Python多重處理流程：使用Manager Queue時延遲識別事件

Question

我有以下代碼：

from multiprocessing import Process, Manager, Event

manager = Manager()
shared_Queue = manager.Queue(10)
ev = Event()

def do_this(shared_queue, ev):
    while not ev.is_set():
        if not shared_Queue.__getattribute__('empty')():
           item = shared_queue.get()
           print item
    print 'released!'

subprocs = []
for i in xrange(10):
    subproc = Process(target=do_this, args=(shared_Queue, ev, ))
    subprocs.append(subproc)
    subproc.start()

現在，如果我運行此命令，請問這些過程是否仍然有效：

for subproc in subprocs: print subproc.is_alive()

當然，我得到了所有的真理。

經過以下操作：*如果我不執行這些操作就沒有錯誤！

shared_Queue.put(3)
shared_Queue.put(5)

現在，我想設置事件使用以下命令殺死所有事件：

ev.set()

但隨后卻看不到“已發行！” 10次​​后，我得到的這些打印數量不等，大約2到5秒后，我收到了很多錯誤：

released!
released!
released!
released!
released!
released!
released!
Process Process-10:
Traceback (most recent call last):
  File 
 "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/
multiprocessing/process.py", line 258, in _bootstrap
    self.run()
  File 
"/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/
multiprocessing/process.py", line 114, in run
    self._target(*self._args, **self._kwargs)
  File "<input>", line 10, in do_this
  File "<string>", line 2, in get
  File 
"/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/
multiprocessing/managers.py", line 759, in _callmethod
    kind, result = conn.recv()
EOFError
Process Process-5:
Traceback (most recent call last):
  File 
"/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/
multiprocessing/process.py", line 258, in _bootstrap
    self.run()
  File 
"/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/
multiprocessing/process.py", line 114, in run
    self._target(*self._args, **self._kwargs)
  File "<input>", line 10, in do_this
  File "<string>", line 2, in get
  File 
"/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/
multiprocessing/managers.py", line 759, in _callmethod
    kind, result = conn.recv()
EOFError
Process Process-7:
Traceback (most recent call last):
  File 
"/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/
multiprocessing/process.py", line 258, in _bootstrap
    self.run()
  File 
"/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/
multiprocessing/process.py", line 114, in run
    self._target(*self._args, **self._kwargs)
  File "<input>", line 10, in do_this
  File "<string>", line 2, in get
  File 
"/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/
multiprocessing/managers.py", line 759, in _callmethod
    kind, result = conn.recv()
EOFError

為什么某些進程無法識別事件集並在以后顯示為錯誤？ 有沒有更好的方法通知他們死亡？

Answer 1

感謝您的評論stovfl，您是對的，ev.set（）不會殺死我不小心使用的任何單詞。

對於我遇到的問題，我了解到多處理隊列是進程和線程安全的，這意味着，如果隊列已滿，則在將某些內容寫入隊列之前，我的進程將停止。

如果在某些進程仍在等待將某些內容寫入完整隊列時嘗試設置事件，則它們將無法識別事件集。

關鍵是清空所有Queue，讓進程對其進行寫操作，然后到達可以檢查事件的第一行！