Retro68/gcc/libgo/misc/cgo/test/test27660.go

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2019-06-02 15:48:37 +00:00
// Copyright 2018 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.
// Stress the interaction between the race detector and cgo in an
// attempt to reproduce the memory corruption described in #27660.
// The bug was very timing sensitive; at the time of writing this
// test would only trigger the bug about once out of every five runs.
package cgotest
// #include <unistd.h>
import "C"
import (
"context"
"math/rand"
"runtime"
"sync"
"testing"
"time"
)
func test27660(t *testing.T) {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
ints := make([]int, 100)
locks := make([]sync.Mutex, 100)
// Slowly create threads so that ThreadSanitizer is forced to
// frequently resize its SyncClocks.
for i := 0; i < 100; i++ {
go func() {
for ctx.Err() == nil {
// Sleep in C for long enough that it is likely that the runtime
// will retake this goroutine's currently wired P.
C.usleep(1000 /* 1ms */)
runtime.Gosched() // avoid starvation (see #28701)
}
}()
go func() {
// Trigger lots of synchronization and memory reads/writes to
// increase the likelihood that the race described in #27660
// results in corruption of ThreadSanitizer's internal state
// and thus an assertion failure or segfault.
i := 0
for ctx.Err() == nil {
j := rand.Intn(100)
locks[j].Lock()
ints[j]++
locks[j].Unlock()
// Avoid making the loop unpreemptible
// for gccgo.
if i%0x1000000 == 0 {
runtime.Gosched()
}
i++
}
}()
time.Sleep(time.Millisecond)
}
}