go - 为什么计时器停止会产生死锁错误？

Question

我正在创建此功能以测试创建和停止计时器。运行时出现死锁错误:

package main

import "fmt"
import "time"


func main() {
    livenessTimer := &time.Timer{}
    livenessInterval, _ := time.ParseDuration("1m")
    for {
        fmt.Print("Timer started")
        livenessTimer = time.NewTimer(livenessInterval)
        select {
        case <-livenessTimer.C:
            fmt.Print(time.Now())
            fmt.Println("timer triggered")
        }
        if !livenessTimer.Stop() {
            // drain timer from channel if any
            fmt.Println("drain timer")
            <-livenessTimer.C
        }
    }
}

当我运行此代码时，出现以下错误:

Timer started2009-11-10 23:01:00 +0000 UTC m=+60.000000001timer triggered
drain timer
fatal error: all goroutines are asleep - deadlock!

goroutine 1 [chan receive]:
main.main()
    /tmp/sandbox748850751/prog.go:21 +0x2e0

Stop的文档建议检查返回值并耗尽 channel 。

Answer 1

这是文档中的关键部分:

...assuming the program has not received from t.C already

在您的情况下，计时器已启动，Stop返回false，您开始在没有其他goroutine运行的 channel 上等待，从而导致死锁。