| """Thread module emulating a subset of Java's threading model.""" | |
| import os as _os | |
| import sys as _sys | |
| import _thread | |
| from time import monotonic as _time | |
| from traceback import format_exc as _format_exc | |
| from _weakrefset import WeakSet | |
| from itertools import islice as _islice, count as _count | |
| try: | |
| from _collections import deque as _deque | |
| except ImportError: | |
| from collections import deque as _deque | |
| # Note regarding PEP 8 compliant names | |
| # This threading model was originally inspired by Java, and inherited | |
| # the convention of camelCase function and method names from that | |
| # language. Those original names are not in any imminent danger of | |
| # being deprecated (even for Py3k),so this module provides them as an | |
| # alias for the PEP 8 compliant names | |
| # Note that using the new PEP 8 compliant names facilitates substitution | |
| # with the multiprocessing module, which doesn't provide the old | |
| # Java inspired names. | |
| __all__ = ['get_ident', 'active_count', 'Condition', 'current_thread', | |
| 'enumerate', 'main_thread', 'TIMEOUT_MAX', | |
| 'Event', 'Lock', 'RLock', 'Semaphore', 'BoundedSemaphore', 'Thread', | |
| 'Barrier', 'BrokenBarrierError', 'Timer', 'ThreadError', | |
| 'setprofile', 'settrace', 'local', 'stack_size'] | |
| # Rename some stuff so "from threading import *" is safe | |
| _start_new_thread = _thread.start_new_thread | |
| _allocate_lock = _thread.allocate_lock | |
| _set_sentinel = _thread._set_sentinel | |
| get_ident = _thread.get_ident | |
| ThreadError = _thread.error | |
| try: | |
| _CRLock = _thread.RLock | |
| except AttributeError: | |
| _CRLock = None | |
| TIMEOUT_MAX = _thread.TIMEOUT_MAX | |
| del _thread | |
| # Support for profile and trace hooks | |
| _profile_hook = None | |
| _trace_hook = None | |
| def setprofile(func): | |
| """Set a profile function for all threads started from the threading module. | |
| The func will be passed to sys.setprofile() for each thread, before its | |
| run() method is called. | |
| """ | |
| global _profile_hook | |
| _profile_hook = func | |
| def settrace(func): | |
| """Set a trace function for all threads started from the threading module. | |
| The func will be passed to sys.settrace() for each thread, before its run() | |
| method is called. | |
| """ | |
| global _trace_hook | |
| _trace_hook = func | |
| # Synchronization classes | |
| Lock = _allocate_lock | |
| def RLock(*args, **kwargs): | |
| """Factory function that returns a new reentrant lock. | |
| A reentrant lock must be released by the thread that acquired it. Once a | |
| thread has acquired a reentrant lock, the same thread may acquire it again | |
| without blocking; the thread must release it once for each time it has | |
| acquired it. | |
| """ | |
| if _CRLock is None: | |
| return _PyRLock(*args, **kwargs) | |
| return _CRLock(*args, **kwargs) | |
| class _RLock: | |
| """This class implements reentrant lock objects. | |
| A reentrant lock must be released by the thread that acquired it. Once a | |
| thread has acquired a reentrant lock, the same thread may acquire it | |
| again without blocking; the thread must release it once for each time it | |
| has acquired it. | |
| """ | |
| def __init__(self): | |
| self._block = _allocate_lock() | |
| self._owner = None | |
| self._count = 0 | |
| def __repr__(self): | |
| owner = self._owner | |
| try: | |
| owner = _active[owner].name | |
| except KeyError: | |
| pass | |
| return "<%s %s.%s object owner=%r count=%d at %s>" % ( | |
| "locked" if self._block.locked() else "unlocked", | |
| self.__class__.__module__, | |
| self.__class__.__qualname__, | |
| owner, | |
| self._count, | |
| hex(id(self)) | |
| ) | |
| def acquire(self, blocking=True, timeout=-1): | |
| """Acquire a lock, blocking or non-blocking. | |
| When invoked without arguments: if this thread already owns the lock, | |
| increment the recursion level by one, and return immediately. Otherwise, | |
| if another thread owns the lock, block until the lock is unlocked. Once | |
| the lock is unlocked (not owned by any thread), then grab ownership, set | |
| the recursion level to one, and return. If more than one thread is | |
| blocked waiting until the lock is unlocked, only one at a time will be | |
| able to grab ownership of the lock. There is no return value in this | |
| case. | |
| When invoked with the blocking argument set to true, do the same thing | |
| as when called without arguments, and return true. | |
| When invoked with the blocking argument set to false, do not block. If a | |
| call without an argument would block, return false immediately; | |
| otherwise, do the same thing as when called without arguments, and | |
| return true. | |
| When invoked with the floating-point timeout argument set to a positive | |
| value, block for at most the number of seconds specified by timeout | |
| and as long as the lock cannot be acquired. Return true if the lock has | |
| been acquired, false if the timeout has elapsed. | |
| """ | |
| me = get_ident() | |
| if self._owner == me: | |
| self._count += 1 | |
| return 1 | |
| rc = self._block.acquire(blocking, timeout) | |
| if rc: | |
| self._owner = me | |
| self._count = 1 | |
| return rc | |
| __enter__ = acquire | |
| def release(self): | |
| """Release a lock, decrementing the recursion level. | |
| If after the decrement it is zero, reset the lock to unlocked (not owned | |
| by any thread), and if any other threads are blocked waiting for the | |
| lock to become unlocked, allow exactly one of them to proceed. If after | |
| the decrement the recursion level is still nonzero, the lock remains | |
| locked and owned by the calling thread. | |
| Only call this method when the calling thread owns the lock. A | |
| RuntimeError is raised if this method is called when the lock is | |
| unlocked. | |
| There is no return value. | |
| """ | |
| if self._owner != get_ident(): | |
| raise RuntimeError("cannot release un-acquired lock") | |
| self._count = count = self._count - 1 | |
| if not count: | |
| self._owner = None | |
| self._block.release() | |
| def __exit__(self, t, v, tb): | |
| self.release() | |
| # Internal methods used by condition variables | |
| def _acquire_restore(self, state): | |
| self._block.acquire() | |
| self._count, self._owner = state | |
| def _release_save(self): | |
| if self._count == 0: | |
| raise RuntimeError("cannot release un-acquired lock") | |
| count = self._count | |
| self._count = 0 | |
| owner = self._owner | |
| self._owner = None | |
| self._block.release() | |
| return (count, owner) | |
| def _is_owned(self): | |
| return self._owner == get_ident() | |
| _PyRLock = _RLock | |
| class Condition: | |
| """Class that implements a condition variable. | |
| A condition variable allows one or more threads to wait until they are | |
| notified by another thread. | |
| If the lock argument is given and not None, it must be a Lock or RLock | |
| object, and it is used as the underlying lock. Otherwise, a new RLock object | |
| is created and used as the underlying lock. | |
| """ | |
| def __init__(self, lock=None): | |
| if lock is None: | |
| lock = RLock() | |
| self._lock = lock | |
| # Export the lock's acquire() and release() methods | |
| self.acquire = lock.acquire | |
| self.release = lock.release | |
| # If the lock defines _release_save() and/or _acquire_restore(), | |
| # these override the default implementations (which just call | |
| # release() and acquire() on the lock). Ditto for _is_owned(). | |
| try: | |
| self._release_save = lock._release_save | |
| except AttributeError: | |
| pass | |
| try: | |
| self._acquire_restore = lock._acquire_restore | |
| except AttributeError: | |
| pass | |
| try: | |
| self._is_owned = lock._is_owned | |
| except AttributeError: | |
| pass | |
| self._waiters = _deque() | |
| def __enter__(self): | |
| return self._lock.__enter__() | |
| def __exit__(self, *args): | |
| return self._lock.__exit__(*args) | |
| def __repr__(self): | |
| return "<Condition(%s, %d)>" % (self._lock, len(self._waiters)) | |
| def _release_save(self): | |
| self._lock.release() # No state to save | |
| def _acquire_restore(self, x): | |
| self._lock.acquire() # Ignore saved state | |
| def _is_owned(self): | |
| # Return True if lock is owned by current_thread. | |
| # This method is called only if _lock doesn't have _is_owned(). | |
| if self._lock.acquire(0): | |
| self._lock.release() | |
| return False | |
| else: | |
| return True | |
| def wait(self, timeout=None): | |
| """Wait until notified or until a timeout occurs. | |
| If the calling thread has not acquired the lock when this method is | |
| called, a RuntimeError is raised. | |
| This method releases the underlying lock, and then blocks until it is | |
| awakened by a notify() or notify_all() call for the same condition | |
| variable in another thread, or until the optional timeout occurs. Once | |
| awakened or timed out, it re-acquires the lock and returns. | |
| 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). | |
| When the underlying lock is an RLock, it is not released using its | |
| release() method, since this may not actually unlock the lock when it | |
| was acquired multiple times recursively. Instead, an internal interface | |
| of the RLock class is used, which really unlocks it even when it has | |
| been recursively acquired several times. Another internal interface is | |
| then used to restore the recursion level when the lock is reacquired. | |
| """ | |
| if not self._is_owned(): | |
| raise RuntimeError("cannot wait on un-acquired lock") | |
| waiter = _allocate_lock() | |
| waiter.acquire() | |
| self._waiters.append(waiter) | |
| saved_state = self._release_save() | |
| gotit = False | |
| try: # restore state no matter what (e.g., KeyboardInterrupt) | |
| if timeout is None: | |
| waiter.acquire() | |
| gotit = True | |
| else: | |
| if timeout > 0: | |
| gotit = waiter.acquire(True, timeout) | |
| else: | |
| gotit = waiter.acquire(False) | |
| return gotit | |
| finally: | |
| self._acquire_restore(saved_state) | |
| if not gotit: | |
| try: | |
| self._waiters.remove(waiter) | |
| except ValueError: | |
| pass | |
| def wait_for(self, predicate, timeout=None): | |
| """Wait until a condition evaluates to True. | |
| predicate should be a callable which result will be interpreted as a | |
| boolean value. A timeout may be provided giving the maximum time to | |
| wait. | |
| """ | |
| endtime = None | |
| waittime = timeout | |
| result = predicate() | |
| while not result: | |
| if waittime is not None: | |
| if endtime is None: | |
| endtime = _time() + waittime | |
| else: | |
| waittime = endtime - _time() | |
| if waittime <= 0: | |
| break | |
| self.wait(waittime) | |
| result = predicate() | |
| return result | |
| def notify(self, n=1): | |
| """Wake up one or more threads waiting on this condition, if any. | |
| If the calling thread has not acquired the lock when this method is | |
| called, a RuntimeError is raised. | |
| This method wakes up at most n of the threads waiting for the condition | |
| variable; it is a no-op if no threads are waiting. | |
| """ | |
| if not self._is_owned(): | |
| raise RuntimeError("cannot notify on un-acquired lock") | |
| all_waiters = self._waiters | |
| waiters_to_notify = _deque(_islice(all_waiters, n)) | |
| if not waiters_to_notify: | |
| return | |
| for waiter in waiters_to_notify: | |
| waiter.release() | |
| try: | |
| all_waiters.remove(waiter) | |
| except ValueError: | |
| pass | |
| def notify_all(self): | |
| """Wake up all threads waiting on this condition. | |
| If the calling thread has not acquired the lock when this method | |
| is called, a RuntimeError is raised. | |
| """ | |
| self.notify(len(self._waiters)) | |
| notifyAll = notify_all | |
| class Semaphore: | |
| """This class implements semaphore objects. | |
| Semaphores manage a counter representing the number of release() calls minus | |
| the number of acquire() calls, plus an initial value. The acquire() method | |
| blocks if necessary until it can return without making the counter | |
| negative. If not given, value defaults to 1. | |
| """ | |
| # After Tim Peters' semaphore class, but not quite the same (no maximum) | |
| def __init__(self, value=1): | |
| if value < 0: | |
| raise ValueError("semaphore initial value must be >= 0") | |
| self._cond = Condition(Lock()) | |
| self._value = value | |
| def acquire(self, blocking=True, timeout=None): | |
| """Acquire a semaphore, decrementing the internal counter by one. | |
| When invoked without arguments: if the internal counter is larger than | |
| zero on entry, decrement it by one and return immediately. If it is zero | |
| on entry, block, waiting until some other thread has called release() to | |
| make it larger than zero. This is done with proper interlocking so that | |
| if multiple acquire() calls are blocked, release() will wake exactly one | |
| of them up. The implementation may pick one at random, so the order in | |
| which blocked threads are awakened should not be relied on. There is no | |
| return value in this case. | |
| When invoked with blocking set to true, do the same thing as when called | |
| without arguments, and return true. | |
| When invoked with blocking set to false, do not block. If a call without | |
| an argument would block, return false immediately; otherwise, do the | |
| same thing as when called without arguments, and return true. | |
| When invoked with a timeout other than None, it will block for at | |
| most timeout seconds. If acquire does not complete successfully in | |
| that interval, return false. Return true otherwise. | |
| """ | |
| if not blocking and timeout is not None: | |
| raise ValueError("can't specify timeout for non-blocking acquire") | |
| rc = False | |
| endtime = None | |
| with self._cond: | |
| while self._value == 0: | |
| if not blocking: | |
| break | |
| if timeout is not None: | |
| if endtime is None: | |
| endtime = _time() + timeout | |
| else: | |
| timeout = endtime - _time() | |
| if timeout <= 0: | |
| break | |
| self._cond.wait(timeout) | |
| else: | |
| self._value -= 1 | |
| rc = True | |
| return rc | |
| __enter__ = acquire | |
| def release(self): | |
| """Release a semaphore, incrementing the internal counter by one. | |
| When the counter is zero on entry and another thread is waiting for it | |
| to become larger than zero again, wake up that thread. | |
| """ | |
| with self._cond: | |
| self._value += 1 | |
| self._cond.notify() | |
| def __exit__(self, t, v, tb): | |
| self.release() | |
| class BoundedSemaphore(Semaphore): | |
| """Implements a bounded semaphore. | |
| A bounded semaphore checks to make sure its current value doesn't exceed its | |
| initial value. If it does, ValueError is raised. In most situations | |
| semaphores are used to guard resources with limited capacity. | |
| If the semaphore is released too many times it's a sign of a bug. If not | |
| given, value defaults to 1. | |
| Like regular semaphores, bounded semaphores manage a counter representing | |
| the number of release() calls minus the number of acquire() calls, plus an | |
| initial value. The acquire() method blocks if necessary until it can return | |
| without making the counter negative. If not given, value defaults to 1. | |
| """ | |
| def __init__(self, value=1): | |
| Semaphore.__init__(self, value) | |
| self._initial_value = value | |
| def release(self): | |
| """Release a semaphore, incrementing the internal counter by one. | |
| 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. | |
| """ | |
| with self._cond: | |
| if self._value >= self._initial_value: | |
| raise ValueError("Semaphore released too many times") | |
| self._value += 1 | |
| self._cond.notify() | |
| 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 _reset_internal_locks(self): | |
| # private! called by Thread._reset_internal_locks by _after_fork() | |
| self._cond.__init__(Lock()) | |
| def is_set(self): | |
| """Return true if and only if the internal flag is true.""" | |
| return self._flag | |
| isSet = 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 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().__next__ | |
| _counter() # Consume 0 so first non-main thread has id 1. | |
| def _newname(template="Thread-%d"): | |
| return template % _counter() | |
| # Active thread administration | |
| _active_limbo_lock = _allocate_lock() | |
| _active = {} # maps thread id to Thread object | |
| _limbo = {} | |
| _dangling = WeakSet() | |
| # 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 | |
| # Need to store a reference to sys.exc_info for printing | |
| # out exceptions when a thread tries to use a global var. during interp. | |
| # shutdown and thus raises an exception about trying to perform some | |
| # operation on/with a NoneType | |
| _exc_info = _sys.exc_info | |
| # Keep sys.exc_clear too to clear the exception just before | |
| # allowing .join() to return. | |
| #XXX __exc_clear = _sys.exc_clear | |
| 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 the argument tuple 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 = {} | |
| self._target = target | |
| self._name = str(name or _newname()) | |
| self._args = args | |
| self._kwargs = kwargs | |
| if daemon is not None: | |
| self._daemonic = daemon | |
| else: | |
| self._daemonic = current_thread().daemon | |
| self._ident = None | |
| self._tstate_lock = None | |
| self._started = Event() | |
| self._is_stopped = False | |
| self._initialized = True | |
| # sys.stderr is not stored in the class like | |
| # sys.exc_info since it can be changed between instances | |
| self._stderr = _sys.stderr | |
| # 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._reset_internal_locks() | |
| if is_alive: | |
| self._set_tstate_lock() | |
| 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: | |
| 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() | |
| 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() | |
| def _bootstrap_inner(self): | |
| try: | |
| self._set_ident() | |
| self._set_tstate_lock() | |
| 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 SystemExit: | |
| pass | |
| except: | |
| # If sys.stderr is no more (most likely from interpreter | |
| # shutdown) use self._stderr. Otherwise still use sys (as in | |
| # _sys) in case sys.stderr was redefined since the creation of | |
| # self. | |
| if _sys and _sys.stderr is not None: | |
| print("Exception in thread %s:\n%s" % | |
| (self.name, _format_exc()), file=_sys.stderr) | |
| elif self._stderr is not None: | |
| # Do the best job possible w/o a huge amt. of code to | |
| # approximate a traceback (code ideas from | |
| # Lib/traceback.py) | |
| exc_type, exc_value, exc_tb = self._exc_info() | |
| try: | |
| print(( | |
| "Exception in thread " + self.name + | |
| " (most likely raised during interpreter shutdown):"), file=self._stderr) | |
| print(( | |
| "Traceback (most recent call last):"), file=self._stderr) | |
| while exc_tb: | |
| print(( | |
| ' File "%s", line %s, in %s' % | |
| (exc_tb.tb_frame.f_code.co_filename, | |
| exc_tb.tb_lineno, | |
| exc_tb.tb_frame.f_code.co_name)), file=self._stderr) | |
| exc_tb = exc_tb.tb_next | |
| print(("%s: %s" % (exc_type, exc_value)), file=self._stderr) | |
| self._stderr.flush() | |
| # Make sure that exc_tb gets deleted since it is a memory | |
| # hog; deleting everything else is just for thoroughness | |
| finally: | |
| del exc_type, exc_value, exc_tb | |
| finally: | |
| # Prevent a race in | |
| # test_threading.test_no_refcycle_through_target when | |
| # the exception keeps the target alive past when we | |
| # assert that it's dead. | |
| #XXX self._exc_clear() | |
| pass | |
| finally: | |
| with _active_limbo_lock: | |
| try: | |
| # We don't call self._delete() because it also | |
| # grabs _active_limbo_lock. | |
| del _active[get_ident()] | |
| except: | |
| pass | |
| 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 | |
| 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 | |
| elif lock.acquire(block, timeout): | |
| lock.release() | |
| self._stop() | |
| @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 | |
| 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. The module function enumerate() | |
| returns a list of all alive threads. | |
| """ | |
| 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 | |
| def isAlive(self): | |
| """Return whether the thread is alive. | |
| This method is deprecated, use is_alive() instead. | |
| """ | |
| import warnings | |
| warnings.warn('isAlive() is deprecated, use is_alive() instead', | |
| PendingDeprecationWarning, stacklevel=2) | |
| return self.is_alive() | |
| @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 no alive non-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 self._started.is_set(): | |
| raise RuntimeError("cannot set daemon status of active thread") | |
| self._daemonic = daemonic | |
| def isDaemon(self): | |
| return self.daemon | |
| def setDaemon(self, daemonic): | |
| self.daemon = daemonic | |
| def getName(self): | |
| return self.name | |
| def setName(self, name): | |
| self.name = name | |
| # 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() | |
| 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=True) | |
| self._started.set() | |
| self._set_ident() | |
| 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() | |
| currentThread = 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(). | |
| """ | |
| with _active_limbo_lock: | |
| return len(_active) + len(_limbo) | |
| activeCount = 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()) | |
| 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(): | |
| # 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 | |
| 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() | |
| t = _pickSomeNonDaemonThread() | |
| while t: | |
| t.join() | |
| t = _pickSomeNonDaemonThread() | |
| def _pickSomeNonDaemonThread(): | |
| for t in enumerate(): | |
| if not t.daemon and t.is_alive(): | |
| return t | |
| return None | |
| 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 | |
| _active_limbo_lock = _allocate_lock() | |
| # fork() only copied the current thread; clear references to others. | |
| new_active = {} | |
| current = current_thread() | |
| _main_thread = current | |
| 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) |