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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 runtime_test
import (
"runtime"
"sync/atomic"
"testing"
)
var stop = make(chan bool, 1)
func perpetuumMobile() {
select {
case <-stop:
default:
go perpetuumMobile()
}
}
func TestStopTheWorldDeadlock(t *testing.T) {
if testing.Short() {
t.Logf("skipping during short test")
return
}
maxprocs := runtime.GOMAXPROCS(3)
compl := make(chan bool, 2)
go func() {
for i := 0; i != 1000; i += 1 {
runtime.GC()
}
compl <- true
}()
go func() {
for i := 0; i != 1000; i += 1 {
runtime.GOMAXPROCS(3)
}
compl <- true
}()
go perpetuumMobile()
<-compl
<-compl
stop <- true
runtime.GOMAXPROCS(maxprocs)
}
func stackGrowthRecursive(i int) {
var pad [128]uint64
if i != 0 && pad[0] == 0 {
stackGrowthRecursive(i - 1)
}
}
func BenchmarkStackGrowth(b *testing.B) {
const CallsPerSched = 1000
procs := runtime.GOMAXPROCS(-1)
N := int32(b.N / CallsPerSched)
c := make(chan bool, procs)
for p := 0; p < procs; p++ {
go func() {
for atomic.AddInt32(&N, -1) >= 0 {
runtime.Gosched()
for g := 0; g < CallsPerSched; g++ {
stackGrowthRecursive(10)
}
}
c <- true
}()
}
for p := 0; p < procs; p++ {
<-c
}
}
func BenchmarkSyscall(b *testing.B) {
const CallsPerSched = 1000
procs := runtime.GOMAXPROCS(-1)
N := int32(b.N / CallsPerSched)
c := make(chan bool, procs)
for p := 0; p < procs; p++ {
go func() {
for atomic.AddInt32(&N, -1) >= 0 {
runtime.Gosched()
for g := 0; g < CallsPerSched; g++ {
runtime.Entersyscall()
runtime.Exitsyscall()
}
}
c <- true
}()
}
for p := 0; p < procs; p++ {
<-c
}
}
func BenchmarkSyscallWork(b *testing.B) {
const CallsPerSched = 1000
const LocalWork = 100
procs := runtime.GOMAXPROCS(-1)
N := int32(b.N / CallsPerSched)
c := make(chan bool, procs)
for p := 0; p < procs; p++ {
go func() {
foo := 42
for atomic.AddInt32(&N, -1) >= 0 {
runtime.Gosched()
for g := 0; g < CallsPerSched; g++ {
runtime.Entersyscall()
for i := 0; i < LocalWork; i++ {
foo *= 2
foo /= 2
}
runtime.Exitsyscall()
}
}
c <- foo == 42
}()
}
for p := 0; p < procs; p++ {
<-c
}
}
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