167 lines
2.9 KiB
Go
167 lines
2.9 KiB
Go
// Copyright 2009 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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// GOMAXPROCS=10 go test
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package sync_test
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import (
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"runtime"
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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 HammerSemaphore(s *uint32, loops int, cdone chan bool) {
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for i := 0; i < loops; i++ {
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Runtime_Semacquire(s)
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Runtime_Semrelease(s)
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}
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cdone <- true
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}
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func TestSemaphore(t *testing.T) {
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s := new(uint32)
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*s = 1
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c := make(chan bool)
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for i := 0; i < 10; i++ {
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go HammerSemaphore(s, 1000, c)
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}
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for i := 0; i < 10; i++ {
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<-c
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}
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}
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func BenchmarkUncontendedSemaphore(b *testing.B) {
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s := new(uint32)
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*s = 1
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HammerSemaphore(s, b.N, make(chan bool, 2))
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}
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func BenchmarkContendedSemaphore(b *testing.B) {
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b.StopTimer()
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s := new(uint32)
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*s = 1
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c := make(chan bool)
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defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(2))
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b.StartTimer()
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go HammerSemaphore(s, b.N/2, c)
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go HammerSemaphore(s, b.N/2, c)
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<-c
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<-c
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}
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func HammerMutex(m *Mutex, loops int, cdone chan bool) {
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for i := 0; i < loops; i++ {
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m.Lock()
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m.Unlock()
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}
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cdone <- true
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}
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func TestMutex(t *testing.T) {
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m := new(Mutex)
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c := make(chan bool)
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for i := 0; i < 10; i++ {
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go HammerMutex(m, 1000, c)
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}
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for i := 0; i < 10; i++ {
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<-c
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}
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}
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func TestMutexPanic(t *testing.T) {
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defer func() {
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if recover() == nil {
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t.Fatalf("unlock of unlocked mutex did not panic")
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}
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}()
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var mu Mutex
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mu.Lock()
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mu.Unlock()
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mu.Unlock()
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}
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func BenchmarkMutexUncontended(b *testing.B) {
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type PaddedMutex struct {
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Mutex
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pad [128]uint8
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}
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const CallsPerSched = 1000
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procs := runtime.GOMAXPROCS(-1)
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N := int32(b.N / CallsPerSched)
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c := make(chan bool, procs)
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for p := 0; p < procs; p++ {
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go func() {
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var mu PaddedMutex
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for atomic.AddInt32(&N, -1) >= 0 {
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runtime.Gosched()
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for g := 0; g < CallsPerSched; g++ {
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mu.Lock()
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mu.Unlock()
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}
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}
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c <- true
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}()
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}
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for p := 0; p < procs; p++ {
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<-c
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}
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}
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func benchmarkMutex(b *testing.B, slack, work bool) {
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const (
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CallsPerSched = 1000
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LocalWork = 100
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GoroutineSlack = 10
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)
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procs := runtime.GOMAXPROCS(-1)
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if slack {
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procs *= GoroutineSlack
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}
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N := int32(b.N / CallsPerSched)
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c := make(chan bool, procs)
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var mu Mutex
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for p := 0; p < procs; p++ {
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go func() {
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foo := 0
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for atomic.AddInt32(&N, -1) >= 0 {
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runtime.Gosched()
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for g := 0; g < CallsPerSched; g++ {
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mu.Lock()
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mu.Unlock()
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if work {
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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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}
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}
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c <- foo == 42
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}()
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}
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for p := 0; p < procs; p++ {
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<-c
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}
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}
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func BenchmarkMutex(b *testing.B) {
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benchmarkMutex(b, false, false)
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}
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func BenchmarkMutexSlack(b *testing.B) {
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benchmarkMutex(b, true, false)
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}
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func BenchmarkMutexWork(b *testing.B) {
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benchmarkMutex(b, false, true)
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}
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func BenchmarkMutexWorkSlack(b *testing.B) {
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benchmarkMutex(b, true, true)
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}
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