douxianglu4370 2014-01-08 21:47
浏览 53
已采纳

测试Go通道吞吐量-所有goroutine死锁

I made a small program to benchmark go channel throughput, however it always deadlocks, I tried very hard but cannot understand why:

package main

import (
    "fmt"
    "runtime"
)

const CONCURRENCY = 32
const WORK_PER_WORKER = 100
const TOTAL_WORK = CONCURRENCY * WORK_PER_WORKER

func work() {
    sum := 0
    for i := 0; i < 10000000; i++ {
        sum *= i
    }
}

type WorkItem struct {
    Done chan int
}

func main() {
    runtime.GOMAXPROCS(CONCURRENCY)
    var workQueue [CONCURRENCY]chan *WorkItem
    // initialize workers
    for i := 0; i < CONCURRENCY; i++ {
        workQueue[i] = make(chan *WorkItem)
    }
    // start workers
    for i := 0; i < CONCURRENCY; i++ {
        go func(i int) {
            anItem := <-workQueue[i]
            work()
            anItem.Done <- 1
        }(i)
    }
    completed := make(chan bool, TOTAL_WORK)
    for i := 0; i < TOTAL_WORK; i++ {
        go func(i int) {
            // send work to queues
            workToDo := &WorkItem{Done: make(chan int)}
            workQueue[i/WORK_PER_WORKER] <- workToDo // !! DEADLOCK
            // wait until the work is done
            <-workToDo.Done
            completed <- true
        }(i)
    }
    fmt.Println("Waiting")
    for i := 0; i < TOTAL_WORK; i++ {
        <-completed
    }
}
  • 写回答

2条回答 默认 最新

  • dongzhizhai4070 2014-01-08 23:22
    关注

    Your code go func(i int) { anItem := <-workQueue[i]; ... } removes juste 1 item from workQueue[i] but you are trying to stuff WORK_PER_WORKER items into it. You will work on CONCURRENCY many items and after that all reading goroutines have terminated and you have your deadlock.

    Looping in the worker goroutines "solves" your deadlock: http://play.golang.org/p/j2pavqnBDv Just "solves" because these worker goroutines will never terminate. Maybe you can experiment with closeing your channels to notify the worker goroutines when nothing will be sent.

    本回答被题主选为最佳回答 , 对您是否有帮助呢?
    评论
查看更多回答(1条)

报告相同问题?