Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/threading.py: 4%
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« prev ^ index » next coverage.py v7.0.1, created at 2022-12-25 06:11 +0000
1"""Thread module emulating a subset of Java's threading model."""
3import os as _os
4import sys as _sys
5import _thread
7from time import monotonic as _time
8from _weakrefset import WeakSet
9from itertools import islice as _islice, count as _count
10try:
11 from _collections import deque as _deque
12except ImportError:
13 from collections import deque as _deque
15# Note regarding PEP 8 compliant names
16# This threading model was originally inspired by Java, and inherited
17# the convention of camelCase function and method names from that
18# language. Those original names are not in any imminent danger of
19# being deprecated (even for Py3k),so this module provides them as an
20# alias for the PEP 8 compliant names
21# Note that using the new PEP 8 compliant names facilitates substitution
22# with the multiprocessing module, which doesn't provide the old
23# Java inspired names.
25__all__ = ['get_ident', 'active_count', 'Condition', 'current_thread',
26 'enumerate', 'main_thread', 'TIMEOUT_MAX',
27 'Event', 'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore', 'Thread',
28 'Barrier', 'BrokenBarrierError', 'Timer', 'ThreadError',
29 'setprofile', 'settrace', 'local', 'stack_size',
30 'excepthook', 'ExceptHookArgs']
32# Rename some stuff so "from threading import *" is safe
33_start_new_thread = _thread.start_new_thread
34_allocate_lock = _thread.allocate_lock
35_set_sentinel = _thread._set_sentinel
36get_ident = _thread.get_ident
37try:
38 get_native_id = _thread.get_native_id
39 _HAVE_THREAD_NATIVE_ID = True
40 __all__.append('get_native_id')
41except AttributeError:
42 _HAVE_THREAD_NATIVE_ID = False
43ThreadError = _thread.error
44try:
45 _CRLock = _thread.RLock
46except AttributeError:
47 _CRLock = None
48TIMEOUT_MAX = _thread.TIMEOUT_MAX
49del _thread
52# Support for profile and trace hooks
54_profile_hook = None
55_trace_hook = None
57def setprofile(func):
58 """Set a profile function for all threads started from the threading module.
60 The func will be passed to sys.setprofile() for each thread, before its
61 run() method is called.
63 """
64 global _profile_hook
65 _profile_hook = func
67def settrace(func):
68 """Set a trace function for all threads started from the threading module.
70 The func will be passed to sys.settrace() for each thread, before its run()
71 method is called.
73 """
74 global _trace_hook
75 _trace_hook = func
77# Synchronization classes
79Lock = _allocate_lock
81def RLock(*args, **kwargs):
82 """Factory function that returns a new reentrant lock.
84 A reentrant lock must be released by the thread that acquired it. Once a
85 thread has acquired a reentrant lock, the same thread may acquire it again
86 without blocking; the thread must release it once for each time it has
87 acquired it.
89 """
90 if _CRLock is None:
91 return _PyRLock(*args, **kwargs)
92 return _CRLock(*args, **kwargs)
94class _RLock:
95 """This class implements reentrant lock objects.
97 A reentrant lock must be released by the thread that acquired it. Once a
98 thread has acquired a reentrant lock, the same thread may acquire it
99 again without blocking; the thread must release it once for each time it
100 has acquired it.
102 """
104 def __init__(self):
105 self._block = _allocate_lock()
106 self._owner = None
107 self._count = 0
109 def __repr__(self):
110 owner = self._owner
111 try:
112 owner = _active[owner].name
113 except KeyError:
114 pass
115 return "<%s %s.%s object owner=%r count=%d at %s>" % (
116 "locked" if self._block.locked() else "unlocked",
117 self.__class__.__module__,
118 self.__class__.__qualname__,
119 owner,
120 self._count,
121 hex(id(self))
122 )
124 def acquire(self, blocking=True, timeout=-1):
125 """Acquire a lock, blocking or non-blocking.
127 When invoked without arguments: if this thread already owns the lock,
128 increment the recursion level by one, and return immediately. Otherwise,
129 if another thread owns the lock, block until the lock is unlocked. Once
130 the lock is unlocked (not owned by any thread), then grab ownership, set
131 the recursion level to one, and return. If more than one thread is
132 blocked waiting until the lock is unlocked, only one at a time will be
133 able to grab ownership of the lock. There is no return value in this
134 case.
136 When invoked with the blocking argument set to true, do the same thing
137 as when called without arguments, and return true.
139 When invoked with the blocking argument set to false, do not block. If a
140 call without an argument would block, return false immediately;
141 otherwise, do the same thing as when called without arguments, and
142 return true.
144 When invoked with the floating-point timeout argument set to a positive
145 value, block for at most the number of seconds specified by timeout
146 and as long as the lock cannot be acquired. Return true if the lock has
147 been acquired, false if the timeout has elapsed.
149 """
150 me = get_ident()
151 if self._owner == me:
152 self._count += 1
153 return 1
154 rc = self._block.acquire(blocking, timeout)
155 if rc:
156 self._owner = me
157 self._count = 1
158 return rc
160 __enter__ = acquire
162 def release(self):
163 """Release a lock, decrementing the recursion level.
165 If after the decrement it is zero, reset the lock to unlocked (not owned
166 by any thread), and if any other threads are blocked waiting for the
167 lock to become unlocked, allow exactly one of them to proceed. If after
168 the decrement the recursion level is still nonzero, the lock remains
169 locked and owned by the calling thread.
171 Only call this method when the calling thread owns the lock. A
172 RuntimeError is raised if this method is called when the lock is
173 unlocked.
175 There is no return value.
177 """
178 if self._owner != get_ident():
179 raise RuntimeError("cannot release un-acquired lock")
180 self._count = count = self._count - 1
181 if not count:
182 self._owner = None
183 self._block.release()
185 def __exit__(self, t, v, tb):
186 self.release()
188 # Internal methods used by condition variables
190 def _acquire_restore(self, state):
191 self._block.acquire()
192 self._count, self._owner = state
194 def _release_save(self):
195 if self._count == 0:
196 raise RuntimeError("cannot release un-acquired lock")
197 count = self._count
198 self._count = 0
199 owner = self._owner
200 self._owner = None
201 self._block.release()
202 return (count, owner)
204 def _is_owned(self):
205 return self._owner == get_ident()
207_PyRLock = _RLock
210class Condition:
211 """Class that implements a condition variable.
213 A condition variable allows one or more threads to wait until they are
214 notified by another thread.
216 If the lock argument is given and not None, it must be a Lock or RLock
217 object, and it is used as the underlying lock. Otherwise, a new RLock object
218 is created and used as the underlying lock.
220 """
222 def __init__(self, lock=None):
223 if lock is None:
224 lock = RLock()
225 self._lock = lock
226 # Export the lock's acquire() and release() methods
227 self.acquire = lock.acquire
228 self.release = lock.release
229 # If the lock defines _release_save() and/or _acquire_restore(),
230 # these override the default implementations (which just call
231 # release() and acquire() on the lock). Ditto for _is_owned().
232 try:
233 self._release_save = lock._release_save
234 except AttributeError:
235 pass
236 try:
237 self._acquire_restore = lock._acquire_restore
238 except AttributeError:
239 pass
240 try:
241 self._is_owned = lock._is_owned
242 except AttributeError:
243 pass
244 self._waiters = _deque()
246 def __enter__(self):
247 return self._lock.__enter__()
249 def __exit__(self, *args):
250 return self._lock.__exit__(*args)
252 def __repr__(self):
253 return "<Condition(%s, %d)>" % (self._lock, len(self._waiters))
255 def _release_save(self):
256 self._lock.release() # No state to save
258 def _acquire_restore(self, x):
259 self._lock.acquire() # Ignore saved state
261 def _is_owned(self):
262 # Return True if lock is owned by current_thread.
263 # This method is called only if _lock doesn't have _is_owned().
264 if self._lock.acquire(0):
265 self._lock.release()
266 return False
267 else:
268 return True
270 def wait(self, timeout=None):
271 """Wait until notified or until a timeout occurs.
273 If the calling thread has not acquired the lock when this method is
274 called, a RuntimeError is raised.
276 This method releases the underlying lock, and then blocks until it is
277 awakened by a notify() or notify_all() call for the same condition
278 variable in another thread, or until the optional timeout occurs. Once
279 awakened or timed out, it re-acquires the lock and returns.
281 When the timeout argument is present and not None, it should be a
282 floating point number specifying a timeout for the operation in seconds
283 (or fractions thereof).
285 When the underlying lock is an RLock, it is not released using its
286 release() method, since this may not actually unlock the lock when it
287 was acquired multiple times recursively. Instead, an internal interface
288 of the RLock class is used, which really unlocks it even when it has
289 been recursively acquired several times. Another internal interface is
290 then used to restore the recursion level when the lock is reacquired.
292 """
293 if not self._is_owned():
294 raise RuntimeError("cannot wait on un-acquired lock")
295 waiter = _allocate_lock()
296 waiter.acquire()
297 self._waiters.append(waiter)
298 saved_state = self._release_save()
299 gotit = False
300 try: # restore state no matter what (e.g., KeyboardInterrupt)
301 if timeout is None:
302 waiter.acquire()
303 gotit = True
304 else:
305 if timeout > 0:
306 gotit = waiter.acquire(True, timeout)
307 else:
308 gotit = waiter.acquire(False)
309 return gotit
310 finally:
311 self._acquire_restore(saved_state)
312 if not gotit:
313 try:
314 self._waiters.remove(waiter)
315 except ValueError:
316 pass
318 def wait_for(self, predicate, timeout=None):
319 """Wait until a condition evaluates to True.
321 predicate should be a callable which result will be interpreted as a
322 boolean value. A timeout may be provided giving the maximum time to
323 wait.
325 """
326 endtime = None
327 waittime = timeout
328 result = predicate()
329 while not result:
330 if waittime is not None:
331 if endtime is None:
332 endtime = _time() + waittime
333 else:
334 waittime = endtime - _time()
335 if waittime <= 0:
336 break
337 self.wait(waittime)
338 result = predicate()
339 return result
341 def notify(self, n=1):
342 """Wake up one or more threads waiting on this condition, if any.
344 If the calling thread has not acquired the lock when this method is
345 called, a RuntimeError is raised.
347 This method wakes up at most n of the threads waiting for the condition
348 variable; it is a no-op if no threads are waiting.
350 """
351 if not self._is_owned():
352 raise RuntimeError("cannot notify on un-acquired lock")
353 all_waiters = self._waiters
354 waiters_to_notify = _deque(_islice(all_waiters, n))
355 if not waiters_to_notify:
356 return
357 for waiter in waiters_to_notify:
358 waiter.release()
359 try:
360 all_waiters.remove(waiter)
361 except ValueError:
362 pass
364 def notify_all(self):
365 """Wake up all threads waiting on this condition.
367 If the calling thread has not acquired the lock when this method
368 is called, a RuntimeError is raised.
370 """
371 self.notify(len(self._waiters))
373 notifyAll = notify_all
376class Semaphore:
377 """This class implements semaphore objects.
379 Semaphores manage a counter representing the number of release() calls minus
380 the number of acquire() calls, plus an initial value. The acquire() method
381 blocks if necessary until it can return without making the counter
382 negative. If not given, value defaults to 1.
384 """
386 # After Tim Peters' semaphore class, but not quite the same (no maximum)
388 def __init__(self, value=1):
389 if value < 0:
390 raise ValueError("semaphore initial value must be >= 0")
391 self._cond = Condition(Lock())
392 self._value = value
394 def acquire(self, blocking=True, timeout=None):
395 """Acquire a semaphore, decrementing the internal counter by one.
397 When invoked without arguments: if the internal counter is larger than
398 zero on entry, decrement it by one and return immediately. If it is zero
399 on entry, block, waiting until some other thread has called release() to
400 make it larger than zero. This is done with proper interlocking so that
401 if multiple acquire() calls are blocked, release() will wake exactly one
402 of them up. The implementation may pick one at random, so the order in
403 which blocked threads are awakened should not be relied on. There is no
404 return value in this case.
406 When invoked with blocking set to true, do the same thing as when called
407 without arguments, and return true.
409 When invoked with blocking set to false, do not block. If a call without
410 an argument would block, return false immediately; otherwise, do the
411 same thing as when called without arguments, and return true.
413 When invoked with a timeout other than None, it will block for at
414 most timeout seconds. If acquire does not complete successfully in
415 that interval, return false. Return true otherwise.
417 """
418 if not blocking and timeout is not None:
419 raise ValueError("can't specify timeout for non-blocking acquire")
420 rc = False
421 endtime = None
422 with self._cond:
423 while self._value == 0:
424 if not blocking:
425 break
426 if timeout is not None:
427 if endtime is None:
428 endtime = _time() + timeout
429 else:
430 timeout = endtime - _time()
431 if timeout <= 0:
432 break
433 self._cond.wait(timeout)
434 else:
435 self._value -= 1
436 rc = True
437 return rc
439 __enter__ = acquire
441 def release(self):
442 """Release a semaphore, incrementing the internal counter by one.
444 When the counter is zero on entry and another thread is waiting for it
445 to become larger than zero again, wake up that thread.
447 """
448 with self._cond:
449 self._value += 1
450 self._cond.notify()
452 def __exit__(self, t, v, tb):
453 self.release()
456class BoundedSemaphore(Semaphore):
457 """Implements a bounded semaphore.
459 A bounded semaphore checks to make sure its current value doesn't exceed its
460 initial value. If it does, ValueError is raised. In most situations
461 semaphores are used to guard resources with limited capacity.
463 If the semaphore is released too many times it's a sign of a bug. If not
464 given, value defaults to 1.
466 Like regular semaphores, bounded semaphores manage a counter representing
467 the number of release() calls minus the number of acquire() calls, plus an
468 initial value. The acquire() method blocks if necessary until it can return
469 without making the counter negative. If not given, value defaults to 1.
471 """
473 def __init__(self, value=1):
474 Semaphore.__init__(self, value)
475 self._initial_value = value
477 def release(self):
478 """Release a semaphore, incrementing the internal counter by one.
480 When the counter is zero on entry and another thread is waiting for it
481 to become larger than zero again, wake up that thread.
483 If the number of releases exceeds the number of acquires,
484 raise a ValueError.
486 """
487 with self._cond:
488 if self._value >= self._initial_value:
489 raise ValueError("Semaphore released too many times")
490 self._value += 1
491 self._cond.notify()
494class Event:
495 """Class implementing event objects.
497 Events manage a flag that can be set to true with the set() method and reset
498 to false with the clear() method. The wait() method blocks until the flag is
499 true. The flag is initially false.
501 """
503 # After Tim Peters' event class (without is_posted())
505 def __init__(self):
506 self._cond = Condition(Lock())
507 self._flag = False
509 def _reset_internal_locks(self):
510 # private! called by Thread._reset_internal_locks by _after_fork()
511 self._cond.__init__(Lock())
513 def is_set(self):
514 """Return true if and only if the internal flag is true."""
515 return self._flag
517 isSet = is_set
519 def set(self):
520 """Set the internal flag to true.
522 All threads waiting for it to become true are awakened. Threads
523 that call wait() once the flag is true will not block at all.
525 """
526 with self._cond:
527 self._flag = True
528 self._cond.notify_all()
530 def clear(self):
531 """Reset the internal flag to false.
533 Subsequently, threads calling wait() will block until set() is called to
534 set the internal flag to true again.
536 """
537 with self._cond:
538 self._flag = False
540 def wait(self, timeout=None):
541 """Block until the internal flag is true.
543 If the internal flag is true on entry, return immediately. Otherwise,
544 block until another thread calls set() to set the flag to true, or until
545 the optional timeout occurs.
547 When the timeout argument is present and not None, it should be a
548 floating point number specifying a timeout for the operation in seconds
549 (or fractions thereof).
551 This method returns the internal flag on exit, so it will always return
552 True except if a timeout is given and the operation times out.
554 """
555 with self._cond:
556 signaled = self._flag
557 if not signaled:
558 signaled = self._cond.wait(timeout)
559 return signaled
562# A barrier class. Inspired in part by the pthread_barrier_* api and
563# the CyclicBarrier class from Java. See
564# http://sourceware.org/pthreads-win32/manual/pthread_barrier_init.html and
565# http://java.sun.com/j2se/1.5.0/docs/api/java/util/concurrent/
566# CyclicBarrier.html
567# for information.
568# We maintain two main states, 'filling' and 'draining' enabling the barrier
569# to be cyclic. Threads are not allowed into it until it has fully drained
570# since the previous cycle. In addition, a 'resetting' state exists which is
571# similar to 'draining' except that threads leave with a BrokenBarrierError,
572# and a 'broken' state in which all threads get the exception.
573class Barrier:
574 """Implements a Barrier.
576 Useful for synchronizing a fixed number of threads at known synchronization
577 points. Threads block on 'wait()' and are simultaneously awoken once they
578 have all made that call.
580 """
582 def __init__(self, parties, action=None, timeout=None):
583 """Create a barrier, initialised to 'parties' threads.
585 'action' is a callable which, when supplied, will be called by one of
586 the threads after they have all entered the barrier and just prior to
587 releasing them all. If a 'timeout' is provided, it is used as the
588 default for all subsequent 'wait()' calls.
590 """
591 self._cond = Condition(Lock())
592 self._action = action
593 self._timeout = timeout
594 self._parties = parties
595 self._state = 0 #0 filling, 1, draining, -1 resetting, -2 broken
596 self._count = 0
598 def wait(self, timeout=None):
599 """Wait for the barrier.
601 When the specified number of threads have started waiting, they are all
602 simultaneously awoken. If an 'action' was provided for the barrier, one
603 of the threads will have executed that callback prior to returning.
604 Returns an individual index number from 0 to 'parties-1'.
606 """
607 if timeout is None:
608 timeout = self._timeout
609 with self._cond:
610 self._enter() # Block while the barrier drains.
611 index = self._count
612 self._count += 1
613 try:
614 if index + 1 == self._parties:
615 # We release the barrier
616 self._release()
617 else:
618 # We wait until someone releases us
619 self._wait(timeout)
620 return index
621 finally:
622 self._count -= 1
623 # Wake up any threads waiting for barrier to drain.
624 self._exit()
626 # Block until the barrier is ready for us, or raise an exception
627 # if it is broken.
628 def _enter(self):
629 while self._state in (-1, 1):
630 # It is draining or resetting, wait until done
631 self._cond.wait()
632 #see if the barrier is in a broken state
633 if self._state < 0:
634 raise BrokenBarrierError
635 assert self._state == 0
637 # Optionally run the 'action' and release the threads waiting
638 # in the barrier.
639 def _release(self):
640 try:
641 if self._action:
642 self._action()
643 # enter draining state
644 self._state = 1
645 self._cond.notify_all()
646 except:
647 #an exception during the _action handler. Break and reraise
648 self._break()
649 raise
651 # Wait in the barrier until we are released. Raise an exception
652 # if the barrier is reset or broken.
653 def _wait(self, timeout):
654 if not self._cond.wait_for(lambda : self._state != 0, timeout):
655 #timed out. Break the barrier
656 self._break()
657 raise BrokenBarrierError
658 if self._state < 0:
659 raise BrokenBarrierError
660 assert self._state == 1
662 # If we are the last thread to exit the barrier, signal any threads
663 # waiting for the barrier to drain.
664 def _exit(self):
665 if self._count == 0:
666 if self._state in (-1, 1):
667 #resetting or draining
668 self._state = 0
669 self._cond.notify_all()
671 def reset(self):
672 """Reset the barrier to the initial state.
674 Any threads currently waiting will get the BrokenBarrier exception
675 raised.
677 """
678 with self._cond:
679 if self._count > 0:
680 if self._state == 0:
681 #reset the barrier, waking up threads
682 self._state = -1
683 elif self._state == -2:
684 #was broken, set it to reset state
685 #which clears when the last thread exits
686 self._state = -1
687 else:
688 self._state = 0
689 self._cond.notify_all()
691 def abort(self):
692 """Place the barrier into a 'broken' state.
694 Useful in case of error. Any currently waiting threads and threads
695 attempting to 'wait()' will have BrokenBarrierError raised.
697 """
698 with self._cond:
699 self._break()
701 def _break(self):
702 # An internal error was detected. The barrier is set to
703 # a broken state all parties awakened.
704 self._state = -2
705 self._cond.notify_all()
707 @property
708 def parties(self):
709 """Return the number of threads required to trip the barrier."""
710 return self._parties
712 @property
713 def n_waiting(self):
714 """Return the number of threads currently waiting at the barrier."""
715 # We don't need synchronization here since this is an ephemeral result
716 # anyway. It returns the correct value in the steady state.
717 if self._state == 0:
718 return self._count
719 return 0
721 @property
722 def broken(self):
723 """Return True if the barrier is in a broken state."""
724 return self._state == -2
726# exception raised by the Barrier class
727class BrokenBarrierError(RuntimeError):
728 pass
731# Helper to generate new thread names
732_counter = _count().__next__
733_counter() # Consume 0 so first non-main thread has id 1.
734def _newname(template="Thread-%d"):
735 return template % _counter()
737# Active thread administration
738_active_limbo_lock = _allocate_lock()
739_active = {} # maps thread id to Thread object
740_limbo = {}
741_dangling = WeakSet()
742# Set of Thread._tstate_lock locks of non-daemon threads used by _shutdown()
743# to wait until all Python thread states get deleted:
744# see Thread._set_tstate_lock().
745_shutdown_locks_lock = _allocate_lock()
746_shutdown_locks = set()
748# Main class for threads
750class Thread:
751 """A class that represents a thread of control.
753 This class can be safely subclassed in a limited fashion. There are two ways
754 to specify the activity: by passing a callable object to the constructor, or
755 by overriding the run() method in a subclass.
757 """
759 _initialized = False
761 def __init__(self, group=None, target=None, name=None,
762 args=(), kwargs=None, *, daemon=None):
763 """This constructor should always be called with keyword arguments. Arguments are:
765 *group* should be None; reserved for future extension when a ThreadGroup
766 class is implemented.
768 *target* is the callable object to be invoked by the run()
769 method. Defaults to None, meaning nothing is called.
771 *name* is the thread name. By default, a unique name is constructed of
772 the form "Thread-N" where N is a small decimal number.
774 *args* is the argument tuple for the target invocation. Defaults to ().
776 *kwargs* is a dictionary of keyword arguments for the target
777 invocation. Defaults to {}.
779 If a subclass overrides the constructor, it must make sure to invoke
780 the base class constructor (Thread.__init__()) before doing anything
781 else to the thread.
783 """
784 assert group is None, "group argument must be None for now"
785 if kwargs is None:
786 kwargs = {}
787 self._target = target
788 self._name = str(name or _newname())
789 self._args = args
790 self._kwargs = kwargs
791 if daemon is not None:
792 self._daemonic = daemon
793 else:
794 self._daemonic = current_thread().daemon
795 self._ident = None
796 if _HAVE_THREAD_NATIVE_ID:
797 self._native_id = None
798 self._tstate_lock = None
799 self._started = Event()
800 self._is_stopped = False
801 self._initialized = True
802 # Copy of sys.stderr used by self._invoke_excepthook()
803 self._stderr = _sys.stderr
804 self._invoke_excepthook = _make_invoke_excepthook()
805 # For debugging and _after_fork()
806 _dangling.add(self)
808 def _reset_internal_locks(self, is_alive):
809 # private! Called by _after_fork() to reset our internal locks as
810 # they may be in an invalid state leading to a deadlock or crash.
811 self._started._reset_internal_locks()
812 if is_alive:
813 self._set_tstate_lock()
814 else:
815 # The thread isn't alive after fork: it doesn't have a tstate
816 # anymore.
817 self._is_stopped = True
818 self._tstate_lock = None
820 def __repr__(self):
821 assert self._initialized, "Thread.__init__() was not called"
822 status = "initial"
823 if self._started.is_set():
824 status = "started"
825 self.is_alive() # easy way to get ._is_stopped set when appropriate
826 if self._is_stopped:
827 status = "stopped"
828 if self._daemonic:
829 status += " daemon"
830 if self._ident is not None:
831 status += " %s" % self._ident
832 return "<%s(%s, %s)>" % (self.__class__.__name__, self._name, status)
834 def start(self):
835 """Start the thread's activity.
837 It must be called at most once per thread object. It arranges for the
838 object's run() method to be invoked in a separate thread of control.
840 This method will raise a RuntimeError if called more than once on the
841 same thread object.
843 """
844 if not self._initialized:
845 raise RuntimeError("thread.__init__() not called")
847 if self._started.is_set():
848 raise RuntimeError("threads can only be started once")
849 with _active_limbo_lock:
850 _limbo[self] = self
851 try:
852 _start_new_thread(self._bootstrap, ())
853 except Exception:
854 with _active_limbo_lock:
855 del _limbo[self]
856 raise
857 self._started.wait()
859 def run(self):
860 """Method representing the thread's activity.
862 You may override this method in a subclass. The standard run() method
863 invokes the callable object passed to the object's constructor as the
864 target argument, if any, with sequential and keyword arguments taken
865 from the args and kwargs arguments, respectively.
867 """
868 try:
869 if self._target:
870 self._target(*self._args, **self._kwargs)
871 finally:
872 # Avoid a refcycle if the thread is running a function with
873 # an argument that has a member that points to the thread.
874 del self._target, self._args, self._kwargs
876 def _bootstrap(self):
877 # Wrapper around the real bootstrap code that ignores
878 # exceptions during interpreter cleanup. Those typically
879 # happen when a daemon thread wakes up at an unfortunate
880 # moment, finds the world around it destroyed, and raises some
881 # random exception *** while trying to report the exception in
882 # _bootstrap_inner() below ***. Those random exceptions
883 # don't help anybody, and they confuse users, so we suppress
884 # them. We suppress them only when it appears that the world
885 # indeed has already been destroyed, so that exceptions in
886 # _bootstrap_inner() during normal business hours are properly
887 # reported. Also, we only suppress them for daemonic threads;
888 # if a non-daemonic encounters this, something else is wrong.
889 try:
890 self._bootstrap_inner()
891 except:
892 if self._daemonic and _sys is None:
893 return
894 raise
896 def _set_ident(self):
897 self._ident = get_ident()
899 if _HAVE_THREAD_NATIVE_ID:
900 def _set_native_id(self):
901 self._native_id = get_native_id()
903 def _set_tstate_lock(self):
904 """
905 Set a lock object which will be released by the interpreter when
906 the underlying thread state (see pystate.h) gets deleted.
907 """
908 self._tstate_lock = _set_sentinel()
909 self._tstate_lock.acquire()
911 if not self.daemon:
912 with _shutdown_locks_lock:
913 _shutdown_locks.add(self._tstate_lock)
915 def _bootstrap_inner(self):
916 try:
917 self._set_ident()
918 self._set_tstate_lock()
919 if _HAVE_THREAD_NATIVE_ID:
920 self._set_native_id()
921 self._started.set()
922 with _active_limbo_lock:
923 _active[self._ident] = self
924 del _limbo[self]
926 if _trace_hook:
927 _sys.settrace(_trace_hook)
928 if _profile_hook:
929 _sys.setprofile(_profile_hook)
931 try:
932 self.run()
933 except:
934 self._invoke_excepthook(self)
935 finally:
936 with _active_limbo_lock:
937 try:
938 # We don't call self._delete() because it also
939 # grabs _active_limbo_lock.
940 del _active[get_ident()]
941 except:
942 pass
944 def _stop(self):
945 # After calling ._stop(), .is_alive() returns False and .join() returns
946 # immediately. ._tstate_lock must be released before calling ._stop().
947 #
948 # Normal case: C code at the end of the thread's life
949 # (release_sentinel in _threadmodule.c) releases ._tstate_lock, and
950 # that's detected by our ._wait_for_tstate_lock(), called by .join()
951 # and .is_alive(). Any number of threads _may_ call ._stop()
952 # simultaneously (for example, if multiple threads are blocked in
953 # .join() calls), and they're not serialized. That's harmless -
954 # they'll just make redundant rebindings of ._is_stopped and
955 # ._tstate_lock. Obscure: we rebind ._tstate_lock last so that the
956 # "assert self._is_stopped" in ._wait_for_tstate_lock() always works
957 # (the assert is executed only if ._tstate_lock is None).
958 #
959 # Special case: _main_thread releases ._tstate_lock via this
960 # module's _shutdown() function.
961 lock = self._tstate_lock
962 if lock is not None:
963 assert not lock.locked()
964 self._is_stopped = True
965 self._tstate_lock = None
966 if not self.daemon:
967 with _shutdown_locks_lock:
968 _shutdown_locks.discard(lock)
970 def _delete(self):
971 "Remove current thread from the dict of currently running threads."
972 with _active_limbo_lock:
973 del _active[get_ident()]
974 # There must not be any python code between the previous line
975 # and after the lock is released. Otherwise a tracing function
976 # could try to acquire the lock again in the same thread, (in
977 # current_thread()), and would block.
979 def join(self, timeout=None):
980 """Wait until the thread terminates.
982 This blocks the calling thread until the thread whose join() method is
983 called terminates -- either normally or through an unhandled exception
984 or until the optional timeout occurs.
986 When the timeout argument is present and not None, it should be a
987 floating point number specifying a timeout for the operation in seconds
988 (or fractions thereof). As join() always returns None, you must call
989 is_alive() after join() to decide whether a timeout happened -- if the
990 thread is still alive, the join() call timed out.
992 When the timeout argument is not present or None, the operation will
993 block until the thread terminates.
995 A thread can be join()ed many times.
997 join() raises a RuntimeError if an attempt is made to join the current
998 thread as that would cause a deadlock. It is also an error to join() a
999 thread before it has been started and attempts to do so raises the same
1000 exception.
1002 """
1003 if not self._initialized:
1004 raise RuntimeError("Thread.__init__() not called")
1005 if not self._started.is_set():
1006 raise RuntimeError("cannot join thread before it is started")
1007 if self is current_thread():
1008 raise RuntimeError("cannot join current thread")
1010 if timeout is None:
1011 self._wait_for_tstate_lock()
1012 else:
1013 # the behavior of a negative timeout isn't documented, but
1014 # historically .join(timeout=x) for x<0 has acted as if timeout=0
1015 self._wait_for_tstate_lock(timeout=max(timeout, 0))
1017 def _wait_for_tstate_lock(self, block=True, timeout=-1):
1018 # Issue #18808: wait for the thread state to be gone.
1019 # At the end of the thread's life, after all knowledge of the thread
1020 # is removed from C data structures, C code releases our _tstate_lock.
1021 # This method passes its arguments to _tstate_lock.acquire().
1022 # If the lock is acquired, the C code is done, and self._stop() is
1023 # called. That sets ._is_stopped to True, and ._tstate_lock to None.
1024 lock = self._tstate_lock
1025 if lock is None: # already determined that the C code is done
1026 assert self._is_stopped
1027 elif lock.acquire(block, timeout):
1028 lock.release()
1029 self._stop()
1031 @property
1032 def name(self):
1033 """A string used for identification purposes only.
1035 It has no semantics. Multiple threads may be given the same name. The
1036 initial name is set by the constructor.
1038 """
1039 assert self._initialized, "Thread.__init__() not called"
1040 return self._name
1042 @name.setter
1043 def name(self, name):
1044 assert self._initialized, "Thread.__init__() not called"
1045 self._name = str(name)
1047 @property
1048 def ident(self):
1049 """Thread identifier of this thread or None if it has not been started.
1051 This is a nonzero integer. See the get_ident() function. Thread
1052 identifiers may be recycled when a thread exits and another thread is
1053 created. The identifier is available even after the thread has exited.
1055 """
1056 assert self._initialized, "Thread.__init__() not called"
1057 return self._ident
1059 if _HAVE_THREAD_NATIVE_ID:
1060 @property
1061 def native_id(self):
1062 """Native integral thread ID of this thread, or None if it has not been started.
1064 This is a non-negative integer. See the get_native_id() function.
1065 This represents the Thread ID as reported by the kernel.
1067 """
1068 assert self._initialized, "Thread.__init__() not called"
1069 return self._native_id
1071 def is_alive(self):
1072 """Return whether the thread is alive.
1074 This method returns True just before the run() method starts until just
1075 after the run() method terminates. The module function enumerate()
1076 returns a list of all alive threads.
1078 """
1079 assert self._initialized, "Thread.__init__() not called"
1080 if self._is_stopped or not self._started.is_set():
1081 return False
1082 self._wait_for_tstate_lock(False)
1083 return not self._is_stopped
1085 def isAlive(self):
1086 """Return whether the thread is alive.
1088 This method is deprecated, use is_alive() instead.
1089 """
1090 import warnings
1091 warnings.warn('isAlive() is deprecated, use is_alive() instead',
1092 DeprecationWarning, stacklevel=2)
1093 return self.is_alive()
1095 @property
1096 def daemon(self):
1097 """A boolean value indicating whether this thread is a daemon thread.
1099 This must be set before start() is called, otherwise RuntimeError is
1100 raised. Its initial value is inherited from the creating thread; the
1101 main thread is not a daemon thread and therefore all threads created in
1102 the main thread default to daemon = False.
1104 The entire Python program exits when only daemon threads are left.
1106 """
1107 assert self._initialized, "Thread.__init__() not called"
1108 return self._daemonic
1110 @daemon.setter
1111 def daemon(self, daemonic):
1112 if not self._initialized:
1113 raise RuntimeError("Thread.__init__() not called")
1114 if self._started.is_set():
1115 raise RuntimeError("cannot set daemon status of active thread")
1116 self._daemonic = daemonic
1118 def isDaemon(self):
1119 return self.daemon
1121 def setDaemon(self, daemonic):
1122 self.daemon = daemonic
1124 def getName(self):
1125 return self.name
1127 def setName(self, name):
1128 self.name = name
1131try:
1132 from _thread import (_excepthook as excepthook,
1133 _ExceptHookArgs as ExceptHookArgs)
1134except ImportError:
1135 # Simple Python implementation if _thread._excepthook() is not available
1136 from traceback import print_exception as _print_exception
1137 from collections import namedtuple
1139 _ExceptHookArgs = namedtuple(
1140 'ExceptHookArgs',
1141 'exc_type exc_value exc_traceback thread')
1143 def ExceptHookArgs(args):
1144 return _ExceptHookArgs(*args)
1146 def excepthook(args, /):
1147 """
1148 Handle uncaught Thread.run() exception.
1149 """
1150 if args.exc_type == SystemExit:
1151 # silently ignore SystemExit
1152 return
1154 if _sys is not None and _sys.stderr is not None:
1155 stderr = _sys.stderr
1156 elif args.thread is not None:
1157 stderr = args.thread._stderr
1158 if stderr is None:
1159 # do nothing if sys.stderr is None and sys.stderr was None
1160 # when the thread was created
1161 return
1162 else:
1163 # do nothing if sys.stderr is None and args.thread is None
1164 return
1166 if args.thread is not None:
1167 name = args.thread.name
1168 else:
1169 name = get_ident()
1170 print(f"Exception in thread {name}:",
1171 file=stderr, flush=True)
1172 _print_exception(args.exc_type, args.exc_value, args.exc_traceback,
1173 file=stderr)
1174 stderr.flush()
1177def _make_invoke_excepthook():
1178 # Create a local namespace to ensure that variables remain alive
1179 # when _invoke_excepthook() is called, even if it is called late during
1180 # Python shutdown. It is mostly needed for daemon threads.
1182 old_excepthook = excepthook
1183 old_sys_excepthook = _sys.excepthook
1184 if old_excepthook is None:
1185 raise RuntimeError("threading.excepthook is None")
1186 if old_sys_excepthook is None:
1187 raise RuntimeError("sys.excepthook is None")
1189 sys_exc_info = _sys.exc_info
1190 local_print = print
1191 local_sys = _sys
1193 def invoke_excepthook(thread):
1194 global excepthook
1195 try:
1196 hook = excepthook
1197 if hook is None:
1198 hook = old_excepthook
1200 args = ExceptHookArgs([*sys_exc_info(), thread])
1202 hook(args)
1203 except Exception as exc:
1204 exc.__suppress_context__ = True
1205 del exc
1207 if local_sys is not None and local_sys.stderr is not None:
1208 stderr = local_sys.stderr
1209 else:
1210 stderr = thread._stderr
1212 local_print("Exception in threading.excepthook:",
1213 file=stderr, flush=True)
1215 if local_sys is not None and local_sys.excepthook is not None:
1216 sys_excepthook = local_sys.excepthook
1217 else:
1218 sys_excepthook = old_sys_excepthook
1220 sys_excepthook(*sys_exc_info())
1221 finally:
1222 # Break reference cycle (exception stored in a variable)
1223 args = None
1225 return invoke_excepthook
1228# The timer class was contributed by Itamar Shtull-Trauring
1230class Timer(Thread):
1231 """Call a function after a specified number of seconds:
1233 t = Timer(30.0, f, args=None, kwargs=None)
1234 t.start()
1235 t.cancel() # stop the timer's action if it's still waiting
1237 """
1239 def __init__(self, interval, function, args=None, kwargs=None):
1240 Thread.__init__(self)
1241 self.interval = interval
1242 self.function = function
1243 self.args = args if args is not None else []
1244 self.kwargs = kwargs if kwargs is not None else {}
1245 self.finished = Event()
1247 def cancel(self):
1248 """Stop the timer if it hasn't finished yet."""
1249 self.finished.set()
1251 def run(self):
1252 self.finished.wait(self.interval)
1253 if not self.finished.is_set():
1254 self.function(*self.args, **self.kwargs)
1255 self.finished.set()
1258# Special thread class to represent the main thread
1260class _MainThread(Thread):
1262 def __init__(self):
1263 Thread.__init__(self, name="MainThread", daemon=False)
1264 self._set_tstate_lock()
1265 self._started.set()
1266 self._set_ident()
1267 if _HAVE_THREAD_NATIVE_ID:
1268 self._set_native_id()
1269 with _active_limbo_lock:
1270 _active[self._ident] = self
1273# Dummy thread class to represent threads not started here.
1274# These aren't garbage collected when they die, nor can they be waited for.
1275# If they invoke anything in threading.py that calls current_thread(), they
1276# leave an entry in the _active dict forever after.
1277# Their purpose is to return *something* from current_thread().
1278# They are marked as daemon threads so we won't wait for them
1279# when we exit (conform previous semantics).
1281class _DummyThread(Thread):
1283 def __init__(self):
1284 Thread.__init__(self, name=_newname("Dummy-%d"), daemon=True)
1286 self._started.set()
1287 self._set_ident()
1288 if _HAVE_THREAD_NATIVE_ID:
1289 self._set_native_id()
1290 with _active_limbo_lock:
1291 _active[self._ident] = self
1293 def _stop(self):
1294 pass
1296 def is_alive(self):
1297 assert not self._is_stopped and self._started.is_set()
1298 return True
1300 def join(self, timeout=None):
1301 assert False, "cannot join a dummy thread"
1304# Global API functions
1306def current_thread():
1307 """Return the current Thread object, corresponding to the caller's thread of control.
1309 If the caller's thread of control was not created through the threading
1310 module, a dummy thread object with limited functionality is returned.
1312 """
1313 try:
1314 return _active[get_ident()]
1315 except KeyError:
1316 return _DummyThread()
1318currentThread = current_thread
1320def active_count():
1321 """Return the number of Thread objects currently alive.
1323 The returned count is equal to the length of the list returned by
1324 enumerate().
1326 """
1327 with _active_limbo_lock:
1328 return len(_active) + len(_limbo)
1330activeCount = active_count
1332def _enumerate():
1333 # Same as enumerate(), but without the lock. Internal use only.
1334 return list(_active.values()) + list(_limbo.values())
1336def enumerate():
1337 """Return a list of all Thread objects currently alive.
1339 The list includes daemonic threads, dummy thread objects created by
1340 current_thread(), and the main thread. It excludes terminated threads and
1341 threads that have not yet been started.
1343 """
1344 with _active_limbo_lock:
1345 return list(_active.values()) + list(_limbo.values())
1347from _thread import stack_size
1349# Create the main thread object,
1350# and make it available for the interpreter
1351# (Py_Main) as threading._shutdown.
1353_main_thread = _MainThread()
1355def _shutdown():
1356 """
1357 Wait until the Python thread state of all non-daemon threads get deleted.
1358 """
1359 # Obscure: other threads may be waiting to join _main_thread. That's
1360 # dubious, but some code does it. We can't wait for C code to release
1361 # the main thread's tstate_lock - that won't happen until the interpreter
1362 # is nearly dead. So we release it here. Note that just calling _stop()
1363 # isn't enough: other threads may already be waiting on _tstate_lock.
1364 if _main_thread._is_stopped:
1365 # _shutdown() was already called
1366 return
1368 # Main thread
1369 tlock = _main_thread._tstate_lock
1370 # The main thread isn't finished yet, so its thread state lock can't have
1371 # been released.
1372 assert tlock is not None
1373 assert tlock.locked()
1374 tlock.release()
1375 _main_thread._stop()
1377 # Join all non-deamon threads
1378 while True:
1379 with _shutdown_locks_lock:
1380 locks = list(_shutdown_locks)
1381 _shutdown_locks.clear()
1383 if not locks:
1384 break
1386 for lock in locks:
1387 # mimick Thread.join()
1388 lock.acquire()
1389 lock.release()
1391 # new threads can be spawned while we were waiting for the other
1392 # threads to complete
1395def main_thread():
1396 """Return the main thread object.
1398 In normal conditions, the main thread is the thread from which the
1399 Python interpreter was started.
1400 """
1401 return _main_thread
1403# get thread-local implementation, either from the thread
1404# module, or from the python fallback
1406try:
1407 from _thread import _local as local
1408except ImportError:
1409 from _threading_local import local
1412def _after_fork():
1413 """
1414 Cleanup threading module state that should not exist after a fork.
1415 """
1416 # Reset _active_limbo_lock, in case we forked while the lock was held
1417 # by another (non-forked) thread. http://bugs.python.org/issue874900
1418 global _active_limbo_lock, _main_thread
1419 global _shutdown_locks_lock, _shutdown_locks
1420 _active_limbo_lock = _allocate_lock()
1422 # fork() only copied the current thread; clear references to others.
1423 new_active = {}
1425 try:
1426 current = _active[get_ident()]
1427 except KeyError:
1428 # fork() was called in a thread which was not spawned
1429 # by threading.Thread. For example, a thread spawned
1430 # by thread.start_new_thread().
1431 current = _MainThread()
1433 _main_thread = current
1435 # reset _shutdown() locks: threads re-register their _tstate_lock below
1436 _shutdown_locks_lock = _allocate_lock()
1437 _shutdown_locks = set()
1439 with _active_limbo_lock:
1440 # Dangling thread instances must still have their locks reset,
1441 # because someone may join() them.
1442 threads = set(_enumerate())
1443 threads.update(_dangling)
1444 for thread in threads:
1445 # Any lock/condition variable may be currently locked or in an
1446 # invalid state, so we reinitialize them.
1447 if thread is current:
1448 # There is only one active thread. We reset the ident to
1449 # its new value since it can have changed.
1450 thread._reset_internal_locks(True)
1451 ident = get_ident()
1452 thread._ident = ident
1453 new_active[ident] = thread
1454 else:
1455 # All the others are already stopped.
1456 thread._reset_internal_locks(False)
1457 thread._stop()
1459 _limbo.clear()
1460 _active.clear()
1461 _active.update(new_active)
1462 assert len(_active) == 1
1465if hasattr(_os, "register_at_fork"):
1466 _os.register_at_fork(after_in_child=_after_fork)