source: python/trunk/Lib/threading.py@ 380

Last change on this file since 380 was 2, checked in by Yuri Dario, 15 years ago

Initial import for vendor code.

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1"""Thread module emulating a subset of Java's threading model."""
2
3import sys as _sys
4
5try:
6 import thread
7except ImportError:
8 del _sys.modules[__name__]
9 raise
10
11import warnings
12
13from functools import wraps
14from time import time as _time, sleep as _sleep
15from traceback import format_exc as _format_exc
16from collections import deque
17
18# Note regarding PEP 8 compliant aliases
19# This threading model was originally inspired by Java, and inherited
20# the convention of camelCase function and method names from that
21# language. While those names are not in any imminent danger of being
22# deprecated, starting with Python 2.6, the module now provides a
23# PEP 8 compliant alias for any such method name.
24# Using the new PEP 8 compliant names also facilitates substitution
25# with the multiprocessing module, which doesn't provide the old
26# Java inspired names.
27
28
29# Rename some stuff so "from threading import *" is safe
30__all__ = ['activeCount', 'active_count', 'Condition', 'currentThread',
31 'current_thread', 'enumerate', 'Event',
32 'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore', 'Thread',
33 'Timer', 'setprofile', 'settrace', 'local', 'stack_size']
34
35_start_new_thread = thread.start_new_thread
36_allocate_lock = thread.allocate_lock
37_get_ident = thread.get_ident
38ThreadError = thread.error
39del thread
40
41
42# sys.exc_clear is used to work around the fact that except blocks
43# don't fully clear the exception until 3.0.
44warnings.filterwarnings('ignore', category=DeprecationWarning,
45 module='threading', message='sys.exc_clear')
46
47# Debug support (adapted from ihooks.py).
48# All the major classes here derive from _Verbose. We force that to
49# be a new-style class so that all the major classes here are new-style.
50# This helps debugging (type(instance) is more revealing for instances
51# of new-style classes).
52
53_VERBOSE = False
54
55if __debug__:
56
57 class _Verbose(object):
58
59 def __init__(self, verbose=None):
60 if verbose is None:
61 verbose = _VERBOSE
62 self.__verbose = verbose
63
64 def _note(self, format, *args):
65 if self.__verbose:
66 format = format % args
67 format = "%s: %s\n" % (
68 current_thread().name, format)
69 _sys.stderr.write(format)
70
71else:
72 # Disable this when using "python -O"
73 class _Verbose(object):
74 def __init__(self, verbose=None):
75 pass
76 def _note(self, *args):
77 pass
78
79# Support for profile and trace hooks
80
81_profile_hook = None
82_trace_hook = None
83
84def setprofile(func):
85 global _profile_hook
86 _profile_hook = func
87
88def settrace(func):
89 global _trace_hook
90 _trace_hook = func
91
92# Synchronization classes
93
94Lock = _allocate_lock
95
96def RLock(*args, **kwargs):
97 return _RLock(*args, **kwargs)
98
99class _RLock(_Verbose):
100
101 def __init__(self, verbose=None):
102 _Verbose.__init__(self, verbose)
103 self.__block = _allocate_lock()
104 self.__owner = None
105 self.__count = 0
106
107 def __repr__(self):
108 owner = self.__owner
109 try:
110 owner = _active[owner].name
111 except KeyError:
112 pass
113 return "<%s owner=%r count=%d>" % (
114 self.__class__.__name__, owner, self.__count)
115
116 def acquire(self, blocking=1):
117 me = _get_ident()
118 if self.__owner == me:
119 self.__count = self.__count + 1
120 if __debug__:
121 self._note("%s.acquire(%s): recursive success", self, blocking)
122 return 1
123 rc = self.__block.acquire(blocking)
124 if rc:
125 self.__owner = me
126 self.__count = 1
127 if __debug__:
128 self._note("%s.acquire(%s): initial success", self, blocking)
129 else:
130 if __debug__:
131 self._note("%s.acquire(%s): failure", self, blocking)
132 return rc
133
134 __enter__ = acquire
135
136 def release(self):
137 if self.__owner != _get_ident():
138 raise RuntimeError("cannot release un-acquired lock")
139 self.__count = count = self.__count - 1
140 if not count:
141 self.__owner = None
142 self.__block.release()
143 if __debug__:
144 self._note("%s.release(): final release", self)
145 else:
146 if __debug__:
147 self._note("%s.release(): non-final release", self)
148
149 def __exit__(self, t, v, tb):
150 self.release()
151
152 # Internal methods used by condition variables
153
154 def _acquire_restore(self, count_owner):
155 count, owner = count_owner
156 self.__block.acquire()
157 self.__count = count
158 self.__owner = owner
159 if __debug__:
160 self._note("%s._acquire_restore()", self)
161
162 def _release_save(self):
163 if __debug__:
164 self._note("%s._release_save()", self)
165 count = self.__count
166 self.__count = 0
167 owner = self.__owner
168 self.__owner = None
169 self.__block.release()
170 return (count, owner)
171
172 def _is_owned(self):
173 return self.__owner == _get_ident()
174
175
176def Condition(*args, **kwargs):
177 return _Condition(*args, **kwargs)
178
179class _Condition(_Verbose):
180
181 def __init__(self, lock=None, verbose=None):
182 _Verbose.__init__(self, verbose)
183 if lock is None:
184 lock = RLock()
185 self.__lock = lock
186 # Export the lock's acquire() and release() methods
187 self.acquire = lock.acquire
188 self.release = lock.release
189 # If the lock defines _release_save() and/or _acquire_restore(),
190 # these override the default implementations (which just call
191 # release() and acquire() on the lock). Ditto for _is_owned().
192 try:
193 self._release_save = lock._release_save
194 except AttributeError:
195 pass
196 try:
197 self._acquire_restore = lock._acquire_restore
198 except AttributeError:
199 pass
200 try:
201 self._is_owned = lock._is_owned
202 except AttributeError:
203 pass
204 self.__waiters = []
205
206 def __enter__(self):
207 return self.__lock.__enter__()
208
209 def __exit__(self, *args):
210 return self.__lock.__exit__(*args)
211
212 def __repr__(self):
213 return "<Condition(%s, %d)>" % (self.__lock, len(self.__waiters))
214
215 def _release_save(self):
216 self.__lock.release() # No state to save
217
218 def _acquire_restore(self, x):
219 self.__lock.acquire() # Ignore saved state
220
221 def _is_owned(self):
222 # Return True if lock is owned by current_thread.
223 # This method is called only if __lock doesn't have _is_owned().
224 if self.__lock.acquire(0):
225 self.__lock.release()
226 return False
227 else:
228 return True
229
230 def wait(self, timeout=None):
231 if not self._is_owned():
232 raise RuntimeError("cannot wait on un-acquired lock")
233 waiter = _allocate_lock()
234 waiter.acquire()
235 self.__waiters.append(waiter)
236 saved_state = self._release_save()
237 try: # restore state no matter what (e.g., KeyboardInterrupt)
238 if timeout is None:
239 waiter.acquire()
240 if __debug__:
241 self._note("%s.wait(): got it", self)
242 else:
243 # Balancing act: We can't afford a pure busy loop, so we
244 # have to sleep; but if we sleep the whole timeout time,
245 # we'll be unresponsive. The scheme here sleeps very
246 # little at first, longer as time goes on, but never longer
247 # than 20 times per second (or the timeout time remaining).
248 endtime = _time() + timeout
249 delay = 0.0005 # 500 us -> initial delay of 1 ms
250 while True:
251 gotit = waiter.acquire(0)
252 if gotit:
253 break
254 remaining = endtime - _time()
255 if remaining <= 0:
256 break
257 delay = min(delay * 2, remaining, .05)
258 _sleep(delay)
259 if not gotit:
260 if __debug__:
261 self._note("%s.wait(%s): timed out", self, timeout)
262 try:
263 self.__waiters.remove(waiter)
264 except ValueError:
265 pass
266 else:
267 if __debug__:
268 self._note("%s.wait(%s): got it", self, timeout)
269 finally:
270 self._acquire_restore(saved_state)
271
272 def notify(self, n=1):
273 if not self._is_owned():
274 raise RuntimeError("cannot notify on un-acquired lock")
275 __waiters = self.__waiters
276 waiters = __waiters[:n]
277 if not waiters:
278 if __debug__:
279 self._note("%s.notify(): no waiters", self)
280 return
281 self._note("%s.notify(): notifying %d waiter%s", self, n,
282 n!=1 and "s" or "")
283 for waiter in waiters:
284 waiter.release()
285 try:
286 __waiters.remove(waiter)
287 except ValueError:
288 pass
289
290 def notifyAll(self):
291 self.notify(len(self.__waiters))
292
293 notify_all = notifyAll
294
295
296def Semaphore(*args, **kwargs):
297 return _Semaphore(*args, **kwargs)
298
299class _Semaphore(_Verbose):
300
301 # After Tim Peters' semaphore class, but not quite the same (no maximum)
302
303 def __init__(self, value=1, verbose=None):
304 if value < 0:
305 raise ValueError("semaphore initial value must be >= 0")
306 _Verbose.__init__(self, verbose)
307 self.__cond = Condition(Lock())
308 self.__value = value
309
310 def acquire(self, blocking=1):
311 rc = False
312 self.__cond.acquire()
313 while self.__value == 0:
314 if not blocking:
315 break
316 if __debug__:
317 self._note("%s.acquire(%s): blocked waiting, value=%s",
318 self, blocking, self.__value)
319 self.__cond.wait()
320 else:
321 self.__value = self.__value - 1
322 if __debug__:
323 self._note("%s.acquire: success, value=%s",
324 self, self.__value)
325 rc = True
326 self.__cond.release()
327 return rc
328
329 __enter__ = acquire
330
331 def release(self):
332 self.__cond.acquire()
333 self.__value = self.__value + 1
334 if __debug__:
335 self._note("%s.release: success, value=%s",
336 self, self.__value)
337 self.__cond.notify()
338 self.__cond.release()
339
340 def __exit__(self, t, v, tb):
341 self.release()
342
343
344def BoundedSemaphore(*args, **kwargs):
345 return _BoundedSemaphore(*args, **kwargs)
346
347class _BoundedSemaphore(_Semaphore):
348 """Semaphore that checks that # releases is <= # acquires"""
349 def __init__(self, value=1, verbose=None):
350 _Semaphore.__init__(self, value, verbose)
351 self._initial_value = value
352
353 def release(self):
354 if self._Semaphore__value >= self._initial_value:
355 raise ValueError, "Semaphore released too many times"
356 return _Semaphore.release(self)
357
358
359def Event(*args, **kwargs):
360 return _Event(*args, **kwargs)
361
362class _Event(_Verbose):
363
364 # After Tim Peters' event class (without is_posted())
365
366 def __init__(self, verbose=None):
367 _Verbose.__init__(self, verbose)
368 self.__cond = Condition(Lock())
369 self.__flag = False
370
371 def isSet(self):
372 return self.__flag
373
374 is_set = isSet
375
376 def set(self):
377 self.__cond.acquire()
378 try:
379 self.__flag = True
380 self.__cond.notify_all()
381 finally:
382 self.__cond.release()
383
384 def clear(self):
385 self.__cond.acquire()
386 try:
387 self.__flag = False
388 finally:
389 self.__cond.release()
390
391 def wait(self, timeout=None):
392 self.__cond.acquire()
393 try:
394 if not self.__flag:
395 self.__cond.wait(timeout)
396 finally:
397 self.__cond.release()
398
399# Helper to generate new thread names
400_counter = 0
401def _newname(template="Thread-%d"):
402 global _counter
403 _counter = _counter + 1
404 return template % _counter
405
406# Active thread administration
407_active_limbo_lock = _allocate_lock()
408_active = {} # maps thread id to Thread object
409_limbo = {}
410
411
412# Main class for threads
413
414class Thread(_Verbose):
415
416 __initialized = False
417 # Need to store a reference to sys.exc_info for printing
418 # out exceptions when a thread tries to use a global var. during interp.
419 # shutdown and thus raises an exception about trying to perform some
420 # operation on/with a NoneType
421 __exc_info = _sys.exc_info
422 # Keep sys.exc_clear too to clear the exception just before
423 # allowing .join() to return.
424 __exc_clear = _sys.exc_clear
425
426 def __init__(self, group=None, target=None, name=None,
427 args=(), kwargs=None, verbose=None):
428 assert group is None, "group argument must be None for now"
429 _Verbose.__init__(self, verbose)
430 if kwargs is None:
431 kwargs = {}
432 self.__target = target
433 self.__name = str(name or _newname())
434 self.__args = args
435 self.__kwargs = kwargs
436 self.__daemonic = self._set_daemon()
437 self.__ident = None
438 self.__started = Event()
439 self.__stopped = False
440 self.__block = Condition(Lock())
441 self.__initialized = True
442 # sys.stderr is not stored in the class like
443 # sys.exc_info since it can be changed between instances
444 self.__stderr = _sys.stderr
445
446 def _set_daemon(self):
447 # Overridden in _MainThread and _DummyThread
448 return current_thread().daemon
449
450 def __repr__(self):
451 assert self.__initialized, "Thread.__init__() was not called"
452 status = "initial"
453 if self.__started.is_set():
454 status = "started"
455 if self.__stopped:
456 status = "stopped"
457 if self.__daemonic:
458 status += " daemon"
459 if self.__ident is not None:
460 status += " %s" % self.__ident
461 return "<%s(%s, %s)>" % (self.__class__.__name__, self.__name, status)
462
463 def start(self):
464 if not self.__initialized:
465 raise RuntimeError("thread.__init__() not called")
466 if self.__started.is_set():
467 raise RuntimeError("thread already started")
468 if __debug__:
469 self._note("%s.start(): starting thread", self)
470 _active_limbo_lock.acquire()
471 _limbo[self] = self
472 _active_limbo_lock.release()
473 try:
474 _start_new_thread(self.__bootstrap, ())
475 except Exception:
476 with _active_limbo_lock:
477 del _limbo[self]
478 raise
479 self.__started.wait()
480
481 def run(self):
482 try:
483 if self.__target:
484 self.__target(*self.__args, **self.__kwargs)
485 finally:
486 # Avoid a refcycle if the thread is running a function with
487 # an argument that has a member that points to the thread.
488 del self.__target, self.__args, self.__kwargs
489
490 def __bootstrap(self):
491 # Wrapper around the real bootstrap code that ignores
492 # exceptions during interpreter cleanup. Those typically
493 # happen when a daemon thread wakes up at an unfortunate
494 # moment, finds the world around it destroyed, and raises some
495 # random exception *** while trying to report the exception in
496 # __bootstrap_inner() below ***. Those random exceptions
497 # don't help anybody, and they confuse users, so we suppress
498 # them. We suppress them only when it appears that the world
499 # indeed has already been destroyed, so that exceptions in
500 # __bootstrap_inner() during normal business hours are properly
501 # reported. Also, we only suppress them for daemonic threads;
502 # if a non-daemonic encounters this, something else is wrong.
503 try:
504 self.__bootstrap_inner()
505 except:
506 if self.__daemonic and _sys is None:
507 return
508 raise
509
510 def _set_ident(self):
511 self.__ident = _get_ident()
512
513 def __bootstrap_inner(self):
514 try:
515 self._set_ident()
516 self.__started.set()
517 _active_limbo_lock.acquire()
518 _active[self.__ident] = self
519 del _limbo[self]
520 _active_limbo_lock.release()
521 if __debug__:
522 self._note("%s.__bootstrap(): thread started", self)
523
524 if _trace_hook:
525 self._note("%s.__bootstrap(): registering trace hook", self)
526 _sys.settrace(_trace_hook)
527 if _profile_hook:
528 self._note("%s.__bootstrap(): registering profile hook", self)
529 _sys.setprofile(_profile_hook)
530
531 try:
532 self.run()
533 except SystemExit:
534 if __debug__:
535 self._note("%s.__bootstrap(): raised SystemExit", self)
536 except:
537 if __debug__:
538 self._note("%s.__bootstrap(): unhandled exception", self)
539 # If sys.stderr is no more (most likely from interpreter
540 # shutdown) use self.__stderr. Otherwise still use sys (as in
541 # _sys) in case sys.stderr was redefined since the creation of
542 # self.
543 if _sys:
544 _sys.stderr.write("Exception in thread %s:\n%s\n" %
545 (self.name, _format_exc()))
546 else:
547 # Do the best job possible w/o a huge amt. of code to
548 # approximate a traceback (code ideas from
549 # Lib/traceback.py)
550 exc_type, exc_value, exc_tb = self.__exc_info()
551 try:
552 print>>self.__stderr, (
553 "Exception in thread " + self.name +
554 " (most likely raised during interpreter shutdown):")
555 print>>self.__stderr, (
556 "Traceback (most recent call last):")
557 while exc_tb:
558 print>>self.__stderr, (
559 ' File "%s", line %s, in %s' %
560 (exc_tb.tb_frame.f_code.co_filename,
561 exc_tb.tb_lineno,
562 exc_tb.tb_frame.f_code.co_name))
563 exc_tb = exc_tb.tb_next
564 print>>self.__stderr, ("%s: %s" % (exc_type, exc_value))
565 # Make sure that exc_tb gets deleted since it is a memory
566 # hog; deleting everything else is just for thoroughness
567 finally:
568 del exc_type, exc_value, exc_tb
569 else:
570 if __debug__:
571 self._note("%s.__bootstrap(): normal return", self)
572 finally:
573 # Prevent a race in
574 # test_threading.test_no_refcycle_through_target when
575 # the exception keeps the target alive past when we
576 # assert that it's dead.
577 self.__exc_clear()
578 finally:
579 with _active_limbo_lock:
580 self.__stop()
581 try:
582 # We don't call self.__delete() because it also
583 # grabs _active_limbo_lock.
584 del _active[_get_ident()]
585 except:
586 pass
587
588 def __stop(self):
589 self.__block.acquire()
590 self.__stopped = True
591 self.__block.notify_all()
592 self.__block.release()
593
594 def __delete(self):
595 "Remove current thread from the dict of currently running threads."
596
597 # Notes about running with dummy_thread:
598 #
599 # Must take care to not raise an exception if dummy_thread is being
600 # used (and thus this module is being used as an instance of
601 # dummy_threading). dummy_thread.get_ident() always returns -1 since
602 # there is only one thread if dummy_thread is being used. Thus
603 # len(_active) is always <= 1 here, and any Thread instance created
604 # overwrites the (if any) thread currently registered in _active.
605 #
606 # An instance of _MainThread is always created by 'threading'. This
607 # gets overwritten the instant an instance of Thread is created; both
608 # threads return -1 from dummy_thread.get_ident() and thus have the
609 # same key in the dict. So when the _MainThread instance created by
610 # 'threading' tries to clean itself up when atexit calls this method
611 # it gets a KeyError if another Thread instance was created.
612 #
613 # This all means that KeyError from trying to delete something from
614 # _active if dummy_threading is being used is a red herring. But
615 # since it isn't if dummy_threading is *not* being used then don't
616 # hide the exception.
617
618 try:
619 with _active_limbo_lock:
620 del _active[_get_ident()]
621 # There must not be any python code between the previous line
622 # and after the lock is released. Otherwise a tracing function
623 # could try to acquire the lock again in the same thread, (in
624 # current_thread()), and would block.
625 except KeyError:
626 if 'dummy_threading' not in _sys.modules:
627 raise
628
629 def join(self, timeout=None):
630 if not self.__initialized:
631 raise RuntimeError("Thread.__init__() not called")
632 if not self.__started.is_set():
633 raise RuntimeError("cannot join thread before it is started")
634 if self is current_thread():
635 raise RuntimeError("cannot join current thread")
636
637 if __debug__:
638 if not self.__stopped:
639 self._note("%s.join(): waiting until thread stops", self)
640 self.__block.acquire()
641 try:
642 if timeout is None:
643 while not self.__stopped:
644 self.__block.wait()
645 if __debug__:
646 self._note("%s.join(): thread stopped", self)
647 else:
648 deadline = _time() + timeout
649 while not self.__stopped:
650 delay = deadline - _time()
651 if delay <= 0:
652 if __debug__:
653 self._note("%s.join(): timed out", self)
654 break
655 self.__block.wait(delay)
656 else:
657 if __debug__:
658 self._note("%s.join(): thread stopped", self)
659 finally:
660 self.__block.release()
661
662 @property
663 def name(self):
664 assert self.__initialized, "Thread.__init__() not called"
665 return self.__name
666
667 @name.setter
668 def name(self, name):
669 assert self.__initialized, "Thread.__init__() not called"
670 self.__name = str(name)
671
672 @property
673 def ident(self):
674 assert self.__initialized, "Thread.__init__() not called"
675 return self.__ident
676
677 def isAlive(self):
678 assert self.__initialized, "Thread.__init__() not called"
679 return self.__started.is_set() and not self.__stopped
680
681 is_alive = isAlive
682
683 @property
684 def daemon(self):
685 assert self.__initialized, "Thread.__init__() not called"
686 return self.__daemonic
687
688 @daemon.setter
689 def daemon(self, daemonic):
690 if not self.__initialized:
691 raise RuntimeError("Thread.__init__() not called")
692 if self.__started.is_set():
693 raise RuntimeError("cannot set daemon status of active thread");
694 self.__daemonic = daemonic
695
696 def isDaemon(self):
697 return self.daemon
698
699 def setDaemon(self, daemonic):
700 self.daemon = daemonic
701
702 def getName(self):
703 return self.name
704
705 def setName(self, name):
706 self.name = name
707
708# The timer class was contributed by Itamar Shtull-Trauring
709
710def Timer(*args, **kwargs):
711 return _Timer(*args, **kwargs)
712
713class _Timer(Thread):
714 """Call a function after a specified number of seconds:
715
716 t = Timer(30.0, f, args=[], kwargs={})
717 t.start()
718 t.cancel() # stop the timer's action if it's still waiting
719 """
720
721 def __init__(self, interval, function, args=[], kwargs={}):
722 Thread.__init__(self)
723 self.interval = interval
724 self.function = function
725 self.args = args
726 self.kwargs = kwargs
727 self.finished = Event()
728
729 def cancel(self):
730 """Stop the timer if it hasn't finished yet"""
731 self.finished.set()
732
733 def run(self):
734 self.finished.wait(self.interval)
735 if not self.finished.is_set():
736 self.function(*self.args, **self.kwargs)
737 self.finished.set()
738
739# Special thread class to represent the main thread
740# This is garbage collected through an exit handler
741
742class _MainThread(Thread):
743
744 def __init__(self):
745 Thread.__init__(self, name="MainThread")
746 self._Thread__started.set()
747 self._set_ident()
748 _active_limbo_lock.acquire()
749 _active[_get_ident()] = self
750 _active_limbo_lock.release()
751
752 def _set_daemon(self):
753 return False
754
755 def _exitfunc(self):
756 self._Thread__stop()
757 t = _pickSomeNonDaemonThread()
758 if t:
759 if __debug__:
760 self._note("%s: waiting for other threads", self)
761 while t:
762 t.join()
763 t = _pickSomeNonDaemonThread()
764 if __debug__:
765 self._note("%s: exiting", self)
766 self._Thread__delete()
767
768def _pickSomeNonDaemonThread():
769 for t in enumerate():
770 if not t.daemon and t.is_alive():
771 return t
772 return None
773
774
775# Dummy thread class to represent threads not started here.
776# These aren't garbage collected when they die, nor can they be waited for.
777# If they invoke anything in threading.py that calls current_thread(), they
778# leave an entry in the _active dict forever after.
779# Their purpose is to return *something* from current_thread().
780# They are marked as daemon threads so we won't wait for them
781# when we exit (conform previous semantics).
782
783class _DummyThread(Thread):
784
785 def __init__(self):
786 Thread.__init__(self, name=_newname("Dummy-%d"))
787
788 # Thread.__block consumes an OS-level locking primitive, which
789 # can never be used by a _DummyThread. Since a _DummyThread
790 # instance is immortal, that's bad, so release this resource.
791 del self._Thread__block
792
793 self._Thread__started.set()
794 self._set_ident()
795 _active_limbo_lock.acquire()
796 _active[_get_ident()] = self
797 _active_limbo_lock.release()
798
799 def _set_daemon(self):
800 return True
801
802 def join(self, timeout=None):
803 assert False, "cannot join a dummy thread"
804
805
806# Global API functions
807
808def currentThread():
809 try:
810 return _active[_get_ident()]
811 except KeyError:
812 ##print "current_thread(): no current thread for", _get_ident()
813 return _DummyThread()
814
815current_thread = currentThread
816
817def activeCount():
818 _active_limbo_lock.acquire()
819 count = len(_active) + len(_limbo)
820 _active_limbo_lock.release()
821 return count
822
823active_count = activeCount
824
825def _enumerate():
826 # Same as enumerate(), but without the lock. Internal use only.
827 return _active.values() + _limbo.values()
828
829def enumerate():
830 _active_limbo_lock.acquire()
831 active = _active.values() + _limbo.values()
832 _active_limbo_lock.release()
833 return active
834
835from thread import stack_size
836
837# Create the main thread object,
838# and make it available for the interpreter
839# (Py_Main) as threading._shutdown.
840
841_shutdown = _MainThread()._exitfunc
842
843# get thread-local implementation, either from the thread
844# module, or from the python fallback
845
846try:
847 from thread import _local as local
848except ImportError:
849 from _threading_local import local
850
851
852def _after_fork():
853 # This function is called by Python/ceval.c:PyEval_ReInitThreads which
854 # is called from PyOS_AfterFork. Here we cleanup threading module state
855 # that should not exist after a fork.
856
857 # Reset _active_limbo_lock, in case we forked while the lock was held
858 # by another (non-forked) thread. http://bugs.python.org/issue874900
859 global _active_limbo_lock
860 _active_limbo_lock = _allocate_lock()
861
862 # fork() only copied the current thread; clear references to others.
863 new_active = {}
864 current = current_thread()
865 with _active_limbo_lock:
866 for thread in _active.itervalues():
867 if thread is current:
868 # There is only one active thread. We reset the ident to
869 # its new value since it can have changed.
870 ident = _get_ident()
871 thread._Thread__ident = ident
872 new_active[ident] = thread
873 else:
874 # All the others are already stopped.
875 # We don't call _Thread__stop() because it tries to acquire
876 # thread._Thread__block which could also have been held while
877 # we forked.
878 thread._Thread__stopped = True
879
880 _limbo.clear()
881 _active.clear()
882 _active.update(new_active)
883 assert len(_active) == 1
884
885
886# Self-test code
887
888def _test():
889
890 class BoundedQueue(_Verbose):
891
892 def __init__(self, limit):
893 _Verbose.__init__(self)
894 self.mon = RLock()
895 self.rc = Condition(self.mon)
896 self.wc = Condition(self.mon)
897 self.limit = limit
898 self.queue = deque()
899
900 def put(self, item):
901 self.mon.acquire()
902 while len(self.queue) >= self.limit:
903 self._note("put(%s): queue full", item)
904 self.wc.wait()
905 self.queue.append(item)
906 self._note("put(%s): appended, length now %d",
907 item, len(self.queue))
908 self.rc.notify()
909 self.mon.release()
910
911 def get(self):
912 self.mon.acquire()
913 while not self.queue:
914 self._note("get(): queue empty")
915 self.rc.wait()
916 item = self.queue.popleft()
917 self._note("get(): got %s, %d left", item, len(self.queue))
918 self.wc.notify()
919 self.mon.release()
920 return item
921
922 class ProducerThread(Thread):
923
924 def __init__(self, queue, quota):
925 Thread.__init__(self, name="Producer")
926 self.queue = queue
927 self.quota = quota
928
929 def run(self):
930 from random import random
931 counter = 0
932 while counter < self.quota:
933 counter = counter + 1
934 self.queue.put("%s.%d" % (self.name, counter))
935 _sleep(random() * 0.00001)
936
937
938 class ConsumerThread(Thread):
939
940 def __init__(self, queue, count):
941 Thread.__init__(self, name="Consumer")
942 self.queue = queue
943 self.count = count
944
945 def run(self):
946 while self.count > 0:
947 item = self.queue.get()
948 print item
949 self.count = self.count - 1
950
951 NP = 3
952 QL = 4
953 NI = 5
954
955 Q = BoundedQueue(QL)
956 P = []
957 for i in range(NP):
958 t = ProducerThread(Q, NI)
959 t.name = ("Producer-%d" % (i+1))
960 P.append(t)
961 C = ConsumerThread(Q, NI*NP)
962 for t in P:
963 t.start()
964 _sleep(0.000001)
965 C.start()
966 for t in P:
967 t.join()
968 C.join()
969
970if __name__ == '__main__':
971 _test()
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