发起goroutine（即调用“ go”）会失败吗？

Question

Is it possible to fail when executing go f?

Since the keyword go has no return value, how to determine whether a goroutine is successfully started during high concurrency?

For Example:

package main

import (
    "fmt"
    "sync"
    "time"
)

func main() {
    var wg = &sync.WaitGroup{}
    go func() { // How do I know if there is any failure here?
        wg.Add(1)
        fmt.Println("halo world")
        wg.Done()
    }()
    time.Sleep(time.Nanosecond)
    wg.Wait()
}

Answer 1

The go statement cannot fail (only in "extreme" circumstances like out of memory, but then a failing go statement would be the least of your problems).

Of course without synchronization you don't have guarantee when that goroutine is scheduled to run. Your example use of sync.WaitGroup therefore is incorrect, as if the goroutine is not scheduled until the main goroutine reaches wg.Wait(), it may never even start, as when the main goroutine ends, your program ends as well.

Instead increment the WaitGroup's counter in the main goroutine (and it's best to call WaitGroup.Done() deferred, so it gets called even if the goroutine would panic):

var wg = &sync.WaitGroup{}
wg.Add(1)
go func() {
    defer wg.Done()
    fmt.Println("halo world")
}()
wg.Wait()

That way you don't even need the sleep, wg.Wait() will block until the other goroutine calls wg.Done() (which will happen only when the other goroutine completed its work).