Question

类似的代码：

    m := make(map[interface{}]interface{})
    //read
    for i := 0; i< 10000; i++ {
        go func() {
            for range m {

            }
        }()
    }
    //write
    for i := 0; i< 10000; i++ {
        go func() {
            mTemp := make(map[interface{}]interface{})
            m = mTemp
        }()
    }

有10000个读goroutine访问m，另一个10000个写goroutine访问m，这是安全的吗？

Answer 1

您有goroutines读取m变量，而goroutines则写入m变量而没有显式同步。这是一场数据竞赛，因此行为不确定。

在启用种族检测器的情况下运行它：

$ go run -race play.go
==================
WARNING: DATA RACE
Write at 0x00c00008c000 by goroutine 15:
  main.main.func2()
      /home/icza/gows/src/play/play.go:17 +0x46

Previous read at 0x00c00008c000 by goroutine 5:
  main.main.func1()
      /home/icza/gows/src/play/play.go:8 +0x45

Goroutine 15 (running) created at:
  main.main()
      /home/icza/gows/src/play/play.go:15 +0xdd

Goroutine 5 (finished) created at:
  main.main()
      /home/icza/gows/src/play/play.go:7 +0xa4
==================
Found 1 data race(s)
exit status 66

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