// 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"
"os"
"reflect"
"runtime"
"runtime/debug"
"sync"
"sync/atomic"
"testing"
"time"
"unsafe"
)
func TestGcSys(t *testing.T) {
if os.Getenv("GOGC") == "off" {
t.Skip("skipping test; GOGC=off in environment")
}
if runtime.GOOS == "windows" {
t.Skip("skipping test; GOOS=windows http://golang.org/issue/27156")
}
if runtime.GOOS == "linux" && runtime.GOARCH == "arm64" {
t.Skip("skipping test; GOOS=linux GOARCH=arm64 https://github.com/golang/go/issues/27636")
}
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 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 TestUnscavHugePages(t *testing.T) {
// Allocate 20 MiB and immediately free it a few times to increase
// the chance that unscavHugePages isn't zero and that some kind of
// accounting had to happen in the runtime.
for j := 0; j < 3; j++ {
var large [][]byte
for i := 0; i < 5; i++ {
large = append(large, make([]byte, runtime.PhysHugePageSize))
}
runtime.KeepAlive(large)
runtime.GC()
}
base, slow := runtime.UnscavHugePagesSlow()
if base != slow {
logDiff(t, "unscavHugePages", reflect.ValueOf(base), reflect.ValueOf(slow))
t.Fatal("unscavHugePages 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 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 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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