14.6 协程和恢复(recover)

恢复是在 panicking 的协程内部的：不能被另外一个协程恢复

func server(workChan <-chan *Work) {
    for work := range workChan {
        go safelyDo(work)   // start the goroutine for that work
    }
}

func safelyDo(work *Work) {
    defer func() {
        if err := recover(); err != nil {
            log.Printf("Work failed with %s in %v", err, work)
        }
    }()
    do(work)
}

如果 do(work) 发生 panic()，错误会被记录且协程会退出并释放，而其他协程不受影响。