golang race

原文链接

由于golang中的go是非常方便的，加上函数又非常容易隐藏go

package main

import(
    "time"
    "fmt"
    "math/rand"
)

func main() {
    start := time.Now()
    var t *time.Timer
    t = time.AfterFunc(randomDuration(), func() {
        fmt.Println(time.Now().Sub(start))
        t.Reset(randomDuration())
    })
    time.Sleep(5 * time.Second)
}

func randomDuration() time.Duration {
    return time.Duration(rand.Int63n(1e9))
}

time.AfterFunc是会另外启动一个goroutine来进行计时和执行func()。 由于func中有对t(Timer)进行操作(t.Reset)，而主goroutine也有对t进行操作(t=time.After)。 这个时候，其实有可能会造成两个goroutine对同一个变量进行竞争的情况

runtime  go run -race race1.go
a is  3
==================
WARNING: DATA RACE
Write by goroutine 5:
  main.func·001()
      /Users/yejianfeng/Documents/workspace/go/src/runtime/race1.go:11 +0x3a

Previous write by main goroutine:
  main.main()
      /Users/yejianfeng/Documents/workspace/go/src/runtime/race1.go:13 +0xe7

Goroutine 5 (running) created at:
  main.main()
      /Users/yejianfeng/Documents/workspace/go/src/runtime/race1.go:12 +0xd7
==================
Found 1 data race(s)
exit status 66

通过race的参数，检测相关参数的竞争问题