英文:
How to receive data from multiple channels using for/select syntax?
问题
我有一个案例，需要在多个通道上接收数据，并且以某种方式退出无限的for循环。
这是一个简单的例子：
package mainimport ("fmt""sync""time")func main() {var wg sync.WaitGroupsumChannel := make(chan int)productChannel := make(chan int)for i := 1; i <= 5; i++ {wg.Add(1)go compute(i, sumChannel, productChannel, &wg)}go func() {wg.Wait()close(sumChannel)close(productChannel)}()for {select {case <-sumChannel:fmt.Println("sum")case <-productChannel:fmt.Println("prod")}}}func compute(i int, sumChannel chan int, productChannel chan int, wg *sync.WaitGroup) {time.Sleep(2 * time.Second)sumChannel <- i + iproductChannel <- i * iwg.Done()}
问题是我得到了一个无限的for循环。我知道我应该创建一个新的通道（例如quit）来退出循环。但是，我真的不明白在哪里放置quit信号，因为我不知道确切的位置可以确保所有的goroutine都已经完成。
英文:
I have case where I need to receive data on multiple channels and somehow quit infinite for loop.
Here is simple example:
package mainimport ("fmt""sync""time")func main() {var wg sync.WaitGroupsumChannel := make(chan int)productChannel := make(chan int)for i := 1; i <= 5; i++ {wg.Add(1)go compute(i, sumChannel, productChannel, &wg)}go func() {wg.Wait()close(sumChannel)close(productChannel)}()for {select {case <-sumChannel:fmt.Println("sum")case <-productChannel:fmt.Println("prod")}}}func compute(i int, sumChannel chan int, productChannel chan int, wg *sync.WaitGroup) {time.Sleep(2 * time.Second)sumChannel <- i + iproductChannel <- i * iwg.Done()}
The problem is I get infinite for loop. I know that I should create new channel (for instance,quit) for quitting from loop. But, I really don't understand where to put signal to quit, because I don't know exact place where I can be sure that all goroutines finished.
答案1
得分: 1
如果你在一个go routine中运行for循环，然后等待计算的go routines完成，你可以从那里取消循环：
package mainimport ("fmt""sync""time")func main() {var wg sync.WaitGroupsumChannel := make(chan int)productChannel := make(chan int)closeChannel := make(chan bool)for i := 1; i <= 5; i++ {wg.Add(1)go compute(i, sumChannel, productChannel, &wg)}go func() {loop:for {select {case <-sumChannel:fmt.Println("sum")case <-productChannel:fmt.Println("prod")case <-closeChannel:fmt.Println("break")break loop}}}()wg.Wait()closeChannel <- truefmt.Println("done")}func compute(i int, sumChannel chan int, productChannel chan int, wg *sync.WaitGroup) {time.Sleep(2 * time.Second)sumChannel <- i + iproductChannel <- i * iwg.Done()}
英文:
If you run the for loop in a go routine and then wait for the compute go routines to finish, you can cancel the loop from there:
package mainimport ("fmt""sync""time")func main() {var wg sync.WaitGroupsumChannel := make(chan int)productChannel := make(chan int)closeChannel := make(chan bool)for i := 1; i <= 5; i++ {wg.Add(1)go compute(i, sumChannel, productChannel, &wg)}go func() {loop:for {select {case <-sumChannel:fmt.Println("sum")case <-productChannel:fmt.Println("prod")case <-closeChannel:fmt.Println("break")break loop}}}()wg.Wait()closeChannel <- truefmt.Println("done")}func compute(i int, sumChannel chan int, productChannel chan int, wg *sync.WaitGroup) {time.Sleep(2 * time.Second)sumChannel <- i + iproductChannel <- i * iwg.Done()}
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