goroutine记忆泄漏

Question

我不明白为什么内存不被释放。内存配置文件显示runtime.malg使用的几乎所有内存。如果我在DoSomeWork中移除通道上的范围，一切都可以正常工作。

这里是fmt.Println的输出：

Memory Acquired:  4196600
Memory Used    :  745192

Memory Acquired:  2651299576
Memory Used    :  393923440

源代码：

func DoSomeWork(work chan int) {
    for _ = range work {
    }
}

func main() {
    k := make(chan int)
    m := &runtime.MemStats{}
    runtime.ReadMemStats(m)
    fmt.Println("Memory Acquired: ", m.Sys)
    fmt.Println("Memory Used    : ", m.Alloc)

    wg := new(sync.WaitGroup)
    // generate a lot of goroutines that reads from channel
    for i:=0;i<1000000;i++ {
        wg.Add(1)
        go func() {
            DoSomeWork(k)
            wg.Done()
        }()
    }

    close(k)
    wg.Wait()

    // make GC
    runtime.GC()

    // show memory after garbage collector
    runtime.ReadMemStats(m)
    fmt.Println("Memory Acquired: ", m.Sys)
    fmt.Println("Memory Used    : ", m.Alloc)
}

Answer 1

您的代码中没有内存泄漏。然而，您确实会导致大量内存被保留，这就是您所看到的。

当我寻找任何泄漏时，我宁愿多做一次测试。这很容易用您的代码完成。只需添加：

func init(){
    for{
        main()
    }
}

新的输出将显示在运行过程中内存没有丢失：

Memory Acquired:  2885880
Memory Used    :  14848
Memory Acquired:  2594885728
Memory Used    :  297108312
Memory Acquired:  2594885728
Memory Used    :  297108984
Memory Acquired:  2624143456
Memory Used    :  297108312
Memory Acquired:  2624143456
Memory Used    :  297108984
Memory Acquired:  2624143456
Memory Used    :  297108312
Memory Acquired:  2624143456
Memory Used    :  297108984
Memory Acquired:  2624143456
Memory Used    :  297108312
Memory Acquired:  2624143456
Memory Used    :  297108984
Memory Acquired:  2624143456
Memory Used    :  297108312