Should My Go Main Goroutine Sleep Forever or Gracefully Quit?

Main Goroutine's Dilemma: Sleep or Quit?

Developers often encounter the need to keep their Go project constantly running, resembling an eternal flame that never fizzles out. Conversely, there are instances when one desires to gracefully end the program's execution. This article explores the options available for these scenarios.

"Sleeping" the Main Goroutine

To render the main goroutine dormant, several constructs exist that effectively block its execution without consuming CPU resources. Consider the following examples:

• Select without Cases:

  select{}

• Receiving from an Empty Channel:

  <-make(chan int)

• Receiving from a Nil Channel:

  <-(chan int)(nil)

• Sending to a Nil Channel:

  (chan int)(nil) <- 0

• Locking a Locked Mutex:

  mu := sync.Mutex{}
  mu.Lock()
  mu.Lock()

Inducing the End: Quitting the Goroutine

If the objective is to provide a means for termination, introducing a quit channel is a viable approach. Within the main goroutine, the code can wait indefinitely for a signal from this channel. When the time is ripe, the quit channel can be closed:

var quit = make(chan struct{})

func main() {
    // Startup code...

    // Block until the quit signal arrives:
    <-quit
}

// In a separate goroutine, when termination is requested:
close(quit)

Note: Closing the quit channel can trigger the program's immediate termination, as per the Go program execution specification.

Non-Blocking Sleep

In cases where blocking the main goroutine is not desirable, an alternative is to employ time.Sleep() with an extensive duration. The maximum permissible duration is approximately 292 years:

time.Sleep(time.Duration(1<<63 - 1))

For programs destined to outlast this duration, an infinite loop can be implemented:

for {
    time.Sleep(time.Duration(1<<63 - 1))
}

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