如何等待恐慌的goroutine？

Question

A common way to wait for a goroutine is to use a *sync.WaitGroup:

func main() {
    wg := &sync.WaitGroup{}
    wg.Add(1)
    go func() {
        defer wg.Done()
        // Long running task
    }()
    wg.Wait()
}

No problems here. However, what about this:

func main() {
    wg := &sync.WaitGroup{}
    wg.Add(1)
    go func() {
        defer wg.Done()
        // Long running task
        panic("Something unexpected happened.")
    }()
    wg.Wait()
}

In this case, when wg.Done() is called, I believe main() could exit without details of panic() ever being written to stdout/stderr. Is this true and if yes, how might I prevent it from happening?

Answer 1

The panic will kill the process regardless, because no one is recovering from it. If you want to recover from panics in a goroutine, you must have recover wrapping the call stack in the same goroutine.

wg.Done will be called in this case, by the defer statement. But the process may die before the main goroutine finishes the wg.Wait anyway.