175 lines
3 KiB
Go
175 lines
3 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package sync_test
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import (
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. "sync"
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"sync/atomic"
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"testing"
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)
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func testWaitGroup(t *testing.T, wg1 *WaitGroup, wg2 *WaitGroup) {
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n := 16
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wg1.Add(n)
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wg2.Add(n)
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exited := make(chan bool, n)
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for i := 0; i != n; i++ {
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go func() {
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wg1.Done()
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wg2.Wait()
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exited <- true
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}()
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}
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wg1.Wait()
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for i := 0; i != n; i++ {
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select {
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case <-exited:
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t.Fatal("WaitGroup released group too soon")
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default:
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}
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wg2.Done()
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}
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for i := 0; i != n; i++ {
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<-exited // Will block if barrier fails to unlock someone.
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}
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}
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func TestWaitGroup(t *testing.T) {
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wg1 := &WaitGroup{}
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wg2 := &WaitGroup{}
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// Run the same test a few times to ensure barrier is in a proper state.
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for i := 0; i != 8; i++ {
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testWaitGroup(t, wg1, wg2)
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}
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}
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func TestWaitGroupMisuse(t *testing.T) {
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defer func() {
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err := recover()
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if err != "sync: negative WaitGroup counter" {
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t.Fatalf("Unexpected panic: %#v", err)
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}
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}()
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wg := &WaitGroup{}
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wg.Add(1)
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wg.Done()
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wg.Done()
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t.Fatal("Should panic")
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}
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func TestWaitGroupRace(t *testing.T) {
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// Run this test for about 1ms.
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for i := 0; i < 1000; i++ {
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wg := &WaitGroup{}
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n := new(int32)
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// spawn goroutine 1
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wg.Add(1)
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go func() {
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atomic.AddInt32(n, 1)
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wg.Done()
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}()
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// spawn goroutine 2
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wg.Add(1)
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go func() {
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atomic.AddInt32(n, 1)
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wg.Done()
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}()
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// Wait for goroutine 1 and 2
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wg.Wait()
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if atomic.LoadInt32(n) != 2 {
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t.Fatal("Spurious wakeup from Wait")
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}
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}
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}
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func TestWaitGroupAlign(t *testing.T) {
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type X struct {
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x byte
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wg WaitGroup
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}
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var x X
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x.wg.Add(1)
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go func(x *X) {
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x.wg.Done()
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}(&x)
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x.wg.Wait()
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}
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func BenchmarkWaitGroupUncontended(b *testing.B) {
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type PaddedWaitGroup struct {
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WaitGroup
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pad [128]uint8
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}
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b.RunParallel(func(pb *testing.PB) {
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var wg PaddedWaitGroup
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for pb.Next() {
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wg.Add(1)
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wg.Done()
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wg.Wait()
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}
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})
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}
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func benchmarkWaitGroupAddDone(b *testing.B, localWork int) {
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var wg WaitGroup
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b.RunParallel(func(pb *testing.PB) {
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foo := 0
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for pb.Next() {
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wg.Add(1)
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for i := 0; i < localWork; i++ {
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foo *= 2
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foo /= 2
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}
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wg.Done()
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}
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_ = foo
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})
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}
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func BenchmarkWaitGroupAddDone(b *testing.B) {
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benchmarkWaitGroupAddDone(b, 0)
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}
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func BenchmarkWaitGroupAddDoneWork(b *testing.B) {
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benchmarkWaitGroupAddDone(b, 100)
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}
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func benchmarkWaitGroupWait(b *testing.B, localWork int) {
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var wg WaitGroup
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b.RunParallel(func(pb *testing.PB) {
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foo := 0
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for pb.Next() {
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wg.Wait()
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for i := 0; i < localWork; i++ {
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foo *= 2
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foo /= 2
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}
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}
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_ = foo
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})
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}
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func BenchmarkWaitGroupWait(b *testing.B) {
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benchmarkWaitGroupWait(b, 0)
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}
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func BenchmarkWaitGroupWaitWork(b *testing.B) {
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benchmarkWaitGroupWait(b, 100)
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}
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func BenchmarkWaitGroupActuallyWait(b *testing.B) {
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b.ReportAllocs()
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b.RunParallel(func(pb *testing.PB) {
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for pb.Next() {
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var wg WaitGroup
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wg.Add(1)
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go func() {
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wg.Done()
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}()
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wg.Wait()
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}
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})
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}
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