通过渠道和goroutines增值1000倍

发布于10月16日

我需要通过创建x0个Goroutine来增加x个x0倍，这将通过通道增加x个.我该怎么做呢？

package main

import (
    "fmt"
)

func main() {
    var ch = make(chan int)

    //1000 goroutines sending 1 through a channel
    var x = 0
    for i := 0; i < 1000; i++ {
        go func() {
            ch <- 1
        }()
    }

    //Here i need to increase x by value read from the channel and then stop when the last value was sent
    //But this code doesn't work
    for {
        if v, ok := <-ch; ok {
            x += v
        } else {
            break
        }
    }

    fmt.Println(x)
}

我想在最后关闭通道，但我不知道如何检测最后一个值是什么时候发送的

推荐答案

sync.WaitGroup可用于检测一组Goroutine的完成情况.例如:

package main

import (
    "fmt"
    "sync"
)

func main() {
    var ch = make(chan int)
    wg := &sync.WaitGroup{}

    //1000 goroutines sending 1 through a channel
    var x = 0
    for i := 0; i < 1000; i++ {
        wg.Add(1)
        go func() {
            defer wg.Done()
            ch <- 1
        }()
    }

    go func() {
        wg.Wait()
        close(ch)
    }()

    //Here i need to increase x by value read from the channel and then stop when the last value was sent
    //But this code doesn't work
    for {
        if v, ok := <-ch; ok {
            x += v
        } else {
            break
        }
    }

    fmt.Println(x)
}