mirror of
https://github.com/python/cpython.git
synced 2024-11-23 18:04:37 +08:00
894f2c3c16
Not comprehensive, best effort warning. There are cases when threads exist on some platforms that this code cannot detect. macOS when API permissions allow and Linux with a readable /proc procfs present are the currently supported cases where a warning should show up reliably. Starting with a DeprecationWarning for now, it is less disruptive than something like RuntimeWarning and most likely to only be seen in people's CI tests - a good place to start with this messaging.
1681 lines
58 KiB
Python
1681 lines
58 KiB
Python
"""Thread module emulating a subset of Java's threading model."""
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import os as _os
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import sys as _sys
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import _thread
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import functools
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from time import monotonic as _time
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from _weakrefset import WeakSet
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from itertools import count as _count
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try:
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from _collections import deque as _deque
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except ImportError:
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from collections import deque as _deque
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# Note regarding PEP 8 compliant names
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# This threading model was originally inspired by Java, and inherited
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# the convention of camelCase function and method names from that
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# language. Those original names are not in any imminent danger of
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# being deprecated (even for Py3k),so this module provides them as an
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# alias for the PEP 8 compliant names
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# Note that using the new PEP 8 compliant names facilitates substitution
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# with the multiprocessing module, which doesn't provide the old
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# Java inspired names.
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__all__ = ['get_ident', 'active_count', 'Condition', 'current_thread',
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'enumerate', 'main_thread', 'TIMEOUT_MAX',
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'Event', 'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore', 'Thread',
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'Barrier', 'BrokenBarrierError', 'Timer', 'ThreadError',
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'setprofile', 'settrace', 'local', 'stack_size',
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'excepthook', 'ExceptHookArgs', 'gettrace', 'getprofile',
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'setprofile_all_threads','settrace_all_threads']
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# Rename some stuff so "from threading import *" is safe
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_start_new_thread = _thread.start_new_thread
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_daemon_threads_allowed = _thread.daemon_threads_allowed
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_allocate_lock = _thread.allocate_lock
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_set_sentinel = _thread._set_sentinel
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get_ident = _thread.get_ident
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try:
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get_native_id = _thread.get_native_id
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_HAVE_THREAD_NATIVE_ID = True
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__all__.append('get_native_id')
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except AttributeError:
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_HAVE_THREAD_NATIVE_ID = False
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ThreadError = _thread.error
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try:
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_CRLock = _thread.RLock
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except AttributeError:
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_CRLock = None
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TIMEOUT_MAX = _thread.TIMEOUT_MAX
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del _thread
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# Support for profile and trace hooks
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_profile_hook = None
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_trace_hook = None
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def setprofile(func):
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"""Set a profile function for all threads started from the threading module.
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The func will be passed to sys.setprofile() for each thread, before its
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run() method is called.
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"""
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global _profile_hook
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_profile_hook = func
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def setprofile_all_threads(func):
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"""Set a profile function for all threads started from the threading module
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and all Python threads that are currently executing.
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The func will be passed to sys.setprofile() for each thread, before its
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run() method is called.
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"""
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setprofile(func)
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_sys._setprofileallthreads(func)
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def getprofile():
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"""Get the profiler function as set by threading.setprofile()."""
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return _profile_hook
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def settrace(func):
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"""Set a trace function for all threads started from the threading module.
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The func will be passed to sys.settrace() for each thread, before its run()
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method is called.
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"""
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global _trace_hook
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_trace_hook = func
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def settrace_all_threads(func):
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"""Set a trace function for all threads started from the threading module
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and all Python threads that are currently executing.
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The func will be passed to sys.settrace() for each thread, before its run()
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method is called.
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"""
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settrace(func)
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_sys._settraceallthreads(func)
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def gettrace():
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"""Get the trace function as set by threading.settrace()."""
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return _trace_hook
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# Synchronization classes
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Lock = _allocate_lock
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def RLock(*args, **kwargs):
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"""Factory function that returns a new reentrant lock.
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A reentrant lock must be released by the thread that acquired it. Once a
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thread has acquired a reentrant lock, the same thread may acquire it again
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without blocking; the thread must release it once for each time it has
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acquired it.
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"""
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if _CRLock is None:
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return _PyRLock(*args, **kwargs)
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return _CRLock(*args, **kwargs)
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class _RLock:
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"""This class implements reentrant lock objects.
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A reentrant lock must be released by the thread that acquired it. Once a
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thread has acquired a reentrant lock, the same thread may acquire it
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again without blocking; the thread must release it once for each time it
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has acquired it.
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"""
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def __init__(self):
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self._block = _allocate_lock()
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self._owner = None
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self._count = 0
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def __repr__(self):
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owner = self._owner
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try:
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owner = _active[owner].name
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except KeyError:
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pass
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return "<%s %s.%s object owner=%r count=%d at %s>" % (
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"locked" if self._block.locked() else "unlocked",
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self.__class__.__module__,
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self.__class__.__qualname__,
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owner,
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self._count,
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hex(id(self))
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)
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def _at_fork_reinit(self):
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self._block._at_fork_reinit()
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self._owner = None
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self._count = 0
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def acquire(self, blocking=True, timeout=-1):
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"""Acquire a lock, blocking or non-blocking.
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When invoked without arguments: if this thread already owns the lock,
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increment the recursion level by one, and return immediately. Otherwise,
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if another thread owns the lock, block until the lock is unlocked. Once
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the lock is unlocked (not owned by any thread), then grab ownership, set
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the recursion level to one, and return. If more than one thread is
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blocked waiting until the lock is unlocked, only one at a time will be
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able to grab ownership of the lock. There is no return value in this
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case.
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When invoked with the blocking argument set to true, do the same thing
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as when called without arguments, and return true.
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When invoked with the blocking argument set to false, do not block. If a
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call without an argument would block, return false immediately;
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otherwise, do the same thing as when called without arguments, and
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return true.
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When invoked with the floating-point timeout argument set to a positive
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value, block for at most the number of seconds specified by timeout
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and as long as the lock cannot be acquired. Return true if the lock has
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been acquired, false if the timeout has elapsed.
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"""
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me = get_ident()
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if self._owner == me:
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self._count += 1
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return 1
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rc = self._block.acquire(blocking, timeout)
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if rc:
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self._owner = me
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self._count = 1
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return rc
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__enter__ = acquire
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def release(self):
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"""Release a lock, decrementing the recursion level.
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If after the decrement it is zero, reset the lock to unlocked (not owned
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by any thread), and if any other threads are blocked waiting for the
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lock to become unlocked, allow exactly one of them to proceed. If after
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the decrement the recursion level is still nonzero, the lock remains
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locked and owned by the calling thread.
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Only call this method when the calling thread owns the lock. A
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RuntimeError is raised if this method is called when the lock is
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unlocked.
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There is no return value.
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"""
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if self._owner != get_ident():
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raise RuntimeError("cannot release un-acquired lock")
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self._count = count = self._count - 1
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if not count:
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self._owner = None
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self._block.release()
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def __exit__(self, t, v, tb):
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self.release()
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# Internal methods used by condition variables
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def _acquire_restore(self, state):
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self._block.acquire()
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self._count, self._owner = state
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def _release_save(self):
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if self._count == 0:
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raise RuntimeError("cannot release un-acquired lock")
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count = self._count
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self._count = 0
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owner = self._owner
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self._owner = None
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self._block.release()
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return (count, owner)
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def _is_owned(self):
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return self._owner == get_ident()
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_PyRLock = _RLock
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class Condition:
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"""Class that implements a condition variable.
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A condition variable allows one or more threads to wait until they are
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notified by another thread.
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If the lock argument is given and not None, it must be a Lock or RLock
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object, and it is used as the underlying lock. Otherwise, a new RLock object
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is created and used as the underlying lock.
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"""
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def __init__(self, lock=None):
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if lock is None:
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lock = RLock()
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self._lock = lock
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# Export the lock's acquire() and release() methods
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self.acquire = lock.acquire
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self.release = lock.release
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# If the lock defines _release_save() and/or _acquire_restore(),
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# these override the default implementations (which just call
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# release() and acquire() on the lock). Ditto for _is_owned().
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if hasattr(lock, '_release_save'):
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self._release_save = lock._release_save
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if hasattr(lock, '_acquire_restore'):
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self._acquire_restore = lock._acquire_restore
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if hasattr(lock, '_is_owned'):
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self._is_owned = lock._is_owned
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self._waiters = _deque()
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def _at_fork_reinit(self):
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self._lock._at_fork_reinit()
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self._waiters.clear()
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def __enter__(self):
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return self._lock.__enter__()
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def __exit__(self, *args):
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return self._lock.__exit__(*args)
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def __repr__(self):
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return "<Condition(%s, %d)>" % (self._lock, len(self._waiters))
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def _release_save(self):
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self._lock.release() # No state to save
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def _acquire_restore(self, x):
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self._lock.acquire() # Ignore saved state
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def _is_owned(self):
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# Return True if lock is owned by current_thread.
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# This method is called only if _lock doesn't have _is_owned().
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if self._lock.acquire(False):
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self._lock.release()
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return False
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else:
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return True
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def wait(self, timeout=None):
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"""Wait until notified or until a timeout occurs.
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If the calling thread has not acquired the lock when this method is
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called, a RuntimeError is raised.
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This method releases the underlying lock, and then blocks until it is
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awakened by a notify() or notify_all() call for the same condition
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variable in another thread, or until the optional timeout occurs. Once
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awakened or timed out, it re-acquires the lock and returns.
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When the timeout argument is present and not None, it should be a
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floating point number specifying a timeout for the operation in seconds
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(or fractions thereof).
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When the underlying lock is an RLock, it is not released using its
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release() method, since this may not actually unlock the lock when it
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was acquired multiple times recursively. Instead, an internal interface
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of the RLock class is used, which really unlocks it even when it has
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been recursively acquired several times. Another internal interface is
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then used to restore the recursion level when the lock is reacquired.
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"""
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if not self._is_owned():
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raise RuntimeError("cannot wait on un-acquired lock")
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waiter = _allocate_lock()
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waiter.acquire()
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self._waiters.append(waiter)
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saved_state = self._release_save()
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gotit = False
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try: # restore state no matter what (e.g., KeyboardInterrupt)
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if timeout is None:
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waiter.acquire()
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gotit = True
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else:
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if timeout > 0:
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gotit = waiter.acquire(True, timeout)
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else:
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gotit = waiter.acquire(False)
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return gotit
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finally:
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self._acquire_restore(saved_state)
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if not gotit:
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try:
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self._waiters.remove(waiter)
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except ValueError:
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pass
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def wait_for(self, predicate, timeout=None):
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"""Wait until a condition evaluates to True.
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predicate should be a callable which result will be interpreted as a
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boolean value. A timeout may be provided giving the maximum time to
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wait.
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"""
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endtime = None
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waittime = timeout
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result = predicate()
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while not result:
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if waittime is not None:
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if endtime is None:
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endtime = _time() + waittime
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else:
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waittime = endtime - _time()
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if waittime <= 0:
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break
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self.wait(waittime)
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result = predicate()
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return result
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def notify(self, n=1):
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"""Wake up one or more threads waiting on this condition, if any.
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If the calling thread has not acquired the lock when this method is
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called, a RuntimeError is raised.
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This method wakes up at most n of the threads waiting for the condition
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variable; it is a no-op if no threads are waiting.
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"""
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if not self._is_owned():
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raise RuntimeError("cannot notify on un-acquired lock")
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waiters = self._waiters
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while waiters and n > 0:
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waiter = waiters[0]
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try:
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waiter.release()
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except RuntimeError:
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# gh-92530: The previous call of notify() released the lock,
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# but was interrupted before removing it from the queue.
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# It can happen if a signal handler raises an exception,
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# like CTRL+C which raises KeyboardInterrupt.
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pass
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else:
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n -= 1
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try:
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waiters.remove(waiter)
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except ValueError:
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pass
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def notify_all(self):
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"""Wake up all threads waiting on this condition.
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If the calling thread has not acquired the lock when this method
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is called, a RuntimeError is raised.
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"""
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self.notify(len(self._waiters))
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def notifyAll(self):
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"""Wake up all threads waiting on this condition.
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This method is deprecated, use notify_all() instead.
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"""
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import warnings
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warnings.warn('notifyAll() is deprecated, use notify_all() instead',
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DeprecationWarning, stacklevel=2)
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self.notify_all()
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class Semaphore:
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"""This class implements semaphore objects.
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Semaphores manage a counter representing the number of release() calls minus
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the number of acquire() calls, plus an initial value. The acquire() method
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blocks if necessary until it can return without making the counter
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negative. If not given, value defaults to 1.
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"""
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# After Tim Peters' semaphore class, but not quite the same (no maximum)
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def __init__(self, value=1):
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if value < 0:
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raise ValueError("semaphore initial value must be >= 0")
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self._cond = Condition(Lock())
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self._value = value
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def __repr__(self):
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cls = self.__class__
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return (f"<{cls.__module__}.{cls.__qualname__} at {id(self):#x}:"
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f" value={self._value}>")
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def acquire(self, blocking=True, timeout=None):
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"""Acquire a semaphore, decrementing the internal counter by one.
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When invoked without arguments: if the internal counter is larger than
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zero on entry, decrement it by one and return immediately. If it is zero
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on entry, block, waiting until some other thread has called release() to
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make it larger than zero. This is done with proper interlocking so that
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if multiple acquire() calls are blocked, release() will wake exactly one
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of them up. The implementation may pick one at random, so the order in
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which blocked threads are awakened should not be relied on. There is no
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return value in this case.
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When invoked with blocking set to true, do the same thing as when called
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without arguments, and return true.
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When invoked with blocking set to false, do not block. If a call without
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an argument would block, return false immediately; otherwise, do the
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same thing as when called without arguments, and return true.
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When invoked with a timeout other than None, it will block for at
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most timeout seconds. If acquire does not complete successfully in
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that interval, return false. Return true otherwise.
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"""
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if not blocking and timeout is not None:
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raise ValueError("can't specify timeout for non-blocking acquire")
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rc = False
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endtime = None
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with self._cond:
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while self._value == 0:
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if not blocking:
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break
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if timeout is not None:
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if endtime is None:
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endtime = _time() + timeout
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else:
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timeout = endtime - _time()
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if timeout <= 0:
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break
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self._cond.wait(timeout)
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else:
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self._value -= 1
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rc = True
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return rc
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__enter__ = acquire
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def release(self, n=1):
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"""Release a semaphore, incrementing the internal counter by one or more.
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When the counter is zero on entry and another thread is waiting for it
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to become larger than zero again, wake up that thread.
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"""
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if n < 1:
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raise ValueError('n must be one or more')
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with self._cond:
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self._value += n
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self._cond.notify(n)
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|
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def __exit__(self, t, v, tb):
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self.release()
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|
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|
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class BoundedSemaphore(Semaphore):
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"""Implements a bounded semaphore.
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A bounded semaphore checks to make sure its current value doesn't exceed its
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initial value. If it does, ValueError is raised. In most situations
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semaphores are used to guard resources with limited capacity.
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If the semaphore is released too many times it's a sign of a bug. If not
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given, value defaults to 1.
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Like regular semaphores, bounded semaphores manage a counter representing
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the number of release() calls minus the number of acquire() calls, plus an
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initial value. The acquire() method blocks if necessary until it can return
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without making the counter negative. If not given, value defaults to 1.
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"""
|
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|
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def __init__(self, value=1):
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super().__init__(value)
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self._initial_value = value
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|
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def __repr__(self):
|
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cls = self.__class__
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return (f"<{cls.__module__}.{cls.__qualname__} at {id(self):#x}:"
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f" value={self._value}/{self._initial_value}>")
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|
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def release(self, n=1):
|
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"""Release a semaphore, incrementing the internal counter by one or more.
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|
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When the counter is zero on entry and another thread is waiting for it
|
|
to become larger than zero again, wake up that thread.
|
|
|
|
If the number of releases exceeds the number of acquires,
|
|
raise a ValueError.
|
|
|
|
"""
|
|
if n < 1:
|
|
raise ValueError('n must be one or more')
|
|
with self._cond:
|
|
if self._value + n > self._initial_value:
|
|
raise ValueError("Semaphore released too many times")
|
|
self._value += n
|
|
self._cond.notify(n)
|
|
|
|
|
|
class Event:
|
|
"""Class implementing event objects.
|
|
|
|
Events manage a flag that can be set to true with the set() method and reset
|
|
to false with the clear() method. The wait() method blocks until the flag is
|
|
true. The flag is initially false.
|
|
|
|
"""
|
|
|
|
# After Tim Peters' event class (without is_posted())
|
|
|
|
def __init__(self):
|
|
self._cond = Condition(Lock())
|
|
self._flag = False
|
|
|
|
def __repr__(self):
|
|
cls = self.__class__
|
|
status = 'set' if self._flag else 'unset'
|
|
return f"<{cls.__module__}.{cls.__qualname__} at {id(self):#x}: {status}>"
|
|
|
|
def _at_fork_reinit(self):
|
|
# Private method called by Thread._reset_internal_locks()
|
|
self._cond._at_fork_reinit()
|
|
|
|
def is_set(self):
|
|
"""Return true if and only if the internal flag is true."""
|
|
return self._flag
|
|
|
|
def isSet(self):
|
|
"""Return true if and only if the internal flag is true.
|
|
|
|
This method is deprecated, use is_set() instead.
|
|
|
|
"""
|
|
import warnings
|
|
warnings.warn('isSet() is deprecated, use is_set() instead',
|
|
DeprecationWarning, stacklevel=2)
|
|
return self.is_set()
|
|
|
|
def set(self):
|
|
"""Set the internal flag to true.
|
|
|
|
All threads waiting for it to become true are awakened. Threads
|
|
that call wait() once the flag is true will not block at all.
|
|
|
|
"""
|
|
with self._cond:
|
|
self._flag = True
|
|
self._cond.notify_all()
|
|
|
|
def clear(self):
|
|
"""Reset the internal flag to false.
|
|
|
|
Subsequently, threads calling wait() will block until set() is called to
|
|
set the internal flag to true again.
|
|
|
|
"""
|
|
with self._cond:
|
|
self._flag = False
|
|
|
|
def wait(self, timeout=None):
|
|
"""Block until the internal flag is true.
|
|
|
|
If the internal flag is true on entry, return immediately. Otherwise,
|
|
block until another thread calls set() to set the flag to true, or until
|
|
the optional timeout occurs.
|
|
|
|
When the timeout argument is present and not None, it should be a
|
|
floating point number specifying a timeout for the operation in seconds
|
|
(or fractions thereof).
|
|
|
|
This method returns the internal flag on exit, so it will always return
|
|
True except if a timeout is given and the operation times out.
|
|
|
|
"""
|
|
with self._cond:
|
|
signaled = self._flag
|
|
if not signaled:
|
|
signaled = self._cond.wait(timeout)
|
|
return signaled
|
|
|
|
|
|
# A barrier class. Inspired in part by the pthread_barrier_* api and
|
|
# the CyclicBarrier class from Java. See
|
|
# http://sourceware.org/pthreads-win32/manual/pthread_barrier_init.html and
|
|
# http://java.sun.com/j2se/1.5.0/docs/api/java/util/concurrent/
|
|
# CyclicBarrier.html
|
|
# for information.
|
|
# We maintain two main states, 'filling' and 'draining' enabling the barrier
|
|
# to be cyclic. Threads are not allowed into it until it has fully drained
|
|
# since the previous cycle. In addition, a 'resetting' state exists which is
|
|
# similar to 'draining' except that threads leave with a BrokenBarrierError,
|
|
# and a 'broken' state in which all threads get the exception.
|
|
class Barrier:
|
|
"""Implements a Barrier.
|
|
|
|
Useful for synchronizing a fixed number of threads at known synchronization
|
|
points. Threads block on 'wait()' and are simultaneously awoken once they
|
|
have all made that call.
|
|
|
|
"""
|
|
|
|
def __init__(self, parties, action=None, timeout=None):
|
|
"""Create a barrier, initialised to 'parties' threads.
|
|
|
|
'action' is a callable which, when supplied, will be called by one of
|
|
the threads after they have all entered the barrier and just prior to
|
|
releasing them all. If a 'timeout' is provided, it is used as the
|
|
default for all subsequent 'wait()' calls.
|
|
|
|
"""
|
|
self._cond = Condition(Lock())
|
|
self._action = action
|
|
self._timeout = timeout
|
|
self._parties = parties
|
|
self._state = 0 # 0 filling, 1 draining, -1 resetting, -2 broken
|
|
self._count = 0
|
|
|
|
def __repr__(self):
|
|
cls = self.__class__
|
|
if self.broken:
|
|
return f"<{cls.__module__}.{cls.__qualname__} at {id(self):#x}: broken>"
|
|
return (f"<{cls.__module__}.{cls.__qualname__} at {id(self):#x}:"
|
|
f" waiters={self.n_waiting}/{self.parties}>")
|
|
|
|
def wait(self, timeout=None):
|
|
"""Wait for the barrier.
|
|
|
|
When the specified number of threads have started waiting, they are all
|
|
simultaneously awoken. If an 'action' was provided for the barrier, one
|
|
of the threads will have executed that callback prior to returning.
|
|
Returns an individual index number from 0 to 'parties-1'.
|
|
|
|
"""
|
|
if timeout is None:
|
|
timeout = self._timeout
|
|
with self._cond:
|
|
self._enter() # Block while the barrier drains.
|
|
index = self._count
|
|
self._count += 1
|
|
try:
|
|
if index + 1 == self._parties:
|
|
# We release the barrier
|
|
self._release()
|
|
else:
|
|
# We wait until someone releases us
|
|
self._wait(timeout)
|
|
return index
|
|
finally:
|
|
self._count -= 1
|
|
# Wake up any threads waiting for barrier to drain.
|
|
self._exit()
|
|
|
|
# Block until the barrier is ready for us, or raise an exception
|
|
# if it is broken.
|
|
def _enter(self):
|
|
while self._state in (-1, 1):
|
|
# It is draining or resetting, wait until done
|
|
self._cond.wait()
|
|
#see if the barrier is in a broken state
|
|
if self._state < 0:
|
|
raise BrokenBarrierError
|
|
assert self._state == 0
|
|
|
|
# Optionally run the 'action' and release the threads waiting
|
|
# in the barrier.
|
|
def _release(self):
|
|
try:
|
|
if self._action:
|
|
self._action()
|
|
# enter draining state
|
|
self._state = 1
|
|
self._cond.notify_all()
|
|
except:
|
|
#an exception during the _action handler. Break and reraise
|
|
self._break()
|
|
raise
|
|
|
|
# Wait in the barrier until we are released. Raise an exception
|
|
# if the barrier is reset or broken.
|
|
def _wait(self, timeout):
|
|
if not self._cond.wait_for(lambda : self._state != 0, timeout):
|
|
#timed out. Break the barrier
|
|
self._break()
|
|
raise BrokenBarrierError
|
|
if self._state < 0:
|
|
raise BrokenBarrierError
|
|
assert self._state == 1
|
|
|
|
# If we are the last thread to exit the barrier, signal any threads
|
|
# waiting for the barrier to drain.
|
|
def _exit(self):
|
|
if self._count == 0:
|
|
if self._state in (-1, 1):
|
|
#resetting or draining
|
|
self._state = 0
|
|
self._cond.notify_all()
|
|
|
|
def reset(self):
|
|
"""Reset the barrier to the initial state.
|
|
|
|
Any threads currently waiting will get the BrokenBarrier exception
|
|
raised.
|
|
|
|
"""
|
|
with self._cond:
|
|
if self._count > 0:
|
|
if self._state == 0:
|
|
#reset the barrier, waking up threads
|
|
self._state = -1
|
|
elif self._state == -2:
|
|
#was broken, set it to reset state
|
|
#which clears when the last thread exits
|
|
self._state = -1
|
|
else:
|
|
self._state = 0
|
|
self._cond.notify_all()
|
|
|
|
def abort(self):
|
|
"""Place the barrier into a 'broken' state.
|
|
|
|
Useful in case of error. Any currently waiting threads and threads
|
|
attempting to 'wait()' will have BrokenBarrierError raised.
|
|
|
|
"""
|
|
with self._cond:
|
|
self._break()
|
|
|
|
def _break(self):
|
|
# An internal error was detected. The barrier is set to
|
|
# a broken state all parties awakened.
|
|
self._state = -2
|
|
self._cond.notify_all()
|
|
|
|
@property
|
|
def parties(self):
|
|
"""Return the number of threads required to trip the barrier."""
|
|
return self._parties
|
|
|
|
@property
|
|
def n_waiting(self):
|
|
"""Return the number of threads currently waiting at the barrier."""
|
|
# We don't need synchronization here since this is an ephemeral result
|
|
# anyway. It returns the correct value in the steady state.
|
|
if self._state == 0:
|
|
return self._count
|
|
return 0
|
|
|
|
@property
|
|
def broken(self):
|
|
"""Return True if the barrier is in a broken state."""
|
|
return self._state == -2
|
|
|
|
# exception raised by the Barrier class
|
|
class BrokenBarrierError(RuntimeError):
|
|
pass
|
|
|
|
|
|
# Helper to generate new thread names
|
|
_counter = _count(1).__next__
|
|
def _newname(name_template):
|
|
return name_template % _counter()
|
|
|
|
# Active thread administration.
|
|
#
|
|
# bpo-44422: Use a reentrant lock to allow reentrant calls to functions like
|
|
# threading.enumerate().
|
|
_active_limbo_lock = RLock()
|
|
_active = {} # maps thread id to Thread object
|
|
_limbo = {}
|
|
_dangling = WeakSet()
|
|
|
|
# Set of Thread._tstate_lock locks of non-daemon threads used by _shutdown()
|
|
# to wait until all Python thread states get deleted:
|
|
# see Thread._set_tstate_lock().
|
|
_shutdown_locks_lock = _allocate_lock()
|
|
_shutdown_locks = set()
|
|
|
|
def _maintain_shutdown_locks():
|
|
"""
|
|
Drop any shutdown locks that don't correspond to running threads anymore.
|
|
|
|
Calling this from time to time avoids an ever-growing _shutdown_locks
|
|
set when Thread objects are not joined explicitly. See bpo-37788.
|
|
|
|
This must be called with _shutdown_locks_lock acquired.
|
|
"""
|
|
# If a lock was released, the corresponding thread has exited
|
|
to_remove = [lock for lock in _shutdown_locks if not lock.locked()]
|
|
_shutdown_locks.difference_update(to_remove)
|
|
|
|
|
|
# Main class for threads
|
|
|
|
class Thread:
|
|
"""A class that represents a thread of control.
|
|
|
|
This class can be safely subclassed in a limited fashion. There are two ways
|
|
to specify the activity: by passing a callable object to the constructor, or
|
|
by overriding the run() method in a subclass.
|
|
|
|
"""
|
|
|
|
_initialized = False
|
|
|
|
def __init__(self, group=None, target=None, name=None,
|
|
args=(), kwargs=None, *, daemon=None):
|
|
"""This constructor should always be called with keyword arguments. Arguments are:
|
|
|
|
*group* should be None; reserved for future extension when a ThreadGroup
|
|
class is implemented.
|
|
|
|
*target* is the callable object to be invoked by the run()
|
|
method. Defaults to None, meaning nothing is called.
|
|
|
|
*name* is the thread name. By default, a unique name is constructed of
|
|
the form "Thread-N" where N is a small decimal number.
|
|
|
|
*args* is a list or tuple of arguments for the target invocation. Defaults to ().
|
|
|
|
*kwargs* is a dictionary of keyword arguments for the target
|
|
invocation. Defaults to {}.
|
|
|
|
If a subclass overrides the constructor, it must make sure to invoke
|
|
the base class constructor (Thread.__init__()) before doing anything
|
|
else to the thread.
|
|
|
|
"""
|
|
assert group is None, "group argument must be None for now"
|
|
if kwargs is None:
|
|
kwargs = {}
|
|
if name:
|
|
name = str(name)
|
|
else:
|
|
name = _newname("Thread-%d")
|
|
if target is not None:
|
|
try:
|
|
target_name = target.__name__
|
|
name += f" ({target_name})"
|
|
except AttributeError:
|
|
pass
|
|
|
|
self._target = target
|
|
self._name = name
|
|
self._args = args
|
|
self._kwargs = kwargs
|
|
if daemon is not None:
|
|
if daemon and not _daemon_threads_allowed():
|
|
raise RuntimeError('daemon threads are disabled in this (sub)interpreter')
|
|
self._daemonic = daemon
|
|
else:
|
|
self._daemonic = current_thread().daemon
|
|
self._ident = None
|
|
if _HAVE_THREAD_NATIVE_ID:
|
|
self._native_id = None
|
|
self._tstate_lock = None
|
|
self._started = Event()
|
|
self._is_stopped = False
|
|
self._initialized = True
|
|
# Copy of sys.stderr used by self._invoke_excepthook()
|
|
self._stderr = _sys.stderr
|
|
self._invoke_excepthook = _make_invoke_excepthook()
|
|
# For debugging and _after_fork()
|
|
_dangling.add(self)
|
|
|
|
def _reset_internal_locks(self, is_alive):
|
|
# private! Called by _after_fork() to reset our internal locks as
|
|
# they may be in an invalid state leading to a deadlock or crash.
|
|
self._started._at_fork_reinit()
|
|
if is_alive:
|
|
# bpo-42350: If the fork happens when the thread is already stopped
|
|
# (ex: after threading._shutdown() has been called), _tstate_lock
|
|
# is None. Do nothing in this case.
|
|
if self._tstate_lock is not None:
|
|
self._tstate_lock._at_fork_reinit()
|
|
self._tstate_lock.acquire()
|
|
else:
|
|
# The thread isn't alive after fork: it doesn't have a tstate
|
|
# anymore.
|
|
self._is_stopped = True
|
|
self._tstate_lock = None
|
|
|
|
def __repr__(self):
|
|
assert self._initialized, "Thread.__init__() was not called"
|
|
status = "initial"
|
|
if self._started.is_set():
|
|
status = "started"
|
|
self.is_alive() # easy way to get ._is_stopped set when appropriate
|
|
if self._is_stopped:
|
|
status = "stopped"
|
|
if self._daemonic:
|
|
status += " daemon"
|
|
if self._ident is not None:
|
|
status += " %s" % self._ident
|
|
return "<%s(%s, %s)>" % (self.__class__.__name__, self._name, status)
|
|
|
|
def start(self):
|
|
"""Start the thread's activity.
|
|
|
|
It must be called at most once per thread object. It arranges for the
|
|
object's run() method to be invoked in a separate thread of control.
|
|
|
|
This method will raise a RuntimeError if called more than once on the
|
|
same thread object.
|
|
|
|
"""
|
|
if not self._initialized:
|
|
raise RuntimeError("thread.__init__() not called")
|
|
|
|
if self._started.is_set():
|
|
raise RuntimeError("threads can only be started once")
|
|
|
|
with _active_limbo_lock:
|
|
_limbo[self] = self
|
|
try:
|
|
_start_new_thread(self._bootstrap, ())
|
|
except Exception:
|
|
with _active_limbo_lock:
|
|
del _limbo[self]
|
|
raise
|
|
self._started.wait()
|
|
|
|
def run(self):
|
|
"""Method representing the thread's activity.
|
|
|
|
You may override this method in a subclass. The standard run() method
|
|
invokes the callable object passed to the object's constructor as the
|
|
target argument, if any, with sequential and keyword arguments taken
|
|
from the args and kwargs arguments, respectively.
|
|
|
|
"""
|
|
try:
|
|
if self._target is not None:
|
|
self._target(*self._args, **self._kwargs)
|
|
finally:
|
|
# Avoid a refcycle if the thread is running a function with
|
|
# an argument that has a member that points to the thread.
|
|
del self._target, self._args, self._kwargs
|
|
|
|
def _bootstrap(self):
|
|
# Wrapper around the real bootstrap code that ignores
|
|
# exceptions during interpreter cleanup. Those typically
|
|
# happen when a daemon thread wakes up at an unfortunate
|
|
# moment, finds the world around it destroyed, and raises some
|
|
# random exception *** while trying to report the exception in
|
|
# _bootstrap_inner() below ***. Those random exceptions
|
|
# don't help anybody, and they confuse users, so we suppress
|
|
# them. We suppress them only when it appears that the world
|
|
# indeed has already been destroyed, so that exceptions in
|
|
# _bootstrap_inner() during normal business hours are properly
|
|
# reported. Also, we only suppress them for daemonic threads;
|
|
# if a non-daemonic encounters this, something else is wrong.
|
|
try:
|
|
self._bootstrap_inner()
|
|
except:
|
|
if self._daemonic and _sys is None:
|
|
return
|
|
raise
|
|
|
|
def _set_ident(self):
|
|
self._ident = get_ident()
|
|
|
|
if _HAVE_THREAD_NATIVE_ID:
|
|
def _set_native_id(self):
|
|
self._native_id = get_native_id()
|
|
|
|
def _set_tstate_lock(self):
|
|
"""
|
|
Set a lock object which will be released by the interpreter when
|
|
the underlying thread state (see pystate.h) gets deleted.
|
|
"""
|
|
self._tstate_lock = _set_sentinel()
|
|
self._tstate_lock.acquire()
|
|
|
|
if not self.daemon:
|
|
with _shutdown_locks_lock:
|
|
_maintain_shutdown_locks()
|
|
_shutdown_locks.add(self._tstate_lock)
|
|
|
|
def _bootstrap_inner(self):
|
|
try:
|
|
self._set_ident()
|
|
self._set_tstate_lock()
|
|
if _HAVE_THREAD_NATIVE_ID:
|
|
self._set_native_id()
|
|
self._started.set()
|
|
with _active_limbo_lock:
|
|
_active[self._ident] = self
|
|
del _limbo[self]
|
|
|
|
if _trace_hook:
|
|
_sys.settrace(_trace_hook)
|
|
if _profile_hook:
|
|
_sys.setprofile(_profile_hook)
|
|
|
|
try:
|
|
self.run()
|
|
except:
|
|
self._invoke_excepthook(self)
|
|
finally:
|
|
self._delete()
|
|
|
|
def _stop(self):
|
|
# After calling ._stop(), .is_alive() returns False and .join() returns
|
|
# immediately. ._tstate_lock must be released before calling ._stop().
|
|
#
|
|
# Normal case: C code at the end of the thread's life
|
|
# (release_sentinel in _threadmodule.c) releases ._tstate_lock, and
|
|
# that's detected by our ._wait_for_tstate_lock(), called by .join()
|
|
# and .is_alive(). Any number of threads _may_ call ._stop()
|
|
# simultaneously (for example, if multiple threads are blocked in
|
|
# .join() calls), and they're not serialized. That's harmless -
|
|
# they'll just make redundant rebindings of ._is_stopped and
|
|
# ._tstate_lock. Obscure: we rebind ._tstate_lock last so that the
|
|
# "assert self._is_stopped" in ._wait_for_tstate_lock() always works
|
|
# (the assert is executed only if ._tstate_lock is None).
|
|
#
|
|
# Special case: _main_thread releases ._tstate_lock via this
|
|
# module's _shutdown() function.
|
|
lock = self._tstate_lock
|
|
if lock is not None:
|
|
assert not lock.locked()
|
|
self._is_stopped = True
|
|
self._tstate_lock = None
|
|
if not self.daemon:
|
|
with _shutdown_locks_lock:
|
|
# Remove our lock and other released locks from _shutdown_locks
|
|
_maintain_shutdown_locks()
|
|
|
|
def _delete(self):
|
|
"Remove current thread from the dict of currently running threads."
|
|
with _active_limbo_lock:
|
|
del _active[get_ident()]
|
|
# There must not be any python code between the previous line
|
|
# and after the lock is released. Otherwise a tracing function
|
|
# could try to acquire the lock again in the same thread, (in
|
|
# current_thread()), and would block.
|
|
|
|
def join(self, timeout=None):
|
|
"""Wait until the thread terminates.
|
|
|
|
This blocks the calling thread until the thread whose join() method is
|
|
called terminates -- either normally or through an unhandled exception
|
|
or until the optional timeout occurs.
|
|
|
|
When the timeout argument is present and not None, it should be a
|
|
floating point number specifying a timeout for the operation in seconds
|
|
(or fractions thereof). As join() always returns None, you must call
|
|
is_alive() after join() to decide whether a timeout happened -- if the
|
|
thread is still alive, the join() call timed out.
|
|
|
|
When the timeout argument is not present or None, the operation will
|
|
block until the thread terminates.
|
|
|
|
A thread can be join()ed many times.
|
|
|
|
join() raises a RuntimeError if an attempt is made to join the current
|
|
thread as that would cause a deadlock. It is also an error to join() a
|
|
thread before it has been started and attempts to do so raises the same
|
|
exception.
|
|
|
|
"""
|
|
if not self._initialized:
|
|
raise RuntimeError("Thread.__init__() not called")
|
|
if not self._started.is_set():
|
|
raise RuntimeError("cannot join thread before it is started")
|
|
if self is current_thread():
|
|
raise RuntimeError("cannot join current thread")
|
|
|
|
if timeout is None:
|
|
self._wait_for_tstate_lock()
|
|
else:
|
|
# the behavior of a negative timeout isn't documented, but
|
|
# historically .join(timeout=x) for x<0 has acted as if timeout=0
|
|
self._wait_for_tstate_lock(timeout=max(timeout, 0))
|
|
|
|
def _wait_for_tstate_lock(self, block=True, timeout=-1):
|
|
# Issue #18808: wait for the thread state to be gone.
|
|
# At the end of the thread's life, after all knowledge of the thread
|
|
# is removed from C data structures, C code releases our _tstate_lock.
|
|
# This method passes its arguments to _tstate_lock.acquire().
|
|
# If the lock is acquired, the C code is done, and self._stop() is
|
|
# called. That sets ._is_stopped to True, and ._tstate_lock to None.
|
|
lock = self._tstate_lock
|
|
if lock is None:
|
|
# already determined that the C code is done
|
|
assert self._is_stopped
|
|
return
|
|
|
|
try:
|
|
if lock.acquire(block, timeout):
|
|
lock.release()
|
|
self._stop()
|
|
except:
|
|
if lock.locked():
|
|
# bpo-45274: lock.acquire() acquired the lock, but the function
|
|
# was interrupted with an exception before reaching the
|
|
# lock.release(). It can happen if a signal handler raises an
|
|
# exception, like CTRL+C which raises KeyboardInterrupt.
|
|
lock.release()
|
|
self._stop()
|
|
raise
|
|
|
|
@property
|
|
def name(self):
|
|
"""A string used for identification purposes only.
|
|
|
|
It has no semantics. Multiple threads may be given the same name. The
|
|
initial name is set by the constructor.
|
|
|
|
"""
|
|
assert self._initialized, "Thread.__init__() not called"
|
|
return self._name
|
|
|
|
@name.setter
|
|
def name(self, name):
|
|
assert self._initialized, "Thread.__init__() not called"
|
|
self._name = str(name)
|
|
|
|
@property
|
|
def ident(self):
|
|
"""Thread identifier of this thread or None if it has not been started.
|
|
|
|
This is a nonzero integer. See the get_ident() function. Thread
|
|
identifiers may be recycled when a thread exits and another thread is
|
|
created. The identifier is available even after the thread has exited.
|
|
|
|
"""
|
|
assert self._initialized, "Thread.__init__() not called"
|
|
return self._ident
|
|
|
|
if _HAVE_THREAD_NATIVE_ID:
|
|
@property
|
|
def native_id(self):
|
|
"""Native integral thread ID of this thread, or None if it has not been started.
|
|
|
|
This is a non-negative integer. See the get_native_id() function.
|
|
This represents the Thread ID as reported by the kernel.
|
|
|
|
"""
|
|
assert self._initialized, "Thread.__init__() not called"
|
|
return self._native_id
|
|
|
|
def is_alive(self):
|
|
"""Return whether the thread is alive.
|
|
|
|
This method returns True just before the run() method starts until just
|
|
after the run() method terminates. See also the module function
|
|
enumerate().
|
|
|
|
"""
|
|
assert self._initialized, "Thread.__init__() not called"
|
|
if self._is_stopped or not self._started.is_set():
|
|
return False
|
|
self._wait_for_tstate_lock(False)
|
|
return not self._is_stopped
|
|
|
|
@property
|
|
def daemon(self):
|
|
"""A boolean value indicating whether this thread is a daemon thread.
|
|
|
|
This must be set before start() is called, otherwise RuntimeError is
|
|
raised. Its initial value is inherited from the creating thread; the
|
|
main thread is not a daemon thread and therefore all threads created in
|
|
the main thread default to daemon = False.
|
|
|
|
The entire Python program exits when only daemon threads are left.
|
|
|
|
"""
|
|
assert self._initialized, "Thread.__init__() not called"
|
|
return self._daemonic
|
|
|
|
@daemon.setter
|
|
def daemon(self, daemonic):
|
|
if not self._initialized:
|
|
raise RuntimeError("Thread.__init__() not called")
|
|
if daemonic and not _daemon_threads_allowed():
|
|
raise RuntimeError('daemon threads are disabled in this interpreter')
|
|
if self._started.is_set():
|
|
raise RuntimeError("cannot set daemon status of active thread")
|
|
self._daemonic = daemonic
|
|
|
|
def isDaemon(self):
|
|
"""Return whether this thread is a daemon.
|
|
|
|
This method is deprecated, use the daemon attribute instead.
|
|
|
|
"""
|
|
import warnings
|
|
warnings.warn('isDaemon() is deprecated, get the daemon attribute instead',
|
|
DeprecationWarning, stacklevel=2)
|
|
return self.daemon
|
|
|
|
def setDaemon(self, daemonic):
|
|
"""Set whether this thread is a daemon.
|
|
|
|
This method is deprecated, use the .daemon property instead.
|
|
|
|
"""
|
|
import warnings
|
|
warnings.warn('setDaemon() is deprecated, set the daemon attribute instead',
|
|
DeprecationWarning, stacklevel=2)
|
|
self.daemon = daemonic
|
|
|
|
def getName(self):
|
|
"""Return a string used for identification purposes only.
|
|
|
|
This method is deprecated, use the name attribute instead.
|
|
|
|
"""
|
|
import warnings
|
|
warnings.warn('getName() is deprecated, get the name attribute instead',
|
|
DeprecationWarning, stacklevel=2)
|
|
return self.name
|
|
|
|
def setName(self, name):
|
|
"""Set the name string for this thread.
|
|
|
|
This method is deprecated, use the name attribute instead.
|
|
|
|
"""
|
|
import warnings
|
|
warnings.warn('setName() is deprecated, set the name attribute instead',
|
|
DeprecationWarning, stacklevel=2)
|
|
self.name = name
|
|
|
|
|
|
try:
|
|
from _thread import (_excepthook as excepthook,
|
|
_ExceptHookArgs as ExceptHookArgs)
|
|
except ImportError:
|
|
# Simple Python implementation if _thread._excepthook() is not available
|
|
from traceback import print_exception as _print_exception
|
|
from collections import namedtuple
|
|
|
|
_ExceptHookArgs = namedtuple(
|
|
'ExceptHookArgs',
|
|
'exc_type exc_value exc_traceback thread')
|
|
|
|
def ExceptHookArgs(args):
|
|
return _ExceptHookArgs(*args)
|
|
|
|
def excepthook(args, /):
|
|
"""
|
|
Handle uncaught Thread.run() exception.
|
|
"""
|
|
if args.exc_type == SystemExit:
|
|
# silently ignore SystemExit
|
|
return
|
|
|
|
if _sys is not None and _sys.stderr is not None:
|
|
stderr = _sys.stderr
|
|
elif args.thread is not None:
|
|
stderr = args.thread._stderr
|
|
if stderr is None:
|
|
# do nothing if sys.stderr is None and sys.stderr was None
|
|
# when the thread was created
|
|
return
|
|
else:
|
|
# do nothing if sys.stderr is None and args.thread is None
|
|
return
|
|
|
|
if args.thread is not None:
|
|
name = args.thread.name
|
|
else:
|
|
name = get_ident()
|
|
print(f"Exception in thread {name}:",
|
|
file=stderr, flush=True)
|
|
_print_exception(args.exc_type, args.exc_value, args.exc_traceback,
|
|
file=stderr)
|
|
stderr.flush()
|
|
|
|
|
|
# Original value of threading.excepthook
|
|
__excepthook__ = excepthook
|
|
|
|
|
|
def _make_invoke_excepthook():
|
|
# Create a local namespace to ensure that variables remain alive
|
|
# when _invoke_excepthook() is called, even if it is called late during
|
|
# Python shutdown. It is mostly needed for daemon threads.
|
|
|
|
old_excepthook = excepthook
|
|
old_sys_excepthook = _sys.excepthook
|
|
if old_excepthook is None:
|
|
raise RuntimeError("threading.excepthook is None")
|
|
if old_sys_excepthook is None:
|
|
raise RuntimeError("sys.excepthook is None")
|
|
|
|
sys_exc_info = _sys.exc_info
|
|
local_print = print
|
|
local_sys = _sys
|
|
|
|
def invoke_excepthook(thread):
|
|
global excepthook
|
|
try:
|
|
hook = excepthook
|
|
if hook is None:
|
|
hook = old_excepthook
|
|
|
|
args = ExceptHookArgs([*sys_exc_info(), thread])
|
|
|
|
hook(args)
|
|
except Exception as exc:
|
|
exc.__suppress_context__ = True
|
|
del exc
|
|
|
|
if local_sys is not None and local_sys.stderr is not None:
|
|
stderr = local_sys.stderr
|
|
else:
|
|
stderr = thread._stderr
|
|
|
|
local_print("Exception in threading.excepthook:",
|
|
file=stderr, flush=True)
|
|
|
|
if local_sys is not None and local_sys.excepthook is not None:
|
|
sys_excepthook = local_sys.excepthook
|
|
else:
|
|
sys_excepthook = old_sys_excepthook
|
|
|
|
sys_excepthook(*sys_exc_info())
|
|
finally:
|
|
# Break reference cycle (exception stored in a variable)
|
|
args = None
|
|
|
|
return invoke_excepthook
|
|
|
|
|
|
# The timer class was contributed by Itamar Shtull-Trauring
|
|
|
|
class Timer(Thread):
|
|
"""Call a function after a specified number of seconds:
|
|
|
|
t = Timer(30.0, f, args=None, kwargs=None)
|
|
t.start()
|
|
t.cancel() # stop the timer's action if it's still waiting
|
|
|
|
"""
|
|
|
|
def __init__(self, interval, function, args=None, kwargs=None):
|
|
Thread.__init__(self)
|
|
self.interval = interval
|
|
self.function = function
|
|
self.args = args if args is not None else []
|
|
self.kwargs = kwargs if kwargs is not None else {}
|
|
self.finished = Event()
|
|
|
|
def cancel(self):
|
|
"""Stop the timer if it hasn't finished yet."""
|
|
self.finished.set()
|
|
|
|
def run(self):
|
|
self.finished.wait(self.interval)
|
|
if not self.finished.is_set():
|
|
self.function(*self.args, **self.kwargs)
|
|
self.finished.set()
|
|
|
|
|
|
# Special thread class to represent the main thread
|
|
|
|
class _MainThread(Thread):
|
|
|
|
def __init__(self):
|
|
Thread.__init__(self, name="MainThread", daemon=False)
|
|
self._set_tstate_lock()
|
|
self._started.set()
|
|
self._set_ident()
|
|
if _HAVE_THREAD_NATIVE_ID:
|
|
self._set_native_id()
|
|
with _active_limbo_lock:
|
|
_active[self._ident] = self
|
|
|
|
|
|
# Dummy thread class to represent threads not started here.
|
|
# These aren't garbage collected when they die, nor can they be waited for.
|
|
# If they invoke anything in threading.py that calls current_thread(), they
|
|
# leave an entry in the _active dict forever after.
|
|
# Their purpose is to return *something* from current_thread().
|
|
# They are marked as daemon threads so we won't wait for them
|
|
# when we exit (conform previous semantics).
|
|
|
|
class _DummyThread(Thread):
|
|
|
|
def __init__(self):
|
|
Thread.__init__(self, name=_newname("Dummy-%d"),
|
|
daemon=_daemon_threads_allowed())
|
|
|
|
self._started.set()
|
|
self._set_ident()
|
|
if _HAVE_THREAD_NATIVE_ID:
|
|
self._set_native_id()
|
|
with _active_limbo_lock:
|
|
_active[self._ident] = self
|
|
|
|
def _stop(self):
|
|
pass
|
|
|
|
def is_alive(self):
|
|
assert not self._is_stopped and self._started.is_set()
|
|
return True
|
|
|
|
def join(self, timeout=None):
|
|
assert False, "cannot join a dummy thread"
|
|
|
|
|
|
# Global API functions
|
|
|
|
def current_thread():
|
|
"""Return the current Thread object, corresponding to the caller's thread of control.
|
|
|
|
If the caller's thread of control was not created through the threading
|
|
module, a dummy thread object with limited functionality is returned.
|
|
|
|
"""
|
|
try:
|
|
return _active[get_ident()]
|
|
except KeyError:
|
|
return _DummyThread()
|
|
|
|
def currentThread():
|
|
"""Return the current Thread object, corresponding to the caller's thread of control.
|
|
|
|
This function is deprecated, use current_thread() instead.
|
|
|
|
"""
|
|
import warnings
|
|
warnings.warn('currentThread() is deprecated, use current_thread() instead',
|
|
DeprecationWarning, stacklevel=2)
|
|
return current_thread()
|
|
|
|
def active_count():
|
|
"""Return the number of Thread objects currently alive.
|
|
|
|
The returned count is equal to the length of the list returned by
|
|
enumerate().
|
|
|
|
"""
|
|
# NOTE: if the logic in here ever changes, update Modules/posixmodule.c
|
|
# warn_about_fork_with_threads() to match.
|
|
with _active_limbo_lock:
|
|
return len(_active) + len(_limbo)
|
|
|
|
def activeCount():
|
|
"""Return the number of Thread objects currently alive.
|
|
|
|
This function is deprecated, use active_count() instead.
|
|
|
|
"""
|
|
import warnings
|
|
warnings.warn('activeCount() is deprecated, use active_count() instead',
|
|
DeprecationWarning, stacklevel=2)
|
|
return active_count()
|
|
|
|
def _enumerate():
|
|
# Same as enumerate(), but without the lock. Internal use only.
|
|
return list(_active.values()) + list(_limbo.values())
|
|
|
|
def enumerate():
|
|
"""Return a list of all Thread objects currently alive.
|
|
|
|
The list includes daemonic threads, dummy thread objects created by
|
|
current_thread(), and the main thread. It excludes terminated threads and
|
|
threads that have not yet been started.
|
|
|
|
"""
|
|
with _active_limbo_lock:
|
|
return list(_active.values()) + list(_limbo.values())
|
|
|
|
|
|
_threading_atexits = []
|
|
_SHUTTING_DOWN = False
|
|
|
|
def _register_atexit(func, *arg, **kwargs):
|
|
"""CPython internal: register *func* to be called before joining threads.
|
|
|
|
The registered *func* is called with its arguments just before all
|
|
non-daemon threads are joined in `_shutdown()`. It provides a similar
|
|
purpose to `atexit.register()`, but its functions are called prior to
|
|
threading shutdown instead of interpreter shutdown.
|
|
|
|
For similarity to atexit, the registered functions are called in reverse.
|
|
"""
|
|
if _SHUTTING_DOWN:
|
|
raise RuntimeError("can't register atexit after shutdown")
|
|
|
|
call = functools.partial(func, *arg, **kwargs)
|
|
_threading_atexits.append(call)
|
|
|
|
|
|
from _thread import stack_size
|
|
|
|
# Create the main thread object,
|
|
# and make it available for the interpreter
|
|
# (Py_Main) as threading._shutdown.
|
|
|
|
_main_thread = _MainThread()
|
|
|
|
def _shutdown():
|
|
"""
|
|
Wait until the Python thread state of all non-daemon threads get deleted.
|
|
"""
|
|
# Obscure: other threads may be waiting to join _main_thread. That's
|
|
# dubious, but some code does it. We can't wait for C code to release
|
|
# the main thread's tstate_lock - that won't happen until the interpreter
|
|
# is nearly dead. So we release it here. Note that just calling _stop()
|
|
# isn't enough: other threads may already be waiting on _tstate_lock.
|
|
if _main_thread._is_stopped:
|
|
# _shutdown() was already called
|
|
return
|
|
|
|
global _SHUTTING_DOWN
|
|
_SHUTTING_DOWN = True
|
|
|
|
# Call registered threading atexit functions before threads are joined.
|
|
# Order is reversed, similar to atexit.
|
|
for atexit_call in reversed(_threading_atexits):
|
|
atexit_call()
|
|
|
|
# Main thread
|
|
if _main_thread.ident == get_ident():
|
|
tlock = _main_thread._tstate_lock
|
|
# The main thread isn't finished yet, so its thread state lock can't
|
|
# have been released.
|
|
assert tlock is not None
|
|
assert tlock.locked()
|
|
tlock.release()
|
|
_main_thread._stop()
|
|
else:
|
|
# bpo-1596321: _shutdown() must be called in the main thread.
|
|
# If the threading module was not imported by the main thread,
|
|
# _main_thread is the thread which imported the threading module.
|
|
# In this case, ignore _main_thread, similar behavior than for threads
|
|
# spawned by C libraries or using _thread.start_new_thread().
|
|
pass
|
|
|
|
# Join all non-deamon threads
|
|
while True:
|
|
with _shutdown_locks_lock:
|
|
locks = list(_shutdown_locks)
|
|
_shutdown_locks.clear()
|
|
|
|
if not locks:
|
|
break
|
|
|
|
for lock in locks:
|
|
# mimic Thread.join()
|
|
lock.acquire()
|
|
lock.release()
|
|
|
|
# new threads can be spawned while we were waiting for the other
|
|
# threads to complete
|
|
|
|
|
|
def main_thread():
|
|
"""Return the main thread object.
|
|
|
|
In normal conditions, the main thread is the thread from which the
|
|
Python interpreter was started.
|
|
"""
|
|
return _main_thread
|
|
|
|
# get thread-local implementation, either from the thread
|
|
# module, or from the python fallback
|
|
|
|
try:
|
|
from _thread import _local as local
|
|
except ImportError:
|
|
from _threading_local import local
|
|
|
|
|
|
def _after_fork():
|
|
"""
|
|
Cleanup threading module state that should not exist after a fork.
|
|
"""
|
|
# Reset _active_limbo_lock, in case we forked while the lock was held
|
|
# by another (non-forked) thread. http://bugs.python.org/issue874900
|
|
global _active_limbo_lock, _main_thread
|
|
global _shutdown_locks_lock, _shutdown_locks
|
|
_active_limbo_lock = RLock()
|
|
|
|
# fork() only copied the current thread; clear references to others.
|
|
new_active = {}
|
|
|
|
try:
|
|
current = _active[get_ident()]
|
|
except KeyError:
|
|
# fork() was called in a thread which was not spawned
|
|
# by threading.Thread. For example, a thread spawned
|
|
# by thread.start_new_thread().
|
|
current = _MainThread()
|
|
|
|
_main_thread = current
|
|
|
|
# reset _shutdown() locks: threads re-register their _tstate_lock below
|
|
_shutdown_locks_lock = _allocate_lock()
|
|
_shutdown_locks = set()
|
|
|
|
with _active_limbo_lock:
|
|
# Dangling thread instances must still have their locks reset,
|
|
# because someone may join() them.
|
|
threads = set(_enumerate())
|
|
threads.update(_dangling)
|
|
for thread in threads:
|
|
# Any lock/condition variable may be currently locked or in an
|
|
# invalid state, so we reinitialize them.
|
|
if thread is current:
|
|
# There is only one active thread. We reset the ident to
|
|
# its new value since it can have changed.
|
|
thread._reset_internal_locks(True)
|
|
ident = get_ident()
|
|
thread._ident = ident
|
|
new_active[ident] = thread
|
|
else:
|
|
# All the others are already stopped.
|
|
thread._reset_internal_locks(False)
|
|
thread._stop()
|
|
|
|
_limbo.clear()
|
|
_active.clear()
|
|
_active.update(new_active)
|
|
assert len(_active) == 1
|
|
|
|
|
|
if hasattr(_os, "register_at_fork"):
|
|
_os.register_at_fork(after_in_child=_after_fork)
|