python – 当使用futures.ProcessPoolExecutor而不是future.Thre

submissions = get_submissions(1)
with futures.ProcessPoolExecutor(max_workers=4) as executor:
#or using this: with futures.ThreadPoolExecutor(max_workers=4) as executor:
    for s in executor.map(map_func,submissions):
        collection_front.update({"time_recorded":time_recorded},{'$push':{"thread_list":s}},upsert=True)

它可以很好地/快速地使用线程,但是当我尝试使用进程时,我得到一个完整的队列并且出现此错误：

File "/usr/local/lib/python3.4/dist-packages/praw/objects.py",line 82,in __getattr__
    if not self.has_fetched:
RuntimeError: maximum recursion depth exceeded
Exception in thread Thread-3:
Traceback (most recent call last):
  File "/usr/lib/python3.4/threading.py",line 920,in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.4/threading.py",line 868,in run
    self._target(*self._args,**self._kwargs)
  File "/usr/lib/python3.4/concurrent/futures/process.py",line 251,in _queue_management_worker
    shutdown_worker()
  File "/usr/lib/python3.4/concurrent/futures/process.py",line 209,in shutdown_worker
    call_queue.put_nowait(None)
  File "/usr/lib/python3.4/multiprocessing/queues.py",line 131,in put_nowait
    return self.put(obj,False)
  File "/usr/lib/python3.4/multiprocessing/queues.py",in put
    raise Full
queue.Full

Traceback (most recent call last):
  File "reddit_proceses.py",line 64,in <module>
    for s in executor.map(map_func,submissions):
  File "/usr/lib/python3.4/concurrent/futures/_base.py",line 549,in result_iterator
    yield future.result()
  File "/usr/lib/python3.4/concurrent/futures/_base.py",line 402,in result
    return self.__get_result()
  File "/usr/lib/python3.4/concurrent/futures/_base.py",line 354,in __get_result
    raise self._exception
concurrent.futures.process.BrokenProcessPool: A process in the process pool was terminated abruptly while the future was running or pending.

请注意,最初这些过程对于小数据检索来说效果很好而且非常快,但现在它们根本不起作用.这是一个错误还是正在发生的事情,PRAW对象会导致进程的递归错误而不是Threads？