Python多重处理和太多打开的文件

Question

我在python中遇到多重处理问题。 在下面的代码中，我将调用7个worker（multiprocessing.Process）和一个结果threading.Thread。 在处理数据之前和之后（从文件中提取一些元数据），我运行：

lsof | grep ' <user> ' | grep 'python3'

我得到一些开放的句柄，如：

python3   17291              ivo  DEL       REG               0,20             5288943 /dev/shm/ZMcs2H
python3   17291              ivo  DEL       REG               0,20             5288942 /dev/shm/3iMR4q
python3   17291              ivo  DEL       REG               0,20             5288941 /dev/shm/XPYh79

当在循环中多次运行多重处理（处理一些连续的消息）时，我得到

OSError: [Errno 24] Too many open files

处理多处理程序包有什么问题吗？

def worker_process_results(meta_queue, res_dict):
    while True:
        try:
            (path, meta) = meta_queue.get()
            res_dict[path] = meta
        finally:
            meta_queue.task_done()

def multiprocess_get_metadata(paths, thread_count = 7):
    """ Scan files for metadata (multiprocessing). """
    file_queue = multiprocessing.JoinableQueue()
    meta_queue = multiprocessing.JoinableQueue()

    res_dict   = dict()
    # result thread    
    meta_thread = threading.Thread(target = lambda: worker_process_results(meta_queue, res_dict))
    meta_thread.daemon = True
    meta_thread.start()

    workers = []

    for _ in range(0, min(thread_count, len(paths))):
        worker = MetaDataWorker(file_queue, meta_queue)
        worker.daemon = True
        worker.start()        
        workers.append(worker)

    for path in paths:
        file_queue.put(path)

    file_queue.join()
    meta_queue.join()

    for x in workers:
        x.terminate()

    return res_dict

class MetaDataWorker(multiprocessing.Process):
    ''' Use library to get meta data from file. '''

    def __init__(self, file_queue, meta_queue):
        ''' Constructor. '''
        super().__init__()

        self.file_queue = file_queue
        self.meta_queue = meta_queue

    def run(self):
        """ Run. """

        while True:
            try:
                path = self.file_queue.get()
                meta = getmetadata(path)
                meta = None
                self.meta_queue.put((path, meta))
            except Exception as err:
                print("Thread end.")
                print("{0}".format(err))
            finally:
                self.file_queue.task_done()

Answer 1

已经解决了，我需要向工作人员发送一些结束信号，并且结果线程停止永无止境的循环