请教有关 Python 多进程 multiprocessing 中使用 Queue 产生的死锁问题 - V2EX
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mrning

请教有关 Python 多进程 multiprocessing 中使用 Queue 产生的死锁问题

  •  
  •   mrning Mar 26, 2021 3002 views
    This topic created in 1858 days ago, the information mentioned may be changed or developed.

    想实现多进程执行某项任务( moviepy 多进程),获得返回的值( frame,numpy 数组)。 尝过用 ApplyResult.get() 获取,不过返回的内容不能被 pickle,所以用了 queue 。 或者还有其他更好的方法么

    下面是个简单的 demo,似乎遇到了死锁,网上没有找到好的方案,求教

    import multiprocessing as mp from multiprocessing import Pool,Queue import os,time,random def worker(msg,q): t_start = time.time() print("%s Started with pid: %d"%(msg,os.getpid())) a = 2**100000000 t_stop = time.time() print(msg," Finishing with time: %0.2f"%(t_stop-t_start)) q.put(a) if __name__ == '__main__': mp.set_start_method("spawn") pool = mp.Pool(3) q=mp.Queue() for i in range(10): print(i) pool.apply_async(worker,(i,q,)) pool.close() for thread_i in range(10): result = q.get() print(result) pool.join() print("Waiting") 
    8 replies    2021-03-26 16:00:04 +08:00
    xiaolinjia
        1
    xiaolinjia  
       Mar 26, 2021   1
    q = mp.Manager().Queue()。个人经验是当你用 apply.async 卡住没抛出异常的时候,把他改成 apply 阻塞型,看是报啥错。
    nikan999
        2
    nikan999  
       Mar 26, 2021   1
    打印错误
    Queue objects should only be shared between processes through inheritance
    参考:
    https://stackoverflow.com/questions/9908781/sharing-a-result-queue-among-several-processes
    Jblue
        3
    Jblue  
       Mar 26, 2021
    可以把返回值存起来放到 redis 之类的
    mrning
        4
    mrning  
    OP
       Mar 26, 2021
    @xiaolinjia
    @nikan999
    改了下,在 linux 下执行,能看到 print 的信息了。worker 函数执行完了,然后在 result = q.get()这里卡住了


    @Jblue
    实在不行的话...也是个办法
    mrning
        5
    mrning  
    OP
       Mar 26, 2021
    ![py11.PNG]( https://i.loli.net/2021/03/26/qp5MS1olWGixHmA.png)

    代码及执行结果
    nikan999
        6
    nikan999  
       Mar 26, 2021
    print 2**100000000
    这个数太大了导致卡在打印这一块
    mrning
        7
    mrning  
    OP
       Mar 26, 2021
    @nikan999 原来如此

    /(ㄒoㄒ)/~~
    hareandlion
        8
    hareandlion  
       Mar 26, 2021 via Android
    queue 用 mp.Manager().Queue(),输出超级大数让我机器内存无法释放……
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