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// run
// Copyright 2014 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.
// Scenario that used to leak arbitrarily many SudoG structs.
// See golang.org/issue/9110.
package main
import (
"runtime"
"runtime/debug"
"sync"
"time"
)
func main() {
debug.SetGCPercent(1000000) // only GC when we ask for GC
var stats, stats1, stats2 runtime.MemStats
release := func() {}
for i := 0; i < 20; i++ {
if i == 10 {
// Should be warmed up by now.
runtime.ReadMemStats(&stats1)
}
c := make(chan int)
for i := 0; i < 10; i++ {
go func() {
select {
case <-c:
case <-c:
case <-c:
}
}()
}
time.Sleep(1 * time.Millisecond)
release()
close(c) // let select put its sudog's into the cache
time.Sleep(1 * time.Millisecond)
// pick up top sudog
var cond1 sync.Cond
var mu1 sync.Mutex
cond1.L = &mu1
go func() {
mu1.Lock()
cond1.Wait()
mu1.Unlock()
}()
time.Sleep(1 * time.Millisecond)
// pick up next sudog
var cond2 sync.Cond
var mu2 sync.Mutex
cond2.L = &mu2
go func() {
mu2.Lock()
cond2.Wait()
mu2.Unlock()
}()
time.Sleep(1 * time.Millisecond)
// put top sudog back
cond1.Broadcast()
time.Sleep(1 * time.Millisecond)
// drop cache on floor
runtime.GC()
// release cond2 after select has gotten to run
release = func() {
cond2.Broadcast()
time.Sleep(1 * time.Millisecond)
}
}
runtime.GC()
runtime.ReadMemStats(&stats2)
if int(stats2.HeapObjects)-int(stats1.HeapObjects) > 20 { // normally at most 1 or 2; was 300 with leak
print("BUG: object leak: ", stats.HeapObjects, " -> ", stats1.HeapObjects, " -> ", stats2.HeapObjects, "\n")
}
}
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