In [1]:
import threading
In [2]:
help(threading)
Help on module threading:
NAME
threading - Thread module emulating a subset of Java's threading model.
MODULE REFERENCE
https://docs.python.org/3.5/library/threading.html
The following documentation is automatically generated from the Python
source files. It may be incomplete, incorrect or include features that
are considered implementation detail and may vary between Python
implementations. When in doubt, consult the module reference at the
location listed above.
CLASSES
builtins.Exception(builtins.BaseException)
builtins.RuntimeError
builtins.object
_thread._local
Barrier
Condition
Event
Semaphore
BoundedSemaphore
Thread
Timer
class Barrier(builtins.object)
| Implements a Barrier.
|
| Useful for synchronizing a fixed number of threads at known synchronization
| points. Threads block on 'wait()' and are simultaneously once they have all
| made that call.
|
| Methods defined here:
|
| __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 uses as the
| default for all subsequent 'wait()' calls.
|
| 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.
|
| reset(self)
| Reset the barrier to the initial state.
|
| Any threads currently waiting will get the BrokenBarrier exception
| raised.
|
| 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'.
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| __dict__
| dictionary for instance variables (if defined)
|
| __weakref__
| list of weak references to the object (if defined)
|
| broken
| Return True if the barrier is in a broken state.
|
| n_waiting
| Return the number of threads currently waiting at the barrier.
|
| parties
| Return the number of threads required to trip the barrier.
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.
|
| Method resolution order:
| BoundedSemaphore
| Semaphore
| builtins.object
|
| Methods defined here:
|
| __init__(self, value=1)
| Initialize self. See help(type(self)) for accurate signature.
|
| 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.
|
| ----------------------------------------------------------------------
| Methods inherited from Semaphore:
|
| __enter__ = 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.
|
| __exit__(self, t, v, tb)
|
| 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.
|
| ----------------------------------------------------------------------
| Data descriptors inherited from Semaphore:
|
| __dict__
| dictionary for instance variables (if defined)
|
| __weakref__
| list of weak references to the object (if defined)
class Condition(builtins.object)
| 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.
|
| Methods defined here:
|
| __enter__(self)
|
| __exit__(self, *args)
|
| __init__(self, lock=None)
| Initialize self. See help(type(self)) for accurate signature.
|
| __repr__(self)
| Return repr(self).
|
| 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.
|
| notifyAll = notify_all(self)
|
| 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.
|
| 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.
|
| 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.
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| __dict__
| dictionary for instance variables (if defined)
|
| __weakref__
| list of weak references to the object (if defined)
class Event(builtins.object)
| 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.
|
| Methods defined here:
|
| __init__(self)
| Initialize self. See help(type(self)) for accurate signature.
|
| 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.
|
| isSet = is_set(self)
|
| is_set(self)
| Return true if and only if the internal flag is true.
|
| 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.
|
| 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.
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| __dict__
| dictionary for instance variables (if defined)
|
| __weakref__
| list of weak references to the object (if defined)
class Semaphore(builtins.object)
| 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.
|
| Methods defined here:
|
| __enter__ = acquire(self, blocking=True, timeout=None)
|
| __exit__(self, t, v, tb)
|
| __init__(self, value=1)
| Initialize self. See help(type(self)) for accurate signature.
|
| 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.
|
| 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.
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| __dict__
| dictionary for instance variables (if defined)
|
| __weakref__
| list of weak references to the object (if defined)
class Thread(builtins.object)
| 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.
|
| Methods defined here:
|
| __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.
|
| __repr__(self)
| Return repr(self).
|
| getName(self)
|
| isAlive = is_alive(self)
|
| isDaemon(self)
|
| 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.
|
| 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
| isAlive() 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.
|
| 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.
|
| setDaemon(self, daemonic)
|
| setName(self, name)
|
| 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.
|
| ----------------------------------------------------------------------
| Data descriptors defined here:
|
| __dict__
| dictionary for instance variables (if defined)
|
| __weakref__
| list of weak references to the object (if defined)
|
| daemon
| 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.
|
| ident
| Thread identifier of this thread or None if it has not been started.
|
| This is a nonzero integer. See the thread.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.
|
| name
| 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.
ThreadError = class RuntimeError(Exception)
| Unspecified run-time error.
|
| Method resolution order:
| RuntimeError
| Exception
| BaseException
| object
|
| Methods defined here:
|
| __init__(self, /, *args, **kwargs)
| Initialize self. See help(type(self)) for accurate signature.
|
| __new__(*args, **kwargs) from builtins.type
| Create and return a new object. See help(type) for accurate signature.
|
| ----------------------------------------------------------------------
| Methods inherited from BaseException:
|
| __delattr__(self, name, /)
| Implement delattr(self, name).
|
| __getattribute__(self, name, /)
| Return getattr(self, name).
|
| __reduce__(...)
| helper for pickle
|
| __repr__(self, /)
| Return repr(self).
|
| __setattr__(self, name, value, /)
| Implement setattr(self, name, value).
|
| __setstate__(...)
|
| __str__(self, /)
| Return str(self).
|
| with_traceback(...)
| Exception.with_traceback(tb) --
| set self.__traceback__ to tb and return self.
|
| ----------------------------------------------------------------------
| Data descriptors inherited from BaseException:
|
| __cause__
| exception cause
|
| __context__
| exception context
|
| __dict__
|
| __suppress_context__
|
| __traceback__
|
| args
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
|
| Method resolution order:
| Timer
| Thread
| builtins.object
|
| Methods defined here:
|
| __init__(self, interval, function, args=None, kwargs=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.
|
| cancel(self)
| Stop the timer if it hasn't finished yet.
|
| 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.
|
| ----------------------------------------------------------------------
| Methods inherited from Thread:
|
| __repr__(self)
| Return repr(self).
|
| getName(self)
|
| isAlive = 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.
|
| isDaemon(self)
|
| 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.
|
| 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
| isAlive() 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.
|
| setDaemon(self, daemonic)
|
| setName(self, name)
|
| 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.
|
| ----------------------------------------------------------------------
| Data descriptors inherited from Thread:
|
| __dict__
| dictionary for instance variables (if defined)
|
| __weakref__
| list of weak references to the object (if defined)
|
| daemon
| 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.
|
| ident
| Thread identifier of this thread or None if it has not been started.
|
| This is a nonzero integer. See the thread.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.
|
| name
| 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.
local = class _local(builtins.object)
| Thread-local data
|
| Methods defined here:
|
| __delattr__(self, name, /)
| Implement delattr(self, name).
|
| __getattribute__(self, name, /)
| Return getattr(self, name).
|
| __new__(*args, **kwargs) from builtins.type
| Create and return a new object. See help(type) for accurate signature.
|
| __setattr__(self, name, value, /)
| Implement setattr(self, name, value).
FUNCTIONS
Lock = allocate_lock(...)
allocate_lock() -> lock object
(allocate() is an obsolete synonym)
Create a new lock object. See help(type(threading.Lock())) for
information about locks.
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.
active_count()
Return the number of Thread objects currently alive.
The returned count is equal to the length of the list returned by
enumerate().
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.
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.
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.
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.
stack_size(...)
stack_size([size]) -> size
Return the thread stack size used when creating new threads. The
optional size argument specifies the stack size (in bytes) to be used
for subsequently created threads, and must be 0 (use platform or
configured default) or a positive integer value of at least 32,768 (32k).
If changing the thread stack size is unsupported, a ThreadError
exception is raised. If the specified size is invalid, a ValueError
exception is raised, and the stack size is unmodified. 32k bytes
currently the minimum supported stack size value to guarantee
sufficient stack space for the interpreter itself.
Note that some platforms may have particular restrictions on values for
the stack size, such as requiring a minimum stack size larger than 32kB or
requiring allocation in multiples of the system memory page size
- platform documentation should be referred to for more information
(4kB pages are common; using multiples of 4096 for the stack size is
the suggested approach in the absence of more specific information).
DATA
__all__ = ['active_count', 'Condition', 'current_thread', 'enumerate',...
FILE
/usr/lib/python3.5/threading.py
TO start a thread you need to call threading.Thread with 3 arguments target, name and the arguments to the function you are threading t = threading.Thread()
Blocking methods or blocking calls. Prevents doing other stuff until task is finished
t.join()
Content source: 211217613/python_meetup
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