Mercurial > cpython-lru_cache-weakref
diff Lib/Queue.py @ 52184:e4d9844aba25 legacy-trunk
Move the previously local import of threading to module level.
This is cleaner and avoids lockups in obscure cases where a Queue
is instantiated while the import lock is already held by another thread.
OKed by Tim Peters.
| author | Georg Brandl <georg@python.org> |
|---|---|
| date | Sun, 15 Mar 2009 22:11:07 +0000 |
| parents | c349f9fbc704 |
| children | b36cb4602e21 |
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--- a/Lib/Queue.py Sun Mar 15 21:59:37 2009 +0000 +++ b/Lib/Queue.py Sun Mar 15 22:11:07 2009 +0000 @@ -1,6 +1,10 @@ """A multi-producer, multi-consumer queue.""" from time import time as _time +try: + import threading as _threading +except ImportError: + import dummy_threading as _threading from collections import deque import heapq @@ -20,26 +24,22 @@ If maxsize is <= 0, the queue size is infinite. """ def __init__(self, maxsize=0): - try: - import threading - except ImportError: - import dummy_threading as threading self.maxsize = maxsize self._init(maxsize) # mutex must be held whenever the queue is mutating. All methods # that acquire mutex must release it before returning. mutex # is shared between the three conditions, so acquiring and # releasing the conditions also acquires and releases mutex. - self.mutex = threading.Lock() + self.mutex = _threading.Lock() # Notify not_empty whenever an item is added to the queue; a # thread waiting to get is notified then. - self.not_empty = threading.Condition(self.mutex) + self.not_empty = _threading.Condition(self.mutex) # Notify not_full whenever an item is removed from the queue; # a thread waiting to put is notified then. - self.not_full = threading.Condition(self.mutex) + self.not_full = _threading.Condition(self.mutex) # Notify all_tasks_done whenever the number of unfinished tasks # drops to zero; thread waiting to join() is notified to resume - self.all_tasks_done = threading.Condition(self.mutex) + self.all_tasks_done = _threading.Condition(self.mutex) self.unfinished_tasks = 0 def task_done(self):
