如何避免在此golang程序中出现死锁？

Question

Here is my program which is producing deadlock, how do I avoid it and what is the recommended pattern to handle this kind of situation.

The problem is after timeout how do I detect that there is no reader on my channel ?

var wg sync.WaitGroup

func main() {   
    wg.Add(1)
    c := make(chan int)
    go readFromChannel(c, time.After(time.Duration(2)*time.Second))
    time.Sleep(time.Duration(5) * time.Second)
    c <- 10
    wg.Wait()
}

func readFromChannel(c chan int, ti <-chan time.Time) {
    select {
    case x := <-c:
        fmt.Println("Read", x)
    case <-ti:
        fmt.Println("TIMED OUT")
    }
    wg.Done()
}

Answer 1

You have an unbuffered channel. According to the docs:

If the channel is unbuffered, the sender blocks until the receiver has received the value. If the channel has a buffer, the sender blocks only until the value has been copied to the buffer

By changing the channel to being buffered, we can avoid deadlock.

c := make(chan int, 10) // holds 10 ints

I also suggest reading https://golang.org/doc/effective_go.html#channels, it's got some good stuff in there related to channels.