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-rw-r--r--src/runtime/gc_test.go802
1 files changed, 802 insertions, 0 deletions
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)
+}
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