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// 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 sync_test
import (
"internal/race"
"runtime"
. "sync"
"sync/atomic"
"testing"
)
func testWaitGroup(t *testing.T, wg1 *WaitGroup, wg2 *WaitGroup) {
n := 16
wg1.Add(n)
wg2.Add(n)
exited := make(chan bool, n)
for i := 0; i != n; i++ {
go func(i int) {
wg1.Done()
wg2.Wait()
exited <- true
}(i)
}
wg1.Wait()
for i := 0; i != n; i++ {
select {
case <-exited:
t.Fatal("WaitGroup released group too soon")
default:
}
wg2.Done()
}
for i := 0; i != n; i++ {
<-exited // Will block if barrier fails to unlock someone.
}
}
func TestWaitGroup(t *testing.T) {
wg1 := &WaitGroup{}
wg2 := &WaitGroup{}
// Run the same test a few times to ensure barrier is in a proper state.
for i := 0; i != 8; i++ {
testWaitGroup(t, wg1, wg2)
}
}
func knownRacy(t *testing.T) {
if race.Enabled {
t.Skip("skipping known-racy test under the race detector")
}
}
func TestWaitGroupMisuse(t *testing.T) {
defer func() {
err := recover()
if err != "sync: negative WaitGroup counter" {
t.Fatalf("Unexpected panic: %#v", err)
}
}()
wg := &WaitGroup{}
wg.Add(1)
wg.Done()
wg.Done()
t.Fatal("Should panic")
}
func TestWaitGroupMisuse2(t *testing.T) {
knownRacy(t)
if testing.Short() {
t.Skip("skipping flaky test in short mode; see issue 11443")
}
if runtime.NumCPU() <= 2 {
t.Skip("NumCPU<=2, skipping: this test requires parallelism")
}
defer func() {
err := recover()
if err != "sync: negative WaitGroup counter" &&
err != "sync: WaitGroup misuse: Add called concurrently with Wait" &&
err != "sync: WaitGroup is reused before previous Wait has returned" {
t.Fatalf("Unexpected panic: %#v", err)
}
}()
defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(4))
done := make(chan interface{}, 2)
// The detection is opportunistically, so we want it to panic
// at least in one run out of a million.
for i := 0; i < 1e6; i++ {
var wg WaitGroup
wg.Add(1)
go func() {
defer func() {
done <- recover()
}()
wg.Wait()
}()
go func() {
defer func() {
done <- recover()
}()
wg.Add(1) // This is the bad guy.
wg.Done()
}()
wg.Done()
for j := 0; j < 2; j++ {
if err := <-done; err != nil {
panic(err)
}
}
}
t.Fatal("Should panic")
}
func TestWaitGroupMisuse3(t *testing.T) {
knownRacy(t)
if runtime.NumCPU() <= 1 {
t.Skip("NumCPU==1, skipping: this test requires parallelism")
}
defer func() {
err := recover()
if err != "sync: negative WaitGroup counter" &&
err != "sync: WaitGroup misuse: Add called concurrently with Wait" &&
err != "sync: WaitGroup is reused before previous Wait has returned" {
t.Fatalf("Unexpected panic: %#v", err)
}
}()
defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(4))
done := make(chan interface{}, 1)
// The detection is opportunistically, so we want it to panic
// at least in one run out of a million.
for i := 0; i < 1e6; i++ {
var wg WaitGroup
wg.Add(1)
go func() {
wg.Done()
}()
go func() {
defer func() {
done <- recover()
}()
wg.Wait()
// Start reusing the wg before waiting for the Wait below to return.
wg.Add(1)
go func() {
wg.Done()
}()
wg.Wait()
}()
wg.Wait()
if err := <-done; err != nil {
panic(err)
}
}
t.Fatal("Should panic")
}
func TestWaitGroupRace(t *testing.T) {
// Run this test for about 1ms.
for i := 0; i < 1000; i++ {
wg := &WaitGroup{}
n := new(int32)
// spawn goroutine 1
wg.Add(1)
go func() {
atomic.AddInt32(n, 1)
wg.Done()
}()
// spawn goroutine 2
wg.Add(1)
go func() {
atomic.AddInt32(n, 1)
wg.Done()
}()
// Wait for goroutine 1 and 2
wg.Wait()
if atomic.LoadInt32(n) != 2 {
t.Fatal("Spurious wakeup from Wait")
}
}
}
func TestWaitGroupAlign(t *testing.T) {
type X struct {
x byte
wg WaitGroup
}
var x X
x.wg.Add(1)
go func(x *X) {
x.wg.Done()
}(&x)
x.wg.Wait()
}
func BenchmarkWaitGroupUncontended(b *testing.B) {
type PaddedWaitGroup struct {
WaitGroup
pad [128]uint8
}
b.RunParallel(func(pb *testing.PB) {
var wg PaddedWaitGroup
for pb.Next() {
wg.Add(1)
wg.Done()
wg.Wait()
}
})
}
func benchmarkWaitGroupAddDone(b *testing.B, localWork int) {
var wg WaitGroup
b.RunParallel(func(pb *testing.PB) {
foo := 0
for pb.Next() {
wg.Add(1)
for i := 0; i < localWork; i++ {
foo *= 2
foo /= 2
}
wg.Done()
}
_ = foo
})
}
func BenchmarkWaitGroupAddDone(b *testing.B) {
benchmarkWaitGroupAddDone(b, 0)
}
func BenchmarkWaitGroupAddDoneWork(b *testing.B) {
benchmarkWaitGroupAddDone(b, 100)
}
func benchmarkWaitGroupWait(b *testing.B, localWork int) {
var wg WaitGroup
b.RunParallel(func(pb *testing.PB) {
foo := 0
for pb.Next() {
wg.Wait()
for i := 0; i < localWork; i++ {
foo *= 2
foo /= 2
}
}
_ = foo
})
}
func BenchmarkWaitGroupWait(b *testing.B) {
benchmarkWaitGroupWait(b, 0)
}
func BenchmarkWaitGroupWaitWork(b *testing.B) {
benchmarkWaitGroupWait(b, 100)
}
func BenchmarkWaitGroupActuallyWait(b *testing.B) {
b.ReportAllocs()
b.RunParallel(func(pb *testing.PB) {
for pb.Next() {
var wg WaitGroup
wg.Add(1)
go func() {
wg.Done()
}()
wg.Wait()
}
})
}
|
