Question

我的例程下面列出了urllib2.Requests，并为每个请求生成一个新进程并将其触发。目的是为了异步速度，所以它都是一劳永逸（不需要响应）。问题是在下面的代码中生成的进程永远不会终止。所以经过其中几个盒子就可以了。上下文：Django Web应用程序。有什么帮助吗？

MP_CONCURRENT = int(multiprocessing.cpu_count()) * 2
if MP_CONCURRENT < 2: MP_CONCURRENT = 2
MPQ = multiprocessing.JoinableQueue(MP_CONCURRENT)



def request_manager(req_list):
    try:
            # put request list in the queue
            for req in req_list:
                    MPQ.put(req)

                    # call processes on queue
                    worker = multiprocessing.Process(target=process_request, args=(MPQ,))
                    worker.daemon = True
                    worker.start()

            # move on after queue is empty
            MPQ.join()

    except Exception, e:
            logging.error(traceback.print_exc())


# prcoess requests in queue
def process_request(MPQ):
    try:
            while True:
                    req = MPQ.get()
                    dr = urllib2.urlopen(req)
                    MPQ.task_done()

    except Exception, e:
            logging.error(traceback.print_exc())

Answer 1

也许我不对，但是

MP_CONCURRENT = int(multiprocessing.cpu_count()) * 2
if MP_CONCURRENT < 2: MP_CONCURRENT = 2
MPQ = multiprocessing.JoinableQueue(MP_CONCURRENT)



def request_manager(req_list):
    try:
            # put request list in the queue
            pool=[]
            for req in req_list:
                    MPQ.put(req)

                    # call processes on queue
                    worker = multiprocessing.Process(target=process_request, args=(MPQ,))
                    worker.daemon = True
                    worker.start()
                    pool.append(worker)

            # move on after queue is empty
            MPQ.join()
            # Close not needed processes
            for p in pool: p.terminate()

    except Exception, e:
            logging.error(traceback.print_exc())


# prcoess requests in queue
def process_request(MPQ):
    try:
            while True:
                    req = MPQ.get()
                    dr = urllib2.urlopen(req)
                    MPQ.task_done()

    except Exception, e:
            logging.error(traceback.print_exc())

Answer 2

MP_CONCURRENT = int(multiprocessing.cpu_count()) * 2
if MP_CONCURRENT < 2: MP_CONCURRENT = 2
MPQ = multiprocessing.JoinableQueue(MP_CONCURRENT)
CHUNK_SIZE = 20 #number of requests sended to one process.
pool = multiprocessing.Pool(MP_CONCURRENT)

def request_manager(req_list):
    try:
            # put request list in the queue
            responce=pool.map(process_request,req_list,CHUNK_SIZE) # function exits after all requests called and pool work ended
    # OR
            responce=pool.map_async(process_request,req_list,CHUNK_SIZE) #function request_manager exits after all requests passed to pool

    except Exception, e:
            logging.error(traceback.print_exc())


# prcoess requests in queue
def process_request(req):
    dr = urllib2.urlopen(req)

这比你的代码快〜5-10倍

Answer 3

将副“brocker”整合到django（例如rabbitmq或类似的东西）。

Answer 4

在一些摆弄（和睡个好觉）之后好吧，我相信我已经找到了问题（谢谢Eri，你是我需要的灵感）。僵尸进程的主要问题是我没有发出信号，说明这个过程已经完成（并且已经完成了），我（天真地）认为这两个进程都是自动进行多进程的。

有效的代码：

# function that will be run through the pool
def process_request(req):
    try:
            dr = urllib2.urlopen(req, timeout=30)

    except Exception, e:
            logging.error(traceback.print_exc())

# process killer
def sig_end(r):
    sys.exit()

# globals
MP_CONCURRENT = int(multiprocessing.cpu_count()) * 2
if MP_CONCURRENT < 2: MP_CONCURRENT = 2
CHUNK_SIZE = 20
POOL = multiprocessing.Pool(MP_CONCURRENT)    

# pool initiator
def request_manager(req_list):
    try:
            resp = POOL.map_async(process_request, req_list, CHUNK_SIZE, callback=sig_end)

    except Exception, e:
            logging.error(traceback.print_exc())

几点说明：

1）必须首先定义“map_async”（本例中为“process_request”）命中的函数（在全局声明之前）。

2）退出流程可能有更优雅的方式（建议欢迎）。

3）在这个例子中使用池确实是最好的（再次感谢Eri），因为“回调”功能允许我立即发出信号。

Python多进程进程永远不会终止

4 个答案: