b *testing.B) { + benchSetType(b, make([]*byte, 1<<10)) +} + +type Node1 struct { + Value [1]uintptr + Left, Right *byte +} + +func BenchmarkSetTypeNode1(b *testing.B) { + benchSetType(b, new(Node1)) +} + +func BenchmarkSetTypeNode1Slice(b *testing.B) { + benchSetType(b, make([]Node1, 32)) +} + +type Node8 struct { + Value [8]uintptr + Left, Right *byte +} + +func BenchmarkSetTypeNode8(b *testing.B) { + benchSetType(b, new(Node8)) +} + +func BenchmarkSetTypeNode8Slice(b *testing.B) { + benchSetType(b, make([]Node8, 32)) +} + +type Node64 struct { + Value [64]uintptr + Left, Right *byte +} + +func BenchmarkSetTypeNode64(b *testing.B) { + benchSetType(b, new(Node64)) +} + +func BenchmarkSetTypeNode64Slice(b *testing.B) { + benchSetType(b, make([]Node64, 32)) +} + +type Node64Dead struct { + Left, Right *byte + Value [64]uintptr +} + +func BenchmarkSetTypeNode64Dead(b *testing.B) { + benchSetType(b, new(Node64Dead)) +} + +func BenchmarkSetTypeNode64DeadSlice(b *testing.B) { + benchSetType(b, make([]Node64Dead, 32)) +} + +type Node124 struct { + Value [124]uintptr + Left, Right *byte +} + +func BenchmarkSetTypeNode124(b *testing.B) { + benchSetType(b, new(Node124)) +} + +func BenchmarkSetTypeNode124Slice(b *testing.B) { + benchSetType(b, make([]Node124, 32)) +} + +type Node126 struct { + Value [126]uintptr + Left, Right *byte +} + +func BenchmarkSetTypeNode126(b *testing.B) { + benchSetType(b, new(Node126)) +} + +func BenchmarkSetTypeNode126Slice(b *testing.B) { + benchSetType(b, make([]Node126, 32)) +} + +type Node128 struct { + Value [128]uintptr + Left, Right *byte +} + +func BenchmarkSetTypeNode128(b *testing.B) { + benchSetType(b, new(Node128)) +} + +func BenchmarkSetTypeNode128Slice(b *testing.B) { + benchSetType(b, make([]Node128, 32)) +} + +type Node130 struct { + Value [130]uintptr + Left, Right *byte +} + +func BenchmarkSetTypeNode130(b *testing.B) { + benchSetType(b, new(Node130)) +} + +func BenchmarkSetTypeNode130Slice(b *testing.B) { + benchSetType(b, make([]Node130, 32)) +} + +type Node1024 struct { + Value [1024]uintptr + Left, Right *byte +} + +func BenchmarkSetTypeNode1024(b *testing.B) { + benchSetType(b, new(Node1024)) +} + +func BenchmarkSetTypeNode1024Slice(b *testing.B) { + benchSetType(b, make([]Node1024, 32)) +} + +func benchSetType(b *testing.B, x interface{}) { + v := reflect.ValueOf(x) + t := v.Type() + switch t.Kind() { + case reflect.Ptr: + b.SetBytes(int64(t.Elem().Size())) + case reflect.Slice: + b.SetBytes(int64(t.Elem().Size()) * int64(v.Len())) + } + b.ResetTimer() + runtime.BenchSetType(b.N, x) +} + +func BenchmarkAllocation(b *testing.B) { + type T struct { + x, y *byte + } + ngo := runtime.GOMAXPROCS(0) + work := make(chan bool, b.N+ngo) + result := make(chan *T) + for i := 0; i < b.N; i++ { + work <- true + } + for i := 0; i < ngo; i++ { + work <- false + } + for i := 0; i < ngo; i++ { + go func() { + var x *T + for <-work { + for i := 0; i < 1000; i++ { + x = &T{} + } + } + result <- x + }() + } + for i := 0; i < ngo; i++ { + <-result + } +} + +func TestPrintGC(t *testing.T) { + if testing.Short() { + t.Skip("Skipping in short mode") + } + defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(2)) + done := make(chan bool) + go func() { + for { + select { + case <-done: + return + default: + runtime.GC() + } + } + }() + for i := 0; i < 1e4; i++ { + func() { + defer print("") + }() + } + close(done) +} + +func testTypeSwitch(x interface{}) error { + switch y := x.(type) { + case nil: + // ok + case error: + return y + } + return nil +} + +func testAssert(x interface{}) error { + if y, ok := x.(error); ok { + return y + } + return nil +} + +func testAssertVar(x interface{}) error { + var y, ok = x.(error) + if ok { + return y + } + return nil +} + +var a bool + +//go:noinline +func testIfaceEqual(x interface{}) { + if x == "abc" { + a = true + } +} + +func TestPageAccounting(t *testing.T) { + // Grow the heap in small increments. This used to drop the + // pages-in-use count below zero because of a rounding + // mismatch (golang.org/issue/15022). + const blockSize = 64 << 10 + blocks := make([]*[blockSize]byte, (64<<20)/blockSize) + for i := range blocks { + blocks[i] = new([blockSize]byte) + } + + // Check that the running page count matches reality. + pagesInUse, counted := runtime.CountPagesInUse() + if pagesInUse != counted { + t.Fatalf("mheap_.pagesInUse is %d, but direct count is %d", pagesInUse, counted) + } +} + +func TestReadMemStats(t *testing.T) { + base, slow := runtime.ReadMemStatsSlow() + if base != slow { + logDiff(t, "MemStats", reflect.ValueOf(base), reflect.ValueOf(slow)) + t.Fatal("memstats mismatch") + } +} + +func logDiff(t *testing.T, prefix string, got, want reflect.Value) { + typ := got.Type() + switch typ.Kind() { + case reflect.Array, reflect.Slice: + if got.Len() != want.Len() { + t.Logf("len(%s): got %v, want %v", prefix, got, want) + return + } + for i := 0; i < got.Len(); i++ { + logDiff(t, fmt.Sprintf("%s[%d]", prefix, i), got.Index(i), want.Index(i)) + } + case reflect.Struct: + for i := 0; i < typ.NumField(); i++ { + gf, wf := got.Field(i), want.Field(i) + logDiff(t, prefix+"."+typ.Field(i).Name, gf, wf) + } + case reflect.Map: + t.Fatal("not implemented: logDiff for map") + default: + if got.Interface() != want.Interface() { + t.Logf("%s: got %v, want %v", prefix, got, want) + } + } +} + +func BenchmarkReadMemStats(b *testing.B) { + var ms runtime.MemStats + const heapSize = 100 << 20 + x := make([]*[1024]byte, heapSize/1024) + for i := range x { + x[i] = new([1024]byte) + } + hugeSink = x + + b.ResetTimer() + for i := 0; i < b.N; i++ { + runtime.ReadMemStats(&ms) + } + + hugeSink = nil +} + +func applyGCLoad(b *testing.B) func() { + // We’ll apply load to the runtime with maxProcs-1 goroutines + // and use one more to actually benchmark. It doesn't make sense + // to try to run this test with only 1 P (that's what + // BenchmarkReadMemStats is for). + maxProcs := runtime.GOMAXPROCS(-1) + if maxProcs == 1 { + b.Skip("This benchmark can only be run with GOMAXPROCS > 1") + } + + // Code to build a big tree with lots of pointers. + type node struct { + children [16]*node + } + var buildTree func(depth int) *node + buildTree = func(depth int) *node { + tree := new(node) + if depth != 0 { + for i := range tree.children { + tree.children[i] = buildTree(depth - 1) + } + } + return tree + } + + // Keep the GC busy by continuously generating large trees. + done := make(chan struct{}) + var wg sync.WaitGroup + for i := 0; i < maxProcs-1; i++ { + wg.Add(1) + go func() { + defer wg.Done() + var hold *node + loop: + for { + hold = buildTree(5) + select { + case <-done: + break loop + default: + } + } + runtime.KeepAlive(hold) + }() + } + return func() { + close(done) + wg.Wait() + } +} + +func BenchmarkReadMemStatsLatency(b *testing.B) { + stop := applyGCLoad(b) + + // Spend this much time measuring latencies. + latencies := make([]time.Duration, 0, 1024) + + // Run for timeToBench hitting ReadMemStats continuously + // and measuring the latency. + b.ResetTimer() + var ms runtime.MemStats + for i := 0; i < b.N; i++ { + // Sleep for a bit, otherwise we're just going to keep + // stopping the world and no one will get to do anything. + time.Sleep(100 * time.Millisecond) + start := time.Now() + runtime.ReadMemStats(&ms) + latencies = append(latencies, time.Now().Sub(start)) + } + // Make sure to stop the timer before we wait! The load created above + // is very heavy-weight and not easy to stop, so we could end up + // confusing the benchmarking framework for small b.N. + b.StopTimer() + stop() + + // Disable the default */op metrics. + // ns/op doesn't mean anything because it's an average, but we + // have a sleep in our b.N loop above which skews this significantly. + b.ReportMetric(0, "ns/op") + b.ReportMetric(0, "B/op") + b.ReportMetric(0, "allocs/op") + + // Sort latencies then report percentiles. + sort.Slice(latencies, func(i, j int) bool { + return latencies[i] < latencies[j] + }) + b.ReportMetric(float64(latencies[len(latencies)*50/100]), "p50-ns") + b.ReportMetric(float64(latencies[len(latencies)*90/100]), "p90-ns") + b.ReportMetric(float64(latencies[len(latencies)*99/100]), "p99-ns") +} + +func TestUserForcedGC(t *testing.T) { + // Test that runtime.GC() triggers a GC even if GOGC=off. + defer debug.SetGCPercent(debug.SetGCPercent(-1)) + + var ms1, ms2 runtime.MemStats + runtime.ReadMemStats(&ms1) + runtime.GC() + runtime.ReadMemStats(&ms2) + if ms1.NumGC == ms2.NumGC { + t.Fatalf("runtime.GC() did not trigger GC") + } + if ms1.NumForcedGC == ms2.NumForcedGC { + t.Fatalf("runtime.GC() was not accounted in NumForcedGC") + } +} + +func writeBarrierBenchmark(b *testing.B, f func()) { + runtime.GC() + var ms runtime.MemStats + runtime.ReadMemStats(&ms) + //b.Logf("heap size: %d MB", ms.HeapAlloc>>20) + + // Keep GC running continuously during the benchmark, which in + // turn keeps the write barrier on continuously. + var stop uint32 + done := make(chan bool) + go func() { + for atomic.LoadUint32(&stop) == 0 { + runtime.GC() + } + close(done) + }() + defer func() { + atomic.StoreUint32(&stop, 1) + <-done + }() + + b.ResetTimer() + f() + b.StopTimer() +} + +func BenchmarkWriteBarrier(b *testing.B) { + if runtime.GOMAXPROCS(-1) < 2 { + // We don't want GC to take our time. + b.Skip("need GOMAXPROCS >= 2") + } + + // Construct a large tree both so the GC runs for a while and + // so we have a data structure to manipulate the pointers of. + type node struct { + l, r *node + } + var wbRoots []*node + var mkTree func(level int) *node + mkTree = func(level int) *node { + if level == 0 { + return nil + } + n := &node{mkTree(level - 1), mkTree(level - 1)} + if level == 10 { + // Seed GC with enough early pointers so it + // doesn't start termination barriers when it + // only has the top of the tree. + wbRoots = append(wbRoots, n) + } + return n + } + const depth = 22 // 64 MB + root := mkTree(22) + + writeBarrierBenchmark(b, func() { + var stack [depth]*node + tos := -1 + + // There are two write barriers per iteration, so i+=2. + for i := 0; i < b.N; i += 2 { + if tos == -1 { + stack[0] = root + tos = 0 + } + + // Perform one step of reversing the tree. + n := stack[tos] + if n.l == nil { + tos-- + } else { + n.l, n.r = n.r, n.l + stack[tos] = n.l + stack[tos+1] = n.r + tos++ + } + + if i%(1<<12) == 0 { + // Avoid non-preemptible loops (see issue #10958). + runtime.Gosched() + } + } + }) + + runtime.KeepAlive(wbRoots) +} + +func BenchmarkBulkWriteBarrier(b *testing.B) { + if runtime.GOMAXPROCS(-1) < 2 { + // We don't want GC to take our time. + b.Skip("need GOMAXPROCS >= 2") + } + + // Construct a large set of objects we can copy around. + const heapSize = 64 << 20 + type obj [16]*byte + ptrs := make([]*obj, heapSize/unsafe.Sizeof(obj{})) + for i := range ptrs { + ptrs[i] = new(obj) + } + + writeBarrierBenchmark(b, func() { + const blockSize = 1024 + var pos int + for i := 0; i < b.N; i += blockSize { + // Rotate block. + block := ptrs[pos : pos+blockSize] + first := block[0] + copy(block, block[1:]) + block[blockSize-1] = first + + pos += blockSize + if pos+blockSize > len(ptrs) { + pos = 0 + } + + runtime.Gosched() + } + }) + + runtime.KeepAlive(ptrs) +} + +func BenchmarkScanStackNoLocals(b *testing.B) { + var ready sync.WaitGroup + teardown := make(chan bool) + for j := 0; j < 10; j++ { + ready.Add(1) + go func() { + x := 100000 + countpwg(&x, &ready, teardown) + }() + } + ready.Wait() + b.ResetTimer() + for i := 0; i < b.N; i++ { + b.StartTimer() + runtime.GC() + runtime.GC() + b.StopTimer() + } + close(teardown) +} + +func BenchmarkMSpanCountAlloc(b *testing.B) { + // Allocate one dummy mspan for the whole benchmark. + s := runtime.AllocMSpan() + defer runtime.FreeMSpan(s) + + // n is the number of bytes to benchmark against. + // n must always be a multiple of 8, since gcBits is + // always rounded up 8 bytes. + for _, n := range []int{8, 16, 32, 64, 128} { + b.Run(fmt.Sprintf("bits=%d", n*8), func(b *testing.B) { + // Initialize a new byte slice with pseduo-random data. + bits := make([]byte, n) + rand.Read(bits) + + b.ResetTimer() + for i := 0; i < b.N; i++ { + runtime.MSpanCountAlloc(s, bits) + } + }) + } +} + +func countpwg(n *int, ready *sync.WaitGroup, teardown chan bool) { + if *n == 0 { + ready.Done() + <-teardown + return + } + *n-- + countpwg(n, ready, teardown) +} -- cgit v1.2.3