blob: d96d99a713e90432155acdc1f9c8f08ff52e0f08 [file] [log] [blame]
Jeremy Hylton92bb6e72002-08-14 19:25:42 +00001"""Thread module emulating a subset of Java's threading model."""
Guido van Rossum7f5013a1998-04-09 22:01:42 +00002
Antoine Pitrou4a8bcdf2017-05-28 14:02:26 +02003import os as _os
Fred Drakea8725952002-12-30 23:32:50 +00004import sys as _sys
Georg Brandl2067bfd2008-05-25 13:05:15 +00005import _thread
Kyle Stanleyb61b8182020-03-27 15:31:22 -04006import functools
Fred Drakea8725952002-12-30 23:32:50 +00007
Victor Stinnerae586492014-09-02 23:18:25 +02008from time import monotonic as _time
Antoine Pitrouc081c0c2011-07-15 22:12:24 +02009from _weakrefset import WeakSet
R David Murrayb186f1df2014-10-04 17:43:54 -040010from itertools import islice as _islice, count as _count
Raymond Hettingerec4b1742013-03-10 17:57:28 -070011try:
Raymond Hettingerec4b1742013-03-10 17:57:28 -070012 from _collections import deque as _deque
Brett Cannoncd171c82013-07-04 17:43:24 -040013except ImportError:
Raymond Hettingerec4b1742013-03-10 17:57:28 -070014 from collections import deque as _deque
Guido van Rossum7f5013a1998-04-09 22:01:42 +000015
Benjamin Petersonb3085c92008-09-01 23:09:31 +000016# Note regarding PEP 8 compliant names
17# This threading model was originally inspired by Java, and inherited
18# the convention of camelCase function and method names from that
Ezio Melotti30b9d5d2013-08-17 15:50:46 +030019# language. Those original names are not in any imminent danger of
Benjamin Petersonb3085c92008-09-01 23:09:31 +000020# being deprecated (even for Py3k),so this module provides them as an
21# alias for the PEP 8 compliant names
22# Note that using the new PEP 8 compliant names facilitates substitution
23# with the multiprocessing module, which doesn't provide the old
24# Java inspired names.
25
Victor Stinnerd12e7572019-05-21 12:44:57 +020026__all__ = ['get_ident', 'active_count', 'Condition', 'current_thread',
27 'enumerate', 'main_thread', 'TIMEOUT_MAX',
Martin Panter19e69c52015-11-14 12:46:42 +000028 'Event', 'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore', 'Thread',
29 'Barrier', 'BrokenBarrierError', 'Timer', 'ThreadError',
Victor Stinnercd590a72019-05-28 00:39:52 +020030 'setprofile', 'settrace', 'local', 'stack_size',
31 'excepthook', 'ExceptHookArgs']
Guido van Rossum7f5013a1998-04-09 22:01:42 +000032
Raymond Hettinger5cee47f2011-01-11 19:59:46 +000033# Rename some stuff so "from threading import *" is safe
Georg Brandl2067bfd2008-05-25 13:05:15 +000034_start_new_thread = _thread.start_new_thread
35_allocate_lock = _thread.allocate_lock
Antoine Pitrou7b476992013-09-07 23:38:37 +020036_set_sentinel = _thread._set_sentinel
Victor Stinner2a129742011-05-30 23:02:52 +020037get_ident = _thread.get_ident
Jake Teslerb121f632019-05-22 08:43:17 -070038try:
39 get_native_id = _thread.get_native_id
40 _HAVE_THREAD_NATIVE_ID = True
41 __all__.append('get_native_id')
42except AttributeError:
43 _HAVE_THREAD_NATIVE_ID = False
Georg Brandl2067bfd2008-05-25 13:05:15 +000044ThreadError = _thread.error
Antoine Pitrou434736a2009-11-10 18:46:01 +000045try:
46 _CRLock = _thread.RLock
47except AttributeError:
48 _CRLock = None
Antoine Pitrou7c3e5772010-04-14 15:44:10 +000049TIMEOUT_MAX = _thread.TIMEOUT_MAX
Georg Brandl2067bfd2008-05-25 13:05:15 +000050del _thread
Guido van Rossum7f5013a1998-04-09 22:01:42 +000051
Guido van Rossum7f5013a1998-04-09 22:01:42 +000052
Jeremy Hyltonbfccb352003-06-29 16:58:41 +000053# Support for profile and trace hooks
54
55_profile_hook = None
56_trace_hook = None
57
58def setprofile(func):
Georg Brandlc30b59f2013-10-13 10:43:59 +020059 """Set a profile function for all threads started from the threading module.
60
61 The func will be passed to sys.setprofile() for each thread, before its
62 run() method is called.
63
64 """
Jeremy Hyltonbfccb352003-06-29 16:58:41 +000065 global _profile_hook
66 _profile_hook = func
Tim Petersd1b108b2003-06-29 17:24:17 +000067
Jeremy Hyltonbfccb352003-06-29 16:58:41 +000068def settrace(func):
Georg Brandlc30b59f2013-10-13 10:43:59 +020069 """Set a trace function for all threads started from the threading module.
70
71 The func will be passed to sys.settrace() for each thread, before its run()
72 method is called.
73
74 """
Jeremy Hyltonbfccb352003-06-29 16:58:41 +000075 global _trace_hook
76 _trace_hook = func
Guido van Rossum7f5013a1998-04-09 22:01:42 +000077
78# Synchronization classes
79
80Lock = _allocate_lock
81
Victor Stinner135b6d82012-03-03 01:32:57 +010082def RLock(*args, **kwargs):
Georg Brandlc30b59f2013-10-13 10:43:59 +020083 """Factory function that returns a new reentrant lock.
84
85 A reentrant lock must be released by the thread that acquired it. Once a
86 thread has acquired a reentrant lock, the same thread may acquire it again
87 without blocking; the thread must release it once for each time it has
88 acquired it.
89
90 """
Victor Stinner135b6d82012-03-03 01:32:57 +010091 if _CRLock is None:
92 return _PyRLock(*args, **kwargs)
Antoine Pitrou434736a2009-11-10 18:46:01 +000093 return _CRLock(*args, **kwargs)
Guido van Rossum7f5013a1998-04-09 22:01:42 +000094
Victor Stinner135b6d82012-03-03 01:32:57 +010095class _RLock:
Georg Brandlc30b59f2013-10-13 10:43:59 +020096 """This class implements reentrant lock objects.
97
98 A reentrant lock must be released by the thread that acquired it. Once a
99 thread has acquired a reentrant lock, the same thread may acquire it
100 again without blocking; the thread must release it once for each time it
101 has acquired it.
102
103 """
Tim Petersb90f89a2001-01-15 03:26:36 +0000104
Victor Stinner135b6d82012-03-03 01:32:57 +0100105 def __init__(self):
Guido van Rossumd0648992007-08-20 19:25:41 +0000106 self._block = _allocate_lock()
107 self._owner = None
108 self._count = 0
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000109
110 def __repr__(self):
Guido van Rossumd0648992007-08-20 19:25:41 +0000111 owner = self._owner
Antoine Pitroub0872682009-11-09 16:08:16 +0000112 try:
113 owner = _active[owner].name
114 except KeyError:
115 pass
Raymond Hettinger62f4dad2014-05-25 18:22:35 -0700116 return "<%s %s.%s object owner=%r count=%d at %s>" % (
117 "locked" if self._block.locked() else "unlocked",
118 self.__class__.__module__,
119 self.__class__.__qualname__,
120 owner,
121 self._count,
122 hex(id(self))
123 )
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000124
Victor Stinner87255be2020-04-07 23:11:49 +0200125 def _at_fork_reinit(self):
126 self._block._at_fork_reinit()
127 self._owner = None
128 self._count = 0
129
Antoine Pitrou7c3e5772010-04-14 15:44:10 +0000130 def acquire(self, blocking=True, timeout=-1):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200131 """Acquire a lock, blocking or non-blocking.
132
133 When invoked without arguments: if this thread already owns the lock,
134 increment the recursion level by one, and return immediately. Otherwise,
135 if another thread owns the lock, block until the lock is unlocked. Once
136 the lock is unlocked (not owned by any thread), then grab ownership, set
137 the recursion level to one, and return. If more than one thread is
138 blocked waiting until the lock is unlocked, only one at a time will be
139 able to grab ownership of the lock. There is no return value in this
140 case.
141
142 When invoked with the blocking argument set to true, do the same thing
143 as when called without arguments, and return true.
144
145 When invoked with the blocking argument set to false, do not block. If a
146 call without an argument would block, return false immediately;
147 otherwise, do the same thing as when called without arguments, and
148 return true.
149
150 When invoked with the floating-point timeout argument set to a positive
151 value, block for at most the number of seconds specified by timeout
152 and as long as the lock cannot be acquired. Return true if the lock has
153 been acquired, false if the timeout has elapsed.
154
155 """
Victor Stinner2a129742011-05-30 23:02:52 +0200156 me = get_ident()
Antoine Pitroub0872682009-11-09 16:08:16 +0000157 if self._owner == me:
Raymond Hettinger720da572013-03-10 15:13:35 -0700158 self._count += 1
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000159 return 1
Antoine Pitrou7c3e5772010-04-14 15:44:10 +0000160 rc = self._block.acquire(blocking, timeout)
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000161 if rc:
Guido van Rossumd0648992007-08-20 19:25:41 +0000162 self._owner = me
163 self._count = 1
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000164 return rc
165
Guido van Rossum1a5e21e2006-02-28 21:57:43 +0000166 __enter__ = acquire
167
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000168 def release(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200169 """Release a lock, decrementing the recursion level.
170
171 If after the decrement it is zero, reset the lock to unlocked (not owned
172 by any thread), and if any other threads are blocked waiting for the
173 lock to become unlocked, allow exactly one of them to proceed. If after
174 the decrement the recursion level is still nonzero, the lock remains
175 locked and owned by the calling thread.
176
177 Only call this method when the calling thread owns the lock. A
178 RuntimeError is raised if this method is called when the lock is
179 unlocked.
180
181 There is no return value.
182
183 """
Victor Stinner2a129742011-05-30 23:02:52 +0200184 if self._owner != get_ident():
Georg Brandl495f7b52009-10-27 15:28:25 +0000185 raise RuntimeError("cannot release un-acquired lock")
Guido van Rossumd0648992007-08-20 19:25:41 +0000186 self._count = count = self._count - 1
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000187 if not count:
Guido van Rossumd0648992007-08-20 19:25:41 +0000188 self._owner = None
189 self._block.release()
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000190
Guido van Rossum1a5e21e2006-02-28 21:57:43 +0000191 def __exit__(self, t, v, tb):
192 self.release()
Guido van Rossum1a5e21e2006-02-28 21:57:43 +0000193
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000194 # Internal methods used by condition variables
195
Guido van Rossum1bc535d2007-05-15 18:46:22 +0000196 def _acquire_restore(self, state):
Guido van Rossumd0648992007-08-20 19:25:41 +0000197 self._block.acquire()
198 self._count, self._owner = state
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000199
200 def _release_save(self):
Victor Stinnerc2824d42011-04-24 23:41:33 +0200201 if self._count == 0:
202 raise RuntimeError("cannot release un-acquired lock")
Guido van Rossumd0648992007-08-20 19:25:41 +0000203 count = self._count
204 self._count = 0
205 owner = self._owner
206 self._owner = None
207 self._block.release()
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000208 return (count, owner)
209
210 def _is_owned(self):
Victor Stinner2a129742011-05-30 23:02:52 +0200211 return self._owner == get_ident()
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000212
Antoine Pitrou434736a2009-11-10 18:46:01 +0000213_PyRLock = _RLock
214
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000215
Victor Stinner135b6d82012-03-03 01:32:57 +0100216class Condition:
Georg Brandlc30b59f2013-10-13 10:43:59 +0200217 """Class that implements a condition variable.
218
219 A condition variable allows one or more threads to wait until they are
220 notified by another thread.
221
222 If the lock argument is given and not None, it must be a Lock or RLock
223 object, and it is used as the underlying lock. Otherwise, a new RLock object
224 is created and used as the underlying lock.
225
226 """
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000227
Victor Stinner135b6d82012-03-03 01:32:57 +0100228 def __init__(self, lock=None):
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000229 if lock is None:
230 lock = RLock()
Guido van Rossumd0648992007-08-20 19:25:41 +0000231 self._lock = lock
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000232 # Export the lock's acquire() and release() methods
233 self.acquire = lock.acquire
234 self.release = lock.release
235 # If the lock defines _release_save() and/or _acquire_restore(),
236 # these override the default implementations (which just call
237 # release() and acquire() on the lock). Ditto for _is_owned().
238 try:
239 self._release_save = lock._release_save
240 except AttributeError:
241 pass
242 try:
243 self._acquire_restore = lock._acquire_restore
244 except AttributeError:
245 pass
246 try:
247 self._is_owned = lock._is_owned
248 except AttributeError:
249 pass
Raymond Hettingerec4b1742013-03-10 17:57:28 -0700250 self._waiters = _deque()
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000251
Victor Stinner87255be2020-04-07 23:11:49 +0200252 def _at_fork_reinit(self):
253 self._lock._at_fork_reinit()
254 self._waiters.clear()
255
Thomas Wouters477c8d52006-05-27 19:21:47 +0000256 def __enter__(self):
Guido van Rossumd0648992007-08-20 19:25:41 +0000257 return self._lock.__enter__()
Guido van Rossum1a5e21e2006-02-28 21:57:43 +0000258
Thomas Wouters477c8d52006-05-27 19:21:47 +0000259 def __exit__(self, *args):
Guido van Rossumd0648992007-08-20 19:25:41 +0000260 return self._lock.__exit__(*args)
Guido van Rossum1a5e21e2006-02-28 21:57:43 +0000261
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000262 def __repr__(self):
Guido van Rossumd0648992007-08-20 19:25:41 +0000263 return "<Condition(%s, %d)>" % (self._lock, len(self._waiters))
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000264
265 def _release_save(self):
Guido van Rossumd0648992007-08-20 19:25:41 +0000266 self._lock.release() # No state to save
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000267
268 def _acquire_restore(self, x):
Guido van Rossumd0648992007-08-20 19:25:41 +0000269 self._lock.acquire() # Ignore saved state
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000270
271 def _is_owned(self):
Benjamin Peterson672b8032008-06-11 19:14:14 +0000272 # Return True if lock is owned by current_thread.
Serhiy Storchaka52005c22014-09-21 22:08:13 +0300273 # This method is called only if _lock doesn't have _is_owned().
Serhiy Storchaka1f21eaa2019-09-01 12:16:51 +0300274 if self._lock.acquire(False):
Guido van Rossumd0648992007-08-20 19:25:41 +0000275 self._lock.release()
Tim Petersbc0e9102002-04-04 22:55:58 +0000276 return False
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000277 else:
Tim Petersbc0e9102002-04-04 22:55:58 +0000278 return True
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000279
280 def wait(self, timeout=None):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200281 """Wait until notified or until a timeout occurs.
282
283 If the calling thread has not acquired the lock when this method is
284 called, a RuntimeError is raised.
285
286 This method releases the underlying lock, and then blocks until it is
287 awakened by a notify() or notify_all() call for the same condition
288 variable in another thread, or until the optional timeout occurs. Once
289 awakened or timed out, it re-acquires the lock and returns.
290
291 When the timeout argument is present and not None, it should be a
292 floating point number specifying a timeout for the operation in seconds
293 (or fractions thereof).
294
295 When the underlying lock is an RLock, it is not released using its
296 release() method, since this may not actually unlock the lock when it
297 was acquired multiple times recursively. Instead, an internal interface
298 of the RLock class is used, which really unlocks it even when it has
299 been recursively acquired several times. Another internal interface is
300 then used to restore the recursion level when the lock is reacquired.
301
302 """
Guido van Rossumcd16bf62007-06-13 18:07:49 +0000303 if not self._is_owned():
Georg Brandl495f7b52009-10-27 15:28:25 +0000304 raise RuntimeError("cannot wait on un-acquired lock")
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000305 waiter = _allocate_lock()
306 waiter.acquire()
Guido van Rossumd0648992007-08-20 19:25:41 +0000307 self._waiters.append(waiter)
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000308 saved_state = self._release_save()
Antoine Pitroua64b92e2014-08-29 23:26:36 +0200309 gotit = False
Tim Petersc951bf92001-04-02 20:15:57 +0000310 try: # restore state no matter what (e.g., KeyboardInterrupt)
311 if timeout is None:
312 waiter.acquire()
Georg Brandlb9a43912010-10-28 09:03:20 +0000313 gotit = True
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000314 else:
Antoine Pitrou7c3e5772010-04-14 15:44:10 +0000315 if timeout > 0:
316 gotit = waiter.acquire(True, timeout)
317 else:
318 gotit = waiter.acquire(False)
Georg Brandlb9a43912010-10-28 09:03:20 +0000319 return gotit
Tim Petersc951bf92001-04-02 20:15:57 +0000320 finally:
321 self._acquire_restore(saved_state)
Antoine Pitroua64b92e2014-08-29 23:26:36 +0200322 if not gotit:
323 try:
324 self._waiters.remove(waiter)
325 except ValueError:
326 pass
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000327
Kristján Valur Jónsson63315202010-11-18 12:46:39 +0000328 def wait_for(self, predicate, timeout=None):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200329 """Wait until a condition evaluates to True.
330
331 predicate should be a callable which result will be interpreted as a
332 boolean value. A timeout may be provided giving the maximum time to
333 wait.
334
335 """
Kristján Valur Jónsson63315202010-11-18 12:46:39 +0000336 endtime = None
337 waittime = timeout
338 result = predicate()
339 while not result:
340 if waittime is not None:
341 if endtime is None:
342 endtime = _time() + waittime
343 else:
344 waittime = endtime - _time()
345 if waittime <= 0:
Kristján Valur Jónsson63315202010-11-18 12:46:39 +0000346 break
Kristján Valur Jónsson63315202010-11-18 12:46:39 +0000347 self.wait(waittime)
348 result = predicate()
Kristján Valur Jónsson63315202010-11-18 12:46:39 +0000349 return result
350
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000351 def notify(self, n=1):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200352 """Wake up one or more threads waiting on this condition, if any.
353
354 If the calling thread has not acquired the lock when this method is
355 called, a RuntimeError is raised.
356
357 This method wakes up at most n of the threads waiting for the condition
358 variable; it is a no-op if no threads are waiting.
359
360 """
Guido van Rossumcd16bf62007-06-13 18:07:49 +0000361 if not self._is_owned():
Georg Brandl495f7b52009-10-27 15:28:25 +0000362 raise RuntimeError("cannot notify on un-acquired lock")
Raymond Hettingerb65e5792013-03-10 20:34:16 -0700363 all_waiters = self._waiters
364 waiters_to_notify = _deque(_islice(all_waiters, n))
365 if not waiters_to_notify:
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000366 return
Raymond Hettingerb65e5792013-03-10 20:34:16 -0700367 for waiter in waiters_to_notify:
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000368 waiter.release()
369 try:
Raymond Hettingerb65e5792013-03-10 20:34:16 -0700370 all_waiters.remove(waiter)
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000371 except ValueError:
372 pass
373
Benjamin Peterson672b8032008-06-11 19:14:14 +0000374 def notify_all(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200375 """Wake up all threads waiting on this condition.
376
377 If the calling thread has not acquired the lock when this method
378 is called, a RuntimeError is raised.
379
380 """
Guido van Rossumd0648992007-08-20 19:25:41 +0000381 self.notify(len(self._waiters))
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000382
Benjamin Petersonb3085c92008-09-01 23:09:31 +0000383 notifyAll = notify_all
384
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000385
Victor Stinner135b6d82012-03-03 01:32:57 +0100386class Semaphore:
Georg Brandlc30b59f2013-10-13 10:43:59 +0200387 """This class implements semaphore objects.
388
389 Semaphores manage a counter representing the number of release() calls minus
390 the number of acquire() calls, plus an initial value. The acquire() method
391 blocks if necessary until it can return without making the counter
392 negative. If not given, value defaults to 1.
393
394 """
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000395
Andrew M. Kuchling39d3bfc2000-02-29 00:10:24 +0000396 # After Tim Peters' semaphore class, but not quite the same (no maximum)
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000397
Victor Stinner135b6d82012-03-03 01:32:57 +0100398 def __init__(self, value=1):
Guido van Rossumcd16bf62007-06-13 18:07:49 +0000399 if value < 0:
400 raise ValueError("semaphore initial value must be >= 0")
Guido van Rossumd0648992007-08-20 19:25:41 +0000401 self._cond = Condition(Lock())
402 self._value = value
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000403
Antoine Pitrou0454af92010-04-17 23:51:58 +0000404 def acquire(self, blocking=True, timeout=None):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200405 """Acquire a semaphore, decrementing the internal counter by one.
406
407 When invoked without arguments: if the internal counter is larger than
408 zero on entry, decrement it by one and return immediately. If it is zero
409 on entry, block, waiting until some other thread has called release() to
410 make it larger than zero. This is done with proper interlocking so that
411 if multiple acquire() calls are blocked, release() will wake exactly one
412 of them up. The implementation may pick one at random, so the order in
413 which blocked threads are awakened should not be relied on. There is no
414 return value in this case.
415
416 When invoked with blocking set to true, do the same thing as when called
417 without arguments, and return true.
418
419 When invoked with blocking set to false, do not block. If a call without
420 an argument would block, return false immediately; otherwise, do the
421 same thing as when called without arguments, and return true.
422
423 When invoked with a timeout other than None, it will block for at
424 most timeout seconds. If acquire does not complete successfully in
425 that interval, return false. Return true otherwise.
426
427 """
Antoine Pitrou0454af92010-04-17 23:51:58 +0000428 if not blocking and timeout is not None:
429 raise ValueError("can't specify timeout for non-blocking acquire")
Guido van Rossum8ca162f2002-04-07 06:36:23 +0000430 rc = False
Antoine Pitrou0454af92010-04-17 23:51:58 +0000431 endtime = None
Serhiy Storchaka81a58552013-04-22 22:51:43 +0300432 with self._cond:
433 while self._value == 0:
434 if not blocking:
435 break
436 if timeout is not None:
437 if endtime is None:
438 endtime = _time() + timeout
439 else:
440 timeout = endtime - _time()
441 if timeout <= 0:
442 break
443 self._cond.wait(timeout)
444 else:
Serhiy Storchakab00b5962013-04-22 22:54:16 +0300445 self._value -= 1
Serhiy Storchaka81a58552013-04-22 22:51:43 +0300446 rc = True
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000447 return rc
448
Guido van Rossum1a5e21e2006-02-28 21:57:43 +0000449 __enter__ = acquire
450
Raymond Hettinger35f63012019-08-29 01:45:19 -0700451 def release(self, n=1):
452 """Release a semaphore, incrementing the internal counter by one or more.
Georg Brandlc30b59f2013-10-13 10:43:59 +0200453
454 When the counter is zero on entry and another thread is waiting for it
455 to become larger than zero again, wake up that thread.
456
457 """
Raymond Hettinger35f63012019-08-29 01:45:19 -0700458 if n < 1:
459 raise ValueError('n must be one or more')
Serhiy Storchaka81a58552013-04-22 22:51:43 +0300460 with self._cond:
Raymond Hettinger35f63012019-08-29 01:45:19 -0700461 self._value += n
462 for i in range(n):
463 self._cond.notify()
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000464
Guido van Rossum1a5e21e2006-02-28 21:57:43 +0000465 def __exit__(self, t, v, tb):
466 self.release()
Guido van Rossum1a5e21e2006-02-28 21:57:43 +0000467
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000468
Éric Araujo0cdd4452011-07-28 00:28:28 +0200469class BoundedSemaphore(Semaphore):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200470 """Implements a bounded semaphore.
471
472 A bounded semaphore checks to make sure its current value doesn't exceed its
473 initial value. If it does, ValueError is raised. In most situations
474 semaphores are used to guard resources with limited capacity.
475
476 If the semaphore is released too many times it's a sign of a bug. If not
477 given, value defaults to 1.
478
479 Like regular semaphores, bounded semaphores manage a counter representing
480 the number of release() calls minus the number of acquire() calls, plus an
481 initial value. The acquire() method blocks if necessary until it can return
482 without making the counter negative. If not given, value defaults to 1.
483
484 """
485
Victor Stinner135b6d82012-03-03 01:32:57 +0100486 def __init__(self, value=1):
487 Semaphore.__init__(self, value)
Skip Montanaroe428bb72001-08-20 20:27:58 +0000488 self._initial_value = value
489
Raymond Hettinger35f63012019-08-29 01:45:19 -0700490 def release(self, n=1):
491 """Release a semaphore, incrementing the internal counter by one or more.
Georg Brandlc30b59f2013-10-13 10:43:59 +0200492
493 When the counter is zero on entry and another thread is waiting for it
494 to become larger than zero again, wake up that thread.
495
496 If the number of releases exceeds the number of acquires,
497 raise a ValueError.
498
499 """
Raymond Hettinger35f63012019-08-29 01:45:19 -0700500 if n < 1:
501 raise ValueError('n must be one or more')
Tim Peters7634e1c2013-10-08 20:55:51 -0500502 with self._cond:
Raymond Hettinger35f63012019-08-29 01:45:19 -0700503 if self._value + n > self._initial_value:
Tim Peters7634e1c2013-10-08 20:55:51 -0500504 raise ValueError("Semaphore released too many times")
Raymond Hettinger35f63012019-08-29 01:45:19 -0700505 self._value += n
506 for i in range(n):
507 self._cond.notify()
Skip Montanaroe428bb72001-08-20 20:27:58 +0000508
509
Victor Stinner135b6d82012-03-03 01:32:57 +0100510class Event:
Georg Brandlc30b59f2013-10-13 10:43:59 +0200511 """Class implementing event objects.
512
513 Events manage a flag that can be set to true with the set() method and reset
514 to false with the clear() method. The wait() method blocks until the flag is
515 true. The flag is initially false.
516
517 """
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000518
519 # After Tim Peters' event class (without is_posted())
520
Victor Stinner135b6d82012-03-03 01:32:57 +0100521 def __init__(self):
Guido van Rossumd0648992007-08-20 19:25:41 +0000522 self._cond = Condition(Lock())
523 self._flag = False
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000524
Victor Stinner87255be2020-04-07 23:11:49 +0200525 def _at_fork_reinit(self):
526 # Private method called by Thread._reset_internal_locks()
527 self._cond._at_fork_reinit()
Gregory P. Smith9bd4a242011-01-04 18:33:38 +0000528
Benjamin Peterson672b8032008-06-11 19:14:14 +0000529 def is_set(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200530 """Return true if and only if the internal flag is true."""
Guido van Rossumd0648992007-08-20 19:25:41 +0000531 return self._flag
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000532
Benjamin Petersonb3085c92008-09-01 23:09:31 +0000533 isSet = is_set
Benjamin Petersonf0923f52008-08-18 22:10:13 +0000534
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000535 def set(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200536 """Set the internal flag to true.
537
538 All threads waiting for it to become true are awakened. Threads
539 that call wait() once the flag is true will not block at all.
540
541 """
Benjamin Peterson414918a2015-10-10 19:34:46 -0700542 with self._cond:
Guido van Rossumd0648992007-08-20 19:25:41 +0000543 self._flag = True
Benjamin Peterson672b8032008-06-11 19:14:14 +0000544 self._cond.notify_all()
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000545
546 def clear(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200547 """Reset the internal flag to false.
548
549 Subsequently, threads calling wait() will block until set() is called to
550 set the internal flag to true again.
551
552 """
Benjamin Peterson414918a2015-10-10 19:34:46 -0700553 with self._cond:
Guido van Rossumd0648992007-08-20 19:25:41 +0000554 self._flag = False
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000555
556 def wait(self, timeout=None):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200557 """Block until the internal flag is true.
558
559 If the internal flag is true on entry, return immediately. Otherwise,
560 block until another thread calls set() to set the flag to true, or until
561 the optional timeout occurs.
562
563 When the timeout argument is present and not None, it should be a
564 floating point number specifying a timeout for the operation in seconds
565 (or fractions thereof).
566
567 This method returns the internal flag on exit, so it will always return
568 True except if a timeout is given and the operation times out.
569
570 """
Benjamin Peterson414918a2015-10-10 19:34:46 -0700571 with self._cond:
Charles-François Natalided03482012-01-07 18:24:56 +0100572 signaled = self._flag
573 if not signaled:
574 signaled = self._cond.wait(timeout)
575 return signaled
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000576
Kristján Valur Jónsson3be00032010-10-28 09:43:10 +0000577
578# A barrier class. Inspired in part by the pthread_barrier_* api and
579# the CyclicBarrier class from Java. See
580# http://sourceware.org/pthreads-win32/manual/pthread_barrier_init.html and
581# http://java.sun.com/j2se/1.5.0/docs/api/java/util/concurrent/
582# CyclicBarrier.html
583# for information.
584# We maintain two main states, 'filling' and 'draining' enabling the barrier
585# to be cyclic. Threads are not allowed into it until it has fully drained
586# since the previous cycle. In addition, a 'resetting' state exists which is
587# similar to 'draining' except that threads leave with a BrokenBarrierError,
Ezio Melottie130a522011-10-19 10:58:56 +0300588# and a 'broken' state in which all threads get the exception.
Victor Stinner135b6d82012-03-03 01:32:57 +0100589class Barrier:
Georg Brandlc30b59f2013-10-13 10:43:59 +0200590 """Implements a Barrier.
591
592 Useful for synchronizing a fixed number of threads at known synchronization
Carl Bordum Hansen62fa51f2019-03-09 18:38:05 +0100593 points. Threads block on 'wait()' and are simultaneously awoken once they
594 have all made that call.
Georg Brandlc30b59f2013-10-13 10:43:59 +0200595
Kristján Valur Jónsson3be00032010-10-28 09:43:10 +0000596 """
Georg Brandlc30b59f2013-10-13 10:43:59 +0200597
Victor Stinner135b6d82012-03-03 01:32:57 +0100598 def __init__(self, parties, action=None, timeout=None):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200599 """Create a barrier, initialised to 'parties' threads.
600
601 'action' is a callable which, when supplied, will be called by one of
602 the threads after they have all entered the barrier and just prior to
Carl Bordum Hansen62fa51f2019-03-09 18:38:05 +0100603 releasing them all. If a 'timeout' is provided, it is used as the
Georg Brandlc30b59f2013-10-13 10:43:59 +0200604 default for all subsequent 'wait()' calls.
605
Kristján Valur Jónsson3be00032010-10-28 09:43:10 +0000606 """
Kristján Valur Jónsson3be00032010-10-28 09:43:10 +0000607 self._cond = Condition(Lock())
608 self._action = action
609 self._timeout = timeout
610 self._parties = parties
611 self._state = 0 #0 filling, 1, draining, -1 resetting, -2 broken
612 self._count = 0
613
614 def wait(self, timeout=None):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200615 """Wait for the barrier.
616
617 When the specified number of threads have started waiting, they are all
618 simultaneously awoken. If an 'action' was provided for the barrier, one
619 of the threads will have executed that callback prior to returning.
Kristján Valur Jónsson3be00032010-10-28 09:43:10 +0000620 Returns an individual index number from 0 to 'parties-1'.
Georg Brandlc30b59f2013-10-13 10:43:59 +0200621
Kristján Valur Jónsson3be00032010-10-28 09:43:10 +0000622 """
623 if timeout is None:
624 timeout = self._timeout
625 with self._cond:
626 self._enter() # Block while the barrier drains.
627 index = self._count
628 self._count += 1
629 try:
630 if index + 1 == self._parties:
631 # We release the barrier
632 self._release()
633 else:
634 # We wait until someone releases us
635 self._wait(timeout)
636 return index
637 finally:
638 self._count -= 1
639 # Wake up any threads waiting for barrier to drain.
640 self._exit()
641
642 # Block until the barrier is ready for us, or raise an exception
643 # if it is broken.
644 def _enter(self):
645 while self._state in (-1, 1):
646 # It is draining or resetting, wait until done
647 self._cond.wait()
648 #see if the barrier is in a broken state
649 if self._state < 0:
650 raise BrokenBarrierError
651 assert self._state == 0
652
653 # Optionally run the 'action' and release the threads waiting
654 # in the barrier.
655 def _release(self):
656 try:
657 if self._action:
658 self._action()
659 # enter draining state
660 self._state = 1
661 self._cond.notify_all()
662 except:
663 #an exception during the _action handler. Break and reraise
664 self._break()
665 raise
666
Martin Panter69332c12016-08-04 13:07:31 +0000667 # Wait in the barrier until we are released. Raise an exception
Kristján Valur Jónsson3be00032010-10-28 09:43:10 +0000668 # if the barrier is reset or broken.
669 def _wait(self, timeout):
Kristján Valur Jónsson63315202010-11-18 12:46:39 +0000670 if not self._cond.wait_for(lambda : self._state != 0, timeout):
671 #timed out. Break the barrier
672 self._break()
673 raise BrokenBarrierError
674 if self._state < 0:
675 raise BrokenBarrierError
Kristján Valur Jónsson3be00032010-10-28 09:43:10 +0000676 assert self._state == 1
677
678 # If we are the last thread to exit the barrier, signal any threads
679 # waiting for the barrier to drain.
680 def _exit(self):
681 if self._count == 0:
682 if self._state in (-1, 1):
683 #resetting or draining
684 self._state = 0
685 self._cond.notify_all()
686
687 def reset(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200688 """Reset the barrier to the initial state.
689
Kristján Valur Jónsson3be00032010-10-28 09:43:10 +0000690 Any threads currently waiting will get the BrokenBarrier exception
691 raised.
Georg Brandlc30b59f2013-10-13 10:43:59 +0200692
Kristján Valur Jónsson3be00032010-10-28 09:43:10 +0000693 """
694 with self._cond:
695 if self._count > 0:
696 if self._state == 0:
697 #reset the barrier, waking up threads
698 self._state = -1
699 elif self._state == -2:
700 #was broken, set it to reset state
701 #which clears when the last thread exits
702 self._state = -1
703 else:
704 self._state = 0
705 self._cond.notify_all()
706
707 def abort(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200708 """Place the barrier into a 'broken' state.
709
710 Useful in case of error. Any currently waiting threads and threads
711 attempting to 'wait()' will have BrokenBarrierError raised.
712
Kristján Valur Jónsson3be00032010-10-28 09:43:10 +0000713 """
714 with self._cond:
715 self._break()
716
717 def _break(self):
718 # An internal error was detected. The barrier is set to
719 # a broken state all parties awakened.
720 self._state = -2
721 self._cond.notify_all()
722
723 @property
724 def parties(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200725 """Return the number of threads required to trip the barrier."""
Kristján Valur Jónsson3be00032010-10-28 09:43:10 +0000726 return self._parties
727
728 @property
729 def n_waiting(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200730 """Return the number of threads currently waiting at the barrier."""
Kristján Valur Jónsson3be00032010-10-28 09:43:10 +0000731 # We don't need synchronization here since this is an ephemeral result
732 # anyway. It returns the correct value in the steady state.
733 if self._state == 0:
734 return self._count
735 return 0
736
737 @property
738 def broken(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200739 """Return True if the barrier is in a broken state."""
Kristján Valur Jónsson3be00032010-10-28 09:43:10 +0000740 return self._state == -2
741
Georg Brandlc30b59f2013-10-13 10:43:59 +0200742# exception raised by the Barrier class
743class BrokenBarrierError(RuntimeError):
744 pass
Kristján Valur Jónsson3be00032010-10-28 09:43:10 +0000745
746
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000747# Helper to generate new thread names
R David Murrayb186f1df2014-10-04 17:43:54 -0400748_counter = _count().__next__
749_counter() # Consume 0 so first non-main thread has id 1.
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000750def _newname(template="Thread-%d"):
R David Murrayb186f1df2014-10-04 17:43:54 -0400751 return template % _counter()
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000752
753# Active thread administration
754_active_limbo_lock = _allocate_lock()
Tim Peters711906e2005-01-08 07:30:42 +0000755_active = {} # maps thread id to Thread object
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000756_limbo = {}
Antoine Pitrouc081c0c2011-07-15 22:12:24 +0200757_dangling = WeakSet()
Victor Stinner468e5fe2019-06-13 01:30:17 +0200758# Set of Thread._tstate_lock locks of non-daemon threads used by _shutdown()
759# to wait until all Python thread states get deleted:
760# see Thread._set_tstate_lock().
761_shutdown_locks_lock = _allocate_lock()
762_shutdown_locks = set()
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000763
764# Main class for threads
765
Victor Stinner135b6d82012-03-03 01:32:57 +0100766class Thread:
Georg Brandlc30b59f2013-10-13 10:43:59 +0200767 """A class that represents a thread of control.
768
769 This class can be safely subclassed in a limited fashion. There are two ways
770 to specify the activity: by passing a callable object to the constructor, or
771 by overriding the run() method in a subclass.
772
773 """
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000774
Serhiy Storchaka52005c22014-09-21 22:08:13 +0300775 _initialized = False
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000776
777 def __init__(self, group=None, target=None, name=None,
Victor Stinner135b6d82012-03-03 01:32:57 +0100778 args=(), kwargs=None, *, daemon=None):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200779 """This constructor should always be called with keyword arguments. Arguments are:
780
781 *group* should be None; reserved for future extension when a ThreadGroup
782 class is implemented.
783
784 *target* is the callable object to be invoked by the run()
785 method. Defaults to None, meaning nothing is called.
786
787 *name* is the thread name. By default, a unique name is constructed of
788 the form "Thread-N" where N is a small decimal number.
789
790 *args* is the argument tuple for the target invocation. Defaults to ().
791
792 *kwargs* is a dictionary of keyword arguments for the target
793 invocation. Defaults to {}.
794
795 If a subclass overrides the constructor, it must make sure to invoke
796 the base class constructor (Thread.__init__()) before doing anything
797 else to the thread.
798
799 """
Guido van Rossum5a43e1a1998-06-09 19:04:26 +0000800 assert group is None, "group argument must be None for now"
Georg Brandla4a8b822005-07-15 09:13:21 +0000801 if kwargs is None:
802 kwargs = {}
Guido van Rossumd0648992007-08-20 19:25:41 +0000803 self._target = target
804 self._name = str(name or _newname())
805 self._args = args
806 self._kwargs = kwargs
Antoine Pitrou0bd4deb2011-02-25 22:07:43 +0000807 if daemon is not None:
808 self._daemonic = daemon
809 else:
810 self._daemonic = current_thread().daemon
Georg Brandl0c77a822008-06-10 16:37:50 +0000811 self._ident = None
Jake Teslerb121f632019-05-22 08:43:17 -0700812 if _HAVE_THREAD_NATIVE_ID:
813 self._native_id = None
Antoine Pitrou7b476992013-09-07 23:38:37 +0200814 self._tstate_lock = None
Christian Heimes9e7f1d22008-02-28 12:27:11 +0000815 self._started = Event()
Tim Petersc363a232013-09-08 18:44:40 -0500816 self._is_stopped = False
Guido van Rossumd0648992007-08-20 19:25:41 +0000817 self._initialized = True
Victor Stinnercd590a72019-05-28 00:39:52 +0200818 # Copy of sys.stderr used by self._invoke_excepthook()
Guido van Rossumd0648992007-08-20 19:25:41 +0000819 self._stderr = _sys.stderr
Victor Stinnercd590a72019-05-28 00:39:52 +0200820 self._invoke_excepthook = _make_invoke_excepthook()
Antoine Pitrou5da7e792013-09-08 13:19:06 +0200821 # For debugging and _after_fork()
Antoine Pitrouc081c0c2011-07-15 22:12:24 +0200822 _dangling.add(self)
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000823
Antoine Pitrou7b476992013-09-07 23:38:37 +0200824 def _reset_internal_locks(self, is_alive):
Gregory P. Smith9bd4a242011-01-04 18:33:38 +0000825 # private! Called by _after_fork() to reset our internal locks as
826 # they may be in an invalid state leading to a deadlock or crash.
Victor Stinner87255be2020-04-07 23:11:49 +0200827 self._started._at_fork_reinit()
Antoine Pitrou7b476992013-09-07 23:38:37 +0200828 if is_alive:
Miss Islington (bot)cf708542020-11-16 07:17:17 -0800829 # bpo-42350: If the fork happens when the thread is already stopped
830 # (ex: after threading._shutdown() has been called), _tstate_lock
831 # is None. Do nothing in this case.
832 if self._tstate_lock is not None:
833 self._tstate_lock._at_fork_reinit()
834 self._tstate_lock.acquire()
Antoine Pitrou7b476992013-09-07 23:38:37 +0200835 else:
836 # The thread isn't alive after fork: it doesn't have a tstate
837 # anymore.
Tim Petersb5e9ac92013-09-09 14:41:50 -0500838 self._is_stopped = True
Antoine Pitrou7b476992013-09-07 23:38:37 +0200839 self._tstate_lock = None
Gregory P. Smith9bd4a242011-01-04 18:33:38 +0000840
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000841 def __repr__(self):
Guido van Rossumd0648992007-08-20 19:25:41 +0000842 assert self._initialized, "Thread.__init__() was not called"
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000843 status = "initial"
Benjamin Peterson672b8032008-06-11 19:14:14 +0000844 if self._started.is_set():
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000845 status = "started"
Tim Peters72460fa2013-09-09 18:48:24 -0500846 self.is_alive() # easy way to get ._is_stopped set when appropriate
Tim Petersc363a232013-09-08 18:44:40 -0500847 if self._is_stopped:
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000848 status = "stopped"
Guido van Rossumd0648992007-08-20 19:25:41 +0000849 if self._daemonic:
Georg Brandl0c77a822008-06-10 16:37:50 +0000850 status += " daemon"
851 if self._ident is not None:
852 status += " %s" % self._ident
Guido van Rossumd0648992007-08-20 19:25:41 +0000853 return "<%s(%s, %s)>" % (self.__class__.__name__, self._name, status)
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000854
855 def start(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200856 """Start the thread's activity.
857
858 It must be called at most once per thread object. It arranges for the
859 object's run() method to be invoked in a separate thread of control.
860
861 This method will raise a RuntimeError if called more than once on the
862 same thread object.
863
864 """
Guido van Rossumd0648992007-08-20 19:25:41 +0000865 if not self._initialized:
Guido van Rossumcd16bf62007-06-13 18:07:49 +0000866 raise RuntimeError("thread.__init__() not called")
Christian Heimes9e7f1d22008-02-28 12:27:11 +0000867
Benjamin Peterson672b8032008-06-11 19:14:14 +0000868 if self._started.is_set():
Senthil Kumaranfdd4d0f2010-04-06 03:30:18 +0000869 raise RuntimeError("threads can only be started once")
Victor Stinner066e5b12019-06-14 18:55:22 +0200870
Benjamin Petersond23f8222009-04-05 19:13:16 +0000871 with _active_limbo_lock:
872 _limbo[self] = self
Gregory P. Smith3fdd9642010-02-28 18:57:46 +0000873 try:
874 _start_new_thread(self._bootstrap, ())
875 except Exception:
876 with _active_limbo_lock:
877 del _limbo[self]
878 raise
Christian Heimes9e7f1d22008-02-28 12:27:11 +0000879 self._started.wait()
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000880
881 def run(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +0200882 """Method representing the thread's activity.
883
884 You may override this method in a subclass. The standard run() method
885 invokes the callable object passed to the object's constructor as the
886 target argument, if any, with sequential and keyword arguments taken
887 from the args and kwargs arguments, respectively.
888
889 """
Christian Heimesd3eb5a152008-02-24 00:38:49 +0000890 try:
891 if self._target:
892 self._target(*self._args, **self._kwargs)
893 finally:
894 # Avoid a refcycle if the thread is running a function with
895 # an argument that has a member that points to the thread.
896 del self._target, self._args, self._kwargs
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000897
Guido van Rossumd0648992007-08-20 19:25:41 +0000898 def _bootstrap(self):
Guido van Rossum61e21b52007-08-20 19:06:03 +0000899 # Wrapper around the real bootstrap code that ignores
900 # exceptions during interpreter cleanup. Those typically
901 # happen when a daemon thread wakes up at an unfortunate
902 # moment, finds the world around it destroyed, and raises some
903 # random exception *** while trying to report the exception in
Christian Heimes9e7f1d22008-02-28 12:27:11 +0000904 # _bootstrap_inner() below ***. Those random exceptions
Guido van Rossum61e21b52007-08-20 19:06:03 +0000905 # don't help anybody, and they confuse users, so we suppress
906 # them. We suppress them only when it appears that the world
907 # indeed has already been destroyed, so that exceptions in
Christian Heimes9e7f1d22008-02-28 12:27:11 +0000908 # _bootstrap_inner() during normal business hours are properly
Guido van Rossum61e21b52007-08-20 19:06:03 +0000909 # reported. Also, we only suppress them for daemonic threads;
910 # if a non-daemonic encounters this, something else is wrong.
911 try:
Guido van Rossumd0648992007-08-20 19:25:41 +0000912 self._bootstrap_inner()
Guido van Rossum61e21b52007-08-20 19:06:03 +0000913 except:
Guido van Rossumd0648992007-08-20 19:25:41 +0000914 if self._daemonic and _sys is None:
Guido van Rossum61e21b52007-08-20 19:06:03 +0000915 return
916 raise
917
Benjamin Petersond23f8222009-04-05 19:13:16 +0000918 def _set_ident(self):
Victor Stinner2a129742011-05-30 23:02:52 +0200919 self._ident = get_ident()
Benjamin Petersond23f8222009-04-05 19:13:16 +0000920
Jake Teslerb121f632019-05-22 08:43:17 -0700921 if _HAVE_THREAD_NATIVE_ID:
922 def _set_native_id(self):
923 self._native_id = get_native_id()
924
Antoine Pitrou7b476992013-09-07 23:38:37 +0200925 def _set_tstate_lock(self):
926 """
927 Set a lock object which will be released by the interpreter when
928 the underlying thread state (see pystate.h) gets deleted.
929 """
930 self._tstate_lock = _set_sentinel()
931 self._tstate_lock.acquire()
932
Victor Stinner468e5fe2019-06-13 01:30:17 +0200933 if not self.daemon:
934 with _shutdown_locks_lock:
935 _shutdown_locks.add(self._tstate_lock)
936
Guido van Rossumd0648992007-08-20 19:25:41 +0000937 def _bootstrap_inner(self):
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000938 try:
Benjamin Petersond23f8222009-04-05 19:13:16 +0000939 self._set_ident()
Antoine Pitrou7b476992013-09-07 23:38:37 +0200940 self._set_tstate_lock()
Jake Teslerb121f632019-05-22 08:43:17 -0700941 if _HAVE_THREAD_NATIVE_ID:
942 self._set_native_id()
Christian Heimes9e7f1d22008-02-28 12:27:11 +0000943 self._started.set()
Benjamin Petersond23f8222009-04-05 19:13:16 +0000944 with _active_limbo_lock:
945 _active[self._ident] = self
946 del _limbo[self]
Jeremy Hyltonbfccb352003-06-29 16:58:41 +0000947
948 if _trace_hook:
Jeremy Hyltonbfccb352003-06-29 16:58:41 +0000949 _sys.settrace(_trace_hook)
950 if _profile_hook:
Jeremy Hyltonbfccb352003-06-29 16:58:41 +0000951 _sys.setprofile(_profile_hook)
Tim Petersd1b108b2003-06-29 17:24:17 +0000952
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000953 try:
954 self.run()
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000955 except:
Victor Stinnercd590a72019-05-28 00:39:52 +0200956 self._invoke_excepthook(self)
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000957 finally:
Christian Heimes1af737c2008-01-23 08:24:23 +0000958 with _active_limbo_lock:
Christian Heimes1af737c2008-01-23 08:24:23 +0000959 try:
Georg Brandl0c77a822008-06-10 16:37:50 +0000960 # We don't call self._delete() because it also
Christian Heimes1af737c2008-01-23 08:24:23 +0000961 # grabs _active_limbo_lock.
Victor Stinner2a129742011-05-30 23:02:52 +0200962 del _active[get_ident()]
Christian Heimes1af737c2008-01-23 08:24:23 +0000963 except:
964 pass
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000965
Guido van Rossumd0648992007-08-20 19:25:41 +0000966 def _stop(self):
Tim Petersb5e9ac92013-09-09 14:41:50 -0500967 # After calling ._stop(), .is_alive() returns False and .join() returns
968 # immediately. ._tstate_lock must be released before calling ._stop().
969 #
970 # Normal case: C code at the end of the thread's life
971 # (release_sentinel in _threadmodule.c) releases ._tstate_lock, and
972 # that's detected by our ._wait_for_tstate_lock(), called by .join()
973 # and .is_alive(). Any number of threads _may_ call ._stop()
974 # simultaneously (for example, if multiple threads are blocked in
975 # .join() calls), and they're not serialized. That's harmless -
976 # they'll just make redundant rebindings of ._is_stopped and
977 # ._tstate_lock. Obscure: we rebind ._tstate_lock last so that the
978 # "assert self._is_stopped" in ._wait_for_tstate_lock() always works
979 # (the assert is executed only if ._tstate_lock is None).
980 #
981 # Special case: _main_thread releases ._tstate_lock via this
982 # module's _shutdown() function.
983 lock = self._tstate_lock
984 if lock is not None:
985 assert not lock.locked()
Tim Peters78755232013-09-09 13:47:16 -0500986 self._is_stopped = True
987 self._tstate_lock = None
Victor Stinner468e5fe2019-06-13 01:30:17 +0200988 if not self.daemon:
989 with _shutdown_locks_lock:
Victor Stinner6f75c872019-06-13 12:06:24 +0200990 _shutdown_locks.discard(lock)
Guido van Rossum7f5013a1998-04-09 22:01:42 +0000991
Guido van Rossumd0648992007-08-20 19:25:41 +0000992 def _delete(self):
Tim Peters21429932004-07-21 03:36:52 +0000993 "Remove current thread from the dict of currently running threads."
Antoine Pitroua6a4dc82017-09-07 18:56:24 +0200994 with _active_limbo_lock:
995 del _active[get_ident()]
996 # There must not be any python code between the previous line
997 # and after the lock is released. Otherwise a tracing function
998 # could try to acquire the lock again in the same thread, (in
999 # current_thread()), and would block.
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001000
1001 def join(self, timeout=None):
Georg Brandlc30b59f2013-10-13 10:43:59 +02001002 """Wait until the thread terminates.
1003
1004 This blocks the calling thread until the thread whose join() method is
1005 called terminates -- either normally or through an unhandled exception
1006 or until the optional timeout occurs.
1007
1008 When the timeout argument is present and not None, it should be a
1009 floating point number specifying a timeout for the operation in seconds
1010 (or fractions thereof). As join() always returns None, you must call
Dong-hee Na36d9e9a2019-01-18 18:50:47 +09001011 is_alive() after join() to decide whether a timeout happened -- if the
Georg Brandlc30b59f2013-10-13 10:43:59 +02001012 thread is still alive, the join() call timed out.
1013
1014 When the timeout argument is not present or None, the operation will
1015 block until the thread terminates.
1016
1017 A thread can be join()ed many times.
1018
1019 join() raises a RuntimeError if an attempt is made to join the current
1020 thread as that would cause a deadlock. It is also an error to join() a
1021 thread before it has been started and attempts to do so raises the same
1022 exception.
1023
1024 """
Guido van Rossumd0648992007-08-20 19:25:41 +00001025 if not self._initialized:
Guido van Rossumcd16bf62007-06-13 18:07:49 +00001026 raise RuntimeError("Thread.__init__() not called")
Benjamin Peterson672b8032008-06-11 19:14:14 +00001027 if not self._started.is_set():
Guido van Rossumcd16bf62007-06-13 18:07:49 +00001028 raise RuntimeError("cannot join thread before it is started")
Benjamin Peterson672b8032008-06-11 19:14:14 +00001029 if self is current_thread():
Guido van Rossumcd16bf62007-06-13 18:07:49 +00001030 raise RuntimeError("cannot join current thread")
Tim Peterse5bb0bf2013-10-25 20:46:51 -05001031
Tim Petersc363a232013-09-08 18:44:40 -05001032 if timeout is None:
1033 self._wait_for_tstate_lock()
Tim Peters7bad39f2013-10-25 22:33:52 -05001034 else:
1035 # the behavior of a negative timeout isn't documented, but
Tim Petersa577f1e2013-10-26 11:56:16 -05001036 # historically .join(timeout=x) for x<0 has acted as if timeout=0
Tim Peters7bad39f2013-10-25 22:33:52 -05001037 self._wait_for_tstate_lock(timeout=max(timeout, 0))
Guido van Rossumcd16bf62007-06-13 18:07:49 +00001038
Tim Petersc363a232013-09-08 18:44:40 -05001039 def _wait_for_tstate_lock(self, block=True, timeout=-1):
Antoine Pitrou7b476992013-09-07 23:38:37 +02001040 # Issue #18808: wait for the thread state to be gone.
Tim Petersc363a232013-09-08 18:44:40 -05001041 # At the end of the thread's life, after all knowledge of the thread
1042 # is removed from C data structures, C code releases our _tstate_lock.
Martin Panter46f50722016-05-26 05:35:26 +00001043 # This method passes its arguments to _tstate_lock.acquire().
Tim Petersc363a232013-09-08 18:44:40 -05001044 # If the lock is acquired, the C code is done, and self._stop() is
1045 # called. That sets ._is_stopped to True, and ._tstate_lock to None.
Antoine Pitrou7b476992013-09-07 23:38:37 +02001046 lock = self._tstate_lock
Tim Petersc363a232013-09-08 18:44:40 -05001047 if lock is None: # already determined that the C code is done
1048 assert self._is_stopped
1049 elif lock.acquire(block, timeout):
Antoine Pitrou7b476992013-09-07 23:38:37 +02001050 lock.release()
Tim Petersc363a232013-09-08 18:44:40 -05001051 self._stop()
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001052
Benjamin Petersonfdbea962008-08-18 17:33:47 +00001053 @property
1054 def name(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +02001055 """A string used for identification purposes only.
1056
1057 It has no semantics. Multiple threads may be given the same name. The
1058 initial name is set by the constructor.
1059
1060 """
Guido van Rossumd0648992007-08-20 19:25:41 +00001061 assert self._initialized, "Thread.__init__() not called"
1062 return self._name
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001063
Benjamin Petersonfdbea962008-08-18 17:33:47 +00001064 @name.setter
1065 def name(self, name):
Guido van Rossumd0648992007-08-20 19:25:41 +00001066 assert self._initialized, "Thread.__init__() not called"
1067 self._name = str(name)
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001068
Benjamin Peterson773c17b2008-08-18 16:45:31 +00001069 @property
1070 def ident(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +02001071 """Thread identifier of this thread or None if it has not been started.
1072
Skip Montanaro56343312018-05-18 13:38:36 -05001073 This is a nonzero integer. See the get_ident() function. Thread
Georg Brandlc30b59f2013-10-13 10:43:59 +02001074 identifiers may be recycled when a thread exits and another thread is
1075 created. The identifier is available even after the thread has exited.
1076
1077 """
Georg Brandl0c77a822008-06-10 16:37:50 +00001078 assert self._initialized, "Thread.__init__() not called"
1079 return self._ident
1080
Jake Teslerb121f632019-05-22 08:43:17 -07001081 if _HAVE_THREAD_NATIVE_ID:
1082 @property
1083 def native_id(self):
1084 """Native integral thread ID of this thread, or None if it has not been started.
1085
1086 This is a non-negative integer. See the get_native_id() function.
1087 This represents the Thread ID as reported by the kernel.
1088
1089 """
1090 assert self._initialized, "Thread.__init__() not called"
1091 return self._native_id
1092
Benjamin Peterson672b8032008-06-11 19:14:14 +00001093 def is_alive(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +02001094 """Return whether the thread is alive.
1095
1096 This method returns True just before the run() method starts until just
1097 after the run() method terminates. The module function enumerate()
1098 returns a list of all alive threads.
1099
1100 """
Guido van Rossumd0648992007-08-20 19:25:41 +00001101 assert self._initialized, "Thread.__init__() not called"
Tim Petersc363a232013-09-08 18:44:40 -05001102 if self._is_stopped or not self._started.is_set():
Antoine Pitrou7b476992013-09-07 23:38:37 +02001103 return False
Antoine Pitrou7b476992013-09-07 23:38:37 +02001104 self._wait_for_tstate_lock(False)
Tim Petersc363a232013-09-08 18:44:40 -05001105 return not self._is_stopped
Tim Petersb90f89a2001-01-15 03:26:36 +00001106
Benjamin Petersonfdbea962008-08-18 17:33:47 +00001107 @property
1108 def daemon(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +02001109 """A boolean value indicating whether this thread is a daemon thread.
1110
1111 This must be set before start() is called, otherwise RuntimeError is
1112 raised. Its initial value is inherited from the creating thread; the
1113 main thread is not a daemon thread and therefore all threads created in
1114 the main thread default to daemon = False.
1115
mbarkhaubb110cc2019-06-22 14:51:06 +02001116 The entire Python program exits when only daemon threads are left.
Georg Brandlc30b59f2013-10-13 10:43:59 +02001117
1118 """
Guido van Rossumd0648992007-08-20 19:25:41 +00001119 assert self._initialized, "Thread.__init__() not called"
1120 return self._daemonic
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001121
Benjamin Petersonfdbea962008-08-18 17:33:47 +00001122 @daemon.setter
1123 def daemon(self, daemonic):
Guido van Rossumd0648992007-08-20 19:25:41 +00001124 if not self._initialized:
Guido van Rossumcd16bf62007-06-13 18:07:49 +00001125 raise RuntimeError("Thread.__init__() not called")
Benjamin Peterson672b8032008-06-11 19:14:14 +00001126 if self._started.is_set():
Antoine Pitrou10959072014-03-17 18:22:41 +01001127 raise RuntimeError("cannot set daemon status of active thread")
Guido van Rossumd0648992007-08-20 19:25:41 +00001128 self._daemonic = daemonic
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001129
Benjamin Peterson6640d722008-08-18 18:16:46 +00001130 def isDaemon(self):
1131 return self.daemon
1132
1133 def setDaemon(self, daemonic):
1134 self.daemon = daemonic
1135
1136 def getName(self):
1137 return self.name
1138
1139 def setName(self, name):
1140 self.name = name
1141
Victor Stinnercd590a72019-05-28 00:39:52 +02001142
1143try:
1144 from _thread import (_excepthook as excepthook,
1145 _ExceptHookArgs as ExceptHookArgs)
1146except ImportError:
1147 # Simple Python implementation if _thread._excepthook() is not available
1148 from traceback import print_exception as _print_exception
1149 from collections import namedtuple
1150
1151 _ExceptHookArgs = namedtuple(
1152 'ExceptHookArgs',
1153 'exc_type exc_value exc_traceback thread')
1154
1155 def ExceptHookArgs(args):
1156 return _ExceptHookArgs(*args)
1157
1158 def excepthook(args, /):
1159 """
1160 Handle uncaught Thread.run() exception.
1161 """
1162 if args.exc_type == SystemExit:
1163 # silently ignore SystemExit
1164 return
1165
1166 if _sys is not None and _sys.stderr is not None:
1167 stderr = _sys.stderr
1168 elif args.thread is not None:
1169 stderr = args.thread._stderr
1170 if stderr is None:
1171 # do nothing if sys.stderr is None and sys.stderr was None
1172 # when the thread was created
1173 return
1174 else:
1175 # do nothing if sys.stderr is None and args.thread is None
1176 return
1177
1178 if args.thread is not None:
1179 name = args.thread.name
1180 else:
1181 name = get_ident()
1182 print(f"Exception in thread {name}:",
1183 file=stderr, flush=True)
1184 _print_exception(args.exc_type, args.exc_value, args.exc_traceback,
1185 file=stderr)
1186 stderr.flush()
1187
1188
1189def _make_invoke_excepthook():
1190 # Create a local namespace to ensure that variables remain alive
1191 # when _invoke_excepthook() is called, even if it is called late during
1192 # Python shutdown. It is mostly needed for daemon threads.
1193
1194 old_excepthook = excepthook
1195 old_sys_excepthook = _sys.excepthook
1196 if old_excepthook is None:
1197 raise RuntimeError("threading.excepthook is None")
1198 if old_sys_excepthook is None:
1199 raise RuntimeError("sys.excepthook is None")
1200
1201 sys_exc_info = _sys.exc_info
1202 local_print = print
1203 local_sys = _sys
1204
1205 def invoke_excepthook(thread):
1206 global excepthook
1207 try:
1208 hook = excepthook
1209 if hook is None:
1210 hook = old_excepthook
1211
1212 args = ExceptHookArgs([*sys_exc_info(), thread])
1213
1214 hook(args)
1215 except Exception as exc:
1216 exc.__suppress_context__ = True
1217 del exc
1218
1219 if local_sys is not None and local_sys.stderr is not None:
1220 stderr = local_sys.stderr
1221 else:
1222 stderr = thread._stderr
1223
1224 local_print("Exception in threading.excepthook:",
1225 file=stderr, flush=True)
1226
1227 if local_sys is not None and local_sys.excepthook is not None:
1228 sys_excepthook = local_sys.excepthook
1229 else:
1230 sys_excepthook = old_sys_excepthook
1231
1232 sys_excepthook(*sys_exc_info())
1233 finally:
1234 # Break reference cycle (exception stored in a variable)
1235 args = None
1236
1237 return invoke_excepthook
1238
1239
Martin v. Löwis44f86962001-09-05 13:44:54 +00001240# The timer class was contributed by Itamar Shtull-Trauring
1241
Éric Araujo0cdd4452011-07-28 00:28:28 +02001242class Timer(Thread):
Martin v. Löwis44f86962001-09-05 13:44:54 +00001243 """Call a function after a specified number of seconds:
Tim Petersb64bec32001-09-18 02:26:39 +00001244
Georg Brandlc30b59f2013-10-13 10:43:59 +02001245 t = Timer(30.0, f, args=None, kwargs=None)
1246 t.start()
1247 t.cancel() # stop the timer's action if it's still waiting
1248
Martin v. Löwis44f86962001-09-05 13:44:54 +00001249 """
Tim Petersb64bec32001-09-18 02:26:39 +00001250
R David Murray19aeb432013-03-30 17:19:38 -04001251 def __init__(self, interval, function, args=None, kwargs=None):
Martin v. Löwis44f86962001-09-05 13:44:54 +00001252 Thread.__init__(self)
1253 self.interval = interval
1254 self.function = function
R David Murray19aeb432013-03-30 17:19:38 -04001255 self.args = args if args is not None else []
1256 self.kwargs = kwargs if kwargs is not None else {}
Martin v. Löwis44f86962001-09-05 13:44:54 +00001257 self.finished = Event()
Tim Petersb64bec32001-09-18 02:26:39 +00001258
Martin v. Löwis44f86962001-09-05 13:44:54 +00001259 def cancel(self):
Georg Brandlc30b59f2013-10-13 10:43:59 +02001260 """Stop the timer if it hasn't finished yet."""
Martin v. Löwis44f86962001-09-05 13:44:54 +00001261 self.finished.set()
Tim Petersb64bec32001-09-18 02:26:39 +00001262
Martin v. Löwis44f86962001-09-05 13:44:54 +00001263 def run(self):
1264 self.finished.wait(self.interval)
Benjamin Peterson672b8032008-06-11 19:14:14 +00001265 if not self.finished.is_set():
Martin v. Löwis44f86962001-09-05 13:44:54 +00001266 self.function(*self.args, **self.kwargs)
1267 self.finished.set()
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001268
Antoine Pitrou1023dbb2017-10-02 16:42:15 +02001269
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001270# Special thread class to represent the main thread
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001271
1272class _MainThread(Thread):
1273
1274 def __init__(self):
Antoine Pitrou0bd4deb2011-02-25 22:07:43 +00001275 Thread.__init__(self, name="MainThread", daemon=False)
Tim Petersc363a232013-09-08 18:44:40 -05001276 self._set_tstate_lock()
Christian Heimes9e7f1d22008-02-28 12:27:11 +00001277 self._started.set()
Benjamin Petersond23f8222009-04-05 19:13:16 +00001278 self._set_ident()
Jake Teslerb121f632019-05-22 08:43:17 -07001279 if _HAVE_THREAD_NATIVE_ID:
1280 self._set_native_id()
Benjamin Petersond23f8222009-04-05 19:13:16 +00001281 with _active_limbo_lock:
1282 _active[self._ident] = self
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001283
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001284
1285# Dummy thread class to represent threads not started here.
Tim Peters711906e2005-01-08 07:30:42 +00001286# These aren't garbage collected when they die, nor can they be waited for.
Benjamin Peterson672b8032008-06-11 19:14:14 +00001287# If they invoke anything in threading.py that calls current_thread(), they
Tim Peters711906e2005-01-08 07:30:42 +00001288# leave an entry in the _active dict forever after.
Benjamin Peterson672b8032008-06-11 19:14:14 +00001289# Their purpose is to return *something* from current_thread().
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001290# They are marked as daemon threads so we won't wait for them
1291# when we exit (conform previous semantics).
1292
1293class _DummyThread(Thread):
Tim Petersb90f89a2001-01-15 03:26:36 +00001294
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001295 def __init__(self):
Antoine Pitrou0bd4deb2011-02-25 22:07:43 +00001296 Thread.__init__(self, name=_newname("Dummy-%d"), daemon=True)
Tim Peters711906e2005-01-08 07:30:42 +00001297
Christian Heimes9e7f1d22008-02-28 12:27:11 +00001298 self._started.set()
Benjamin Petersond23f8222009-04-05 19:13:16 +00001299 self._set_ident()
Jake Teslerb121f632019-05-22 08:43:17 -07001300 if _HAVE_THREAD_NATIVE_ID:
1301 self._set_native_id()
Benjamin Petersond23f8222009-04-05 19:13:16 +00001302 with _active_limbo_lock:
1303 _active[self._ident] = self
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001304
Antoine Pitrou8e6e0fd2012-04-19 23:55:01 +02001305 def _stop(self):
1306 pass
1307
Xiang Zhangf3a9fab2017-02-27 11:01:30 +08001308 def is_alive(self):
1309 assert not self._is_stopped and self._started.is_set()
1310 return True
1311
Neal Norwitz45bec8c2002-02-19 03:01:36 +00001312 def join(self, timeout=None):
Guido van Rossum8ca162f2002-04-07 06:36:23 +00001313 assert False, "cannot join a dummy thread"
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001314
1315
1316# Global API functions
1317
Benjamin Peterson672b8032008-06-11 19:14:14 +00001318def current_thread():
Georg Brandlc30b59f2013-10-13 10:43:59 +02001319 """Return the current Thread object, corresponding to the caller's thread of control.
1320
1321 If the caller's thread of control was not created through the threading
1322 module, a dummy thread object with limited functionality is returned.
1323
1324 """
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001325 try:
Victor Stinner2a129742011-05-30 23:02:52 +02001326 return _active[get_ident()]
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001327 except KeyError:
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001328 return _DummyThread()
1329
Benjamin Petersonb3085c92008-09-01 23:09:31 +00001330currentThread = current_thread
Benjamin Petersonf0923f52008-08-18 22:10:13 +00001331
Benjamin Peterson672b8032008-06-11 19:14:14 +00001332def active_count():
Georg Brandlc30b59f2013-10-13 10:43:59 +02001333 """Return the number of Thread objects currently alive.
1334
1335 The returned count is equal to the length of the list returned by
1336 enumerate().
1337
1338 """
Benjamin Petersond23f8222009-04-05 19:13:16 +00001339 with _active_limbo_lock:
1340 return len(_active) + len(_limbo)
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001341
Benjamin Petersonb3085c92008-09-01 23:09:31 +00001342activeCount = active_count
Benjamin Petersonf0923f52008-08-18 22:10:13 +00001343
Antoine Pitroubdec11f2009-11-05 13:49:14 +00001344def _enumerate():
1345 # Same as enumerate(), but without the lock. Internal use only.
1346 return list(_active.values()) + list(_limbo.values())
1347
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001348def enumerate():
Georg Brandlc30b59f2013-10-13 10:43:59 +02001349 """Return a list of all Thread objects currently alive.
1350
1351 The list includes daemonic threads, dummy thread objects created by
1352 current_thread(), and the main thread. It excludes terminated threads and
1353 threads that have not yet been started.
1354
1355 """
Benjamin Petersond23f8222009-04-05 19:13:16 +00001356 with _active_limbo_lock:
1357 return list(_active.values()) + list(_limbo.values())
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001358
Kyle Stanleyb61b8182020-03-27 15:31:22 -04001359
1360_threading_atexits = []
1361_SHUTTING_DOWN = False
1362
1363def _register_atexit(func, *arg, **kwargs):
1364 """CPython internal: register *func* to be called before joining threads.
1365
1366 The registered *func* is called with its arguments just before all
1367 non-daemon threads are joined in `_shutdown()`. It provides a similar
1368 purpose to `atexit.register()`, but its functions are called prior to
1369 threading shutdown instead of interpreter shutdown.
1370
1371 For similarity to atexit, the registered functions are called in reverse.
1372 """
1373 if _SHUTTING_DOWN:
1374 raise RuntimeError("can't register atexit after shutdown")
1375
1376 call = functools.partial(func, *arg, **kwargs)
1377 _threading_atexits.append(call)
1378
1379
Georg Brandl2067bfd2008-05-25 13:05:15 +00001380from _thread import stack_size
Thomas Wouters0e3f5912006-08-11 14:57:12 +00001381
Thomas Wouters902d6eb2007-01-09 23:18:33 +00001382# Create the main thread object,
1383# and make it available for the interpreter
1384# (Py_Main) as threading._shutdown.
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001385
Andrew Svetlov58b5c5a2013-09-04 07:01:07 +03001386_main_thread = _MainThread()
1387
1388def _shutdown():
Victor Stinner468e5fe2019-06-13 01:30:17 +02001389 """
1390 Wait until the Python thread state of all non-daemon threads get deleted.
1391 """
Tim Petersc363a232013-09-08 18:44:40 -05001392 # Obscure: other threads may be waiting to join _main_thread. That's
1393 # dubious, but some code does it. We can't wait for C code to release
1394 # the main thread's tstate_lock - that won't happen until the interpreter
1395 # is nearly dead. So we release it here. Note that just calling _stop()
1396 # isn't enough: other threads may already be waiting on _tstate_lock.
Antoine Pitrouee84a602017-08-16 20:53:28 +02001397 if _main_thread._is_stopped:
1398 # _shutdown() was already called
1399 return
Victor Stinner468e5fe2019-06-13 01:30:17 +02001400
Kyle Stanleyb61b8182020-03-27 15:31:22 -04001401 global _SHUTTING_DOWN
1402 _SHUTTING_DOWN = True
Victor Stinner468e5fe2019-06-13 01:30:17 +02001403 # Main thread
Tim Petersb5e9ac92013-09-09 14:41:50 -05001404 tlock = _main_thread._tstate_lock
1405 # The main thread isn't finished yet, so its thread state lock can't have
1406 # been released.
1407 assert tlock is not None
1408 assert tlock.locked()
1409 tlock.release()
Andrew Svetlov58b5c5a2013-09-04 07:01:07 +03001410 _main_thread._stop()
Andrew Svetlov58b5c5a2013-09-04 07:01:07 +03001411
Kyle Stanleyb61b8182020-03-27 15:31:22 -04001412 # Call registered threading atexit functions before threads are joined.
1413 # Order is reversed, similar to atexit.
1414 for atexit_call in reversed(_threading_atexits):
1415 atexit_call()
1416
Victor Stinner468e5fe2019-06-13 01:30:17 +02001417 # Join all non-deamon threads
1418 while True:
1419 with _shutdown_locks_lock:
1420 locks = list(_shutdown_locks)
1421 _shutdown_locks.clear()
1422
1423 if not locks:
1424 break
1425
1426 for lock in locks:
1427 # mimick Thread.join()
1428 lock.acquire()
1429 lock.release()
1430
1431 # new threads can be spawned while we were waiting for the other
1432 # threads to complete
1433
Andrew Svetlov58b5c5a2013-09-04 07:01:07 +03001434
1435def main_thread():
Andrew Svetlovb1dd5572013-09-04 10:33:11 +03001436 """Return the main thread object.
1437
1438 In normal conditions, the main thread is the thread from which the
1439 Python interpreter was started.
1440 """
Andrew Svetlov58b5c5a2013-09-04 07:01:07 +03001441 return _main_thread
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001442
Jim Fultond15dc062004-07-14 19:11:50 +00001443# get thread-local implementation, either from the thread
1444# module, or from the python fallback
1445
1446try:
Georg Brandl2067bfd2008-05-25 13:05:15 +00001447 from _thread import _local as local
Brett Cannoncd171c82013-07-04 17:43:24 -04001448except ImportError:
Jim Fultond15dc062004-07-14 19:11:50 +00001449 from _threading_local import local
1450
Guido van Rossum7f5013a1998-04-09 22:01:42 +00001451
Jesse Nollera8513972008-07-17 16:49:17 +00001452def _after_fork():
Antoine Pitrou4a8bcdf2017-05-28 14:02:26 +02001453 """
1454 Cleanup threading module state that should not exist after a fork.
1455 """
Jesse Nollera8513972008-07-17 16:49:17 +00001456 # Reset _active_limbo_lock, in case we forked while the lock was held
1457 # by another (non-forked) thread. http://bugs.python.org/issue874900
Andrew Svetlov58b5c5a2013-09-04 07:01:07 +03001458 global _active_limbo_lock, _main_thread
Victor Stinner468e5fe2019-06-13 01:30:17 +02001459 global _shutdown_locks_lock, _shutdown_locks
Jesse Nollera8513972008-07-17 16:49:17 +00001460 _active_limbo_lock = _allocate_lock()
1461
1462 # fork() only copied the current thread; clear references to others.
1463 new_active = {}
Victor Stinnerd8ff44c2020-03-27 17:50:42 +01001464
1465 try:
1466 current = _active[get_ident()]
1467 except KeyError:
1468 # fork() was called in a thread which was not spawned
1469 # by threading.Thread. For example, a thread spawned
1470 # by thread.start_new_thread().
1471 current = _MainThread()
1472
Andrew Svetlov58b5c5a2013-09-04 07:01:07 +03001473 _main_thread = current
Victor Stinner468e5fe2019-06-13 01:30:17 +02001474
1475 # reset _shutdown() locks: threads re-register their _tstate_lock below
1476 _shutdown_locks_lock = _allocate_lock()
1477 _shutdown_locks = set()
1478
Jesse Nollera8513972008-07-17 16:49:17 +00001479 with _active_limbo_lock:
Antoine Pitrou5da7e792013-09-08 13:19:06 +02001480 # Dangling thread instances must still have their locks reset,
1481 # because someone may join() them.
1482 threads = set(_enumerate())
1483 threads.update(_dangling)
1484 for thread in threads:
Charles-François Natalib055bf62011-12-18 18:45:16 +01001485 # Any lock/condition variable may be currently locked or in an
1486 # invalid state, so we reinitialize them.
Jesse Nollera8513972008-07-17 16:49:17 +00001487 if thread is current:
Antoine Pitrou5fe291f2008-09-06 23:00:03 +00001488 # There is only one active thread. We reset the ident to
1489 # its new value since it can have changed.
Antoine Pitrou7b476992013-09-07 23:38:37 +02001490 thread._reset_internal_locks(True)
Victor Stinner2a129742011-05-30 23:02:52 +02001491 ident = get_ident()
Antoine Pitrou5fe291f2008-09-06 23:00:03 +00001492 thread._ident = ident
Jesse Nollera8513972008-07-17 16:49:17 +00001493 new_active[ident] = thread
1494 else:
1495 # All the others are already stopped.
Antoine Pitrou7b476992013-09-07 23:38:37 +02001496 thread._reset_internal_locks(False)
Charles-François Natalib055bf62011-12-18 18:45:16 +01001497 thread._stop()
Jesse Nollera8513972008-07-17 16:49:17 +00001498
1499 _limbo.clear()
1500 _active.clear()
1501 _active.update(new_active)
1502 assert len(_active) == 1
Antoine Pitrou4a8bcdf2017-05-28 14:02:26 +02001503
1504
Gregory P. Smith163468a2017-05-29 10:03:41 -07001505if hasattr(_os, "register_at_fork"):
1506 _os.register_at_fork(after_in_child=_after_fork)