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Issue #18757: Improved cross-references in the concurrent package.
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@ -40,7 +40,7 @@ Executor Objects
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.. method:: map(func, *iterables, timeout=None)
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Equivalent to ``map(func, *iterables)`` except *func* is executed
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Equivalent to :func:`map(func, *iterables) <map>` except *func* is executed
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asynchronously and several calls to *func* may be made concurrently. The
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returned iterator raises a :exc:`TimeoutError` if
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:meth:`~iterator.__next__` is called and the result isn't available
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@ -386,7 +386,7 @@ The :mod:`multiprocessing` package mostly replicates the API of the
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Unix daemons or services, they are normal processes that will be
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terminated (and not joined) if non-daemonic processes have exited.
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In addition to the :class:`Threading.Thread` API, :class:`Process` objects
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In addition to the :class:`threading.Thread` API, :class:`Process` objects
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also support the following attributes and methods:
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.. attribute:: pid
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@ -405,7 +405,7 @@ The :mod:`multiprocessing` package mostly replicates the API of the
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The process's authentication key (a byte string).
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When :mod:`multiprocessing` is initialized the main process is assigned a
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random string using :func:`os.random`.
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random string using :func:`os.urandom`.
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When a :class:`Process` object is created, it will inherit the
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authentication key of its parent process, although this may be changed by
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@ -530,7 +530,7 @@ Note that one can also create a shared queue by using a manager object -- see
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(1) After putting an object on an empty queue there may be an
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infinitesimal delay before the queue's :meth:`~Queue.empty`
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method returns :const:`False` and :meth:`~Queue.get_nowait` can
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return without raising :exc:`Queue.Empty`.
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return without raising :exc:`queue.Empty`.
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(2) If multiple processes are enqueuing objects, it is possible for
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the objects to be received at the other end out-of-order.
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@ -547,7 +547,8 @@ Note that one can also create a shared queue by using a manager object -- see
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.. warning::
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As mentioned above, if a child process has put items on a queue (and it has
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not used :meth:`JoinableQueue.cancel_join_thread`), then that process will
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not used :meth:`JoinableQueue.cancel_join_thread
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<multiprocessing.Queue.cancel_join_thread>`), then that process will
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not terminate until all buffered items have been flushed to the pipe.
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This means that if you try joining that process you may get a deadlock unless
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@ -580,7 +581,7 @@ For an example of the usage of queues for interprocess communication see
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thread is started which transfers objects from a buffer into the pipe.
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The usual :exc:`queue.Empty` and :exc:`queue.Full` exceptions from the
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standard library's :mod:`Queue` module are raised to signal timeouts.
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standard library's :mod:`queue` module are raised to signal timeouts.
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:class:`Queue` implements all the methods of :class:`queue.Queue` except for
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:meth:`~queue.Queue.task_done` and :meth:`~queue.Queue.join`.
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@ -696,7 +697,7 @@ For an example of the usage of queues for interprocess communication see
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call to :meth:`task_done` tells the queue that the processing on the task
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is complete.
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If a :meth:`~Queue.join` is currently blocking, it will resume when all
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If a :meth:`~queue.Queue.join` is currently blocking, it will resume when all
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items have been processed (meaning that a :meth:`task_done` call was
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received for every item that had been :meth:`~Queue.put` into the queue).
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@ -712,7 +713,7 @@ For an example of the usage of queues for interprocess communication see
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queue. The count goes down whenever a consumer calls
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:meth:`task_done` to indicate that the item was retrieved and all work on
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it is complete. When the count of unfinished tasks drops to zero,
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:meth:`~Queue.join` unblocks.
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:meth:`~queue.Queue.join` unblocks.
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Miscellaneous
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@ -874,8 +875,8 @@ Connection objects are usually created using :func:`Pipe` -- see also
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.. versionadded:: 3.3
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Connection objects now support the context manager protocol -- see
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:ref:`typecontextmanager`. :meth:`__enter__` returns the
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connection object, and :meth:`__exit__` calls :meth:`close`.
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:ref:`typecontextmanager`. :meth:`~contextmanager.__enter__` returns the
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connection object, and :meth:`~contextmanager.__exit__` calls :meth:`close`.
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For example:
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@ -948,7 +949,7 @@ object -- see :ref:`multiprocessing-managers`.
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object from :mod:`multiprocessing`.
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.. versionchanged:: 3.3
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The :meth:`wait_for` method was added.
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The :meth:`~threading.Condition.wait_for` method was added.
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.. class:: Event()
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@ -1095,8 +1096,9 @@ processes.
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array.
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If *lock* is ``True`` (the default) then a new lock object is created to
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synchronize access to the value. If *lock* is a :class:`Lock` or
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:class:`RLock` object then that will be used to synchronize access to the
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synchronize access to the value. If *lock* is a
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:class:`~multiprocessing.Lock` or :class:`~multiprocessing.RLock` object
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then that will be used to synchronize access to the
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value. If *lock* is ``False`` then access to the returned object will not be
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automatically protected by a lock, so it will not necessarily be
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"process-safe".
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@ -1110,8 +1112,8 @@ processes.
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object.
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If *lock* is ``True`` (the default) then a new lock object is created to
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synchronize access to the value. If *lock* is a :class:`Lock` or
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:class:`RLock` object then that will be used to synchronize access to the
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synchronize access to the value. If *lock* is a :class:`~multiprocessing.Lock` or
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:class:`~multiprocessing.RLock` object then that will be used to synchronize access to the
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value. If *lock* is ``False`` then access to the returned object will not be
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automatically protected by a lock, so it will not necessarily be
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"process-safe".
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@ -1296,8 +1298,8 @@ their parent process exits. The manager classes are defined in the
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:attr:`proxytype._exposed_` is used instead if it exists.) In the case
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where no exposed list is specified, all "public methods" of the shared
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object will be accessible. (Here a "public method" means any attribute
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which has a :meth:`__call__` method and whose name does not begin with
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``'_'``.)
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which has a :meth:`~object.__call__` method and whose name does not begin
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with ``'_'``.)
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*method_to_typeid* is a mapping used to specify the return type of those
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exposed methods which should return a proxy. It maps method names to
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@ -1318,11 +1320,11 @@ their parent process exits. The manager classes are defined in the
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.. versionchanged:: 3.3
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Manager objects support the context manager protocol -- see
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:ref:`typecontextmanager`. :meth:`__enter__` starts the server
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process (if it has not already started) and then returns the
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manager object. :meth:`__exit__` calls :meth:`shutdown`.
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:ref:`typecontextmanager`. :meth:`~contextmanager.__enter__` starts the
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server process (if it has not already started) and then returns the
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manager object. :meth:`~contextmanager.__exit__` calls :meth:`shutdown`.
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In previous versions :meth:`__enter__` did not start the
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In previous versions :meth:`~contextmanager.__enter__` did not start the
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manager's server process if it was not already started.
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.. class:: SyncManager
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@ -1354,7 +1356,7 @@ their parent process exits. The manager classes are defined in the
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:class:`threading.Lock` or :class:`threading.RLock` object.
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.. versionchanged:: 3.3
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The :meth:`wait_for` method was added.
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The :meth:`~threading.Condition.wait_for` method was added.
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.. method:: Event()
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@ -1798,8 +1800,8 @@ with the :class:`Pool` class.
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.. versionadded:: 3.3
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Pool objects now support the context manager protocol -- see
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:ref:`typecontextmanager`. :meth:`__enter__` returns the pool
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object, and :meth:`__exit__` calls :meth:`terminate`.
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:ref:`typecontextmanager`. :meth:`~contextmanager.__enter__` returns the
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pool object, and :meth:~contextmanager.`__exit__` calls :meth:`terminate`.
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.. class:: AsyncResult
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@ -1860,7 +1862,8 @@ Listeners and Clients
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:synopsis: API for dealing with sockets.
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Usually message passing between processes is done using queues or by using
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:class:`Connection` objects returned by :func:`Pipe`.
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:class:`~multiprocessing.Connection` objects returned by
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:func:`~multiprocessing.Pipe`.
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However, the :mod:`multiprocessing.connection` module allows some extra
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flexibility. It basically gives a high level message oriented API for dealing
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@ -1928,7 +1931,8 @@ multiple connections at the same time.
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private temporary directory created using :func:`tempfile.mkstemp`.
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If the listener object uses a socket then *backlog* (1 by default) is passed
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to the :meth:`listen` method of the socket once it has been bound.
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to the :meth:`~socket.socket.listen` method of the socket once it has been
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bound.
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If *authenticate* is ``True`` (``False`` by default) or *authkey* is not
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``None`` then digest authentication is used.
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@ -1946,8 +1950,8 @@ multiple connections at the same time.
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.. method:: accept()
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Accept a connection on the bound socket or named pipe of the listener
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object and return a :class:`Connection` object. If authentication is
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attempted and fails, then
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object and return a :class:`~multiprocessing.Connection` object. If
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authentication is attempted and fails, then
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:exc:`~multiprocessing.AuthenticationError` is raised.
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.. method:: close()
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@ -1969,8 +1973,8 @@ multiple connections at the same time.
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.. versionadded:: 3.3
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Listener objects now support the context manager protocol -- see
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:ref:`typecontextmanager`. :meth:`__enter__` returns the
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listener object, and :meth:`__exit__` calls :meth:`close`.
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:ref:`typecontextmanager`. :meth:`~contextmanager.__enter__` returns the
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listener object, and :meth:~contextmanager.`__exit__` calls :meth:`close`.
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.. function:: wait(object_list, timeout=None)
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@ -2106,7 +2110,8 @@ an ``'AF_PIPE'`` address rather than an ``'AF_UNIX'`` address.
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Authentication keys
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~~~~~~~~~~~~~~~~~~~
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When one uses :meth:`Connection.recv`, the data received is automatically
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When one uses :meth:`Connection.recv <multiprocessing.Connection.recv>`, the
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data received is automatically
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unpickled. Unfortunately unpickling data from an untrusted source is a security
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risk. Therefore :class:`Listener` and :func:`Client` use the :mod:`hmac` module
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to provide digest authentication.
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@ -2256,9 +2261,10 @@ Joining zombie processes
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On Unix when a process finishes but has not been joined it becomes a zombie.
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There should never be very many because each time a new process starts (or
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:func:`active_children` is called) all completed processes which have not
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yet been joined will be joined. Also calling a finished process's
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:meth:`Process.is_alive` will join the process. Even so it is probably good
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:func:`~multiprocessing.active_children` is called) all completed processes
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which have not yet been joined will be joined. Also calling a finished
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process's :meth:`Process.is_alive <multiprocessing.Process.is_alive>` will
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join the process. Even so it is probably good
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practice to explicitly join all the processes that you start.
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Better to inherit than pickle/unpickle
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@ -2271,20 +2277,23 @@ Better to inherit than pickle/unpickle
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Avoid terminating processes
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Using the :meth:`Process.terminate` method to stop a process is liable to
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Using the :meth:`Process.terminate <multiprocessing.Process.terminate>`
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method to stop a process is liable to
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cause any shared resources (such as locks, semaphores, pipes and queues)
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currently being used by the process to become broken or unavailable to other
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processes.
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Therefore it is probably best to only consider using
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:meth:`Process.terminate` on processes which never use any shared resources.
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:meth:`Process.terminate <multiprocessing.Process.terminate>` on processes
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which never use any shared resources.
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Joining processes that use queues
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Bear in mind that a process that has put items in a queue will wait before
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terminating until all the buffered items are fed by the "feeder" thread to
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the underlying pipe. (The child process can call the
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:meth:`Queue.cancel_join_thread` method of the queue to avoid this behaviour.)
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:meth:`Queue.cancel_join_thread <multiprocessing.Queue.cancel_join_thread>`
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method of the queue to avoid this behaviour.)
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This means that whenever you use a queue you need to make sure that all
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items which have been put on the queue will eventually be removed before the
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@ -2361,7 +2370,7 @@ Beware of replacing :data:`sys.stdin` with a "file like object"
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resulting in a bad file descriptor error, but introduces a potential danger
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to applications which replace :func:`sys.stdin` with a "file-like object"
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with output buffering. This danger is that if multiple processes call
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:func:`close()` on this file-like object, it could result in the same
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:meth:`~io.IOBase.close()` on this file-like object, it could result in the same
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data being flushed to the object multiple times, resulting in corruption.
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If you write a file-like object and implement your own caching, you can
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@ -2390,14 +2399,16 @@ More picklability
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as the ``target`` argument on Windows --- just define a function and use
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that instead.
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Also, if you subclass :class:`Process` then make sure that instances will be
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picklable when the :meth:`Process.start` method is called.
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Also, if you subclass :class:`~multiprocessing.Process` then make sure that
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instances will be picklable when the :meth:`Process.start
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<multiprocessing.Process.start>` method is called.
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Global variables
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Bear in mind that if code run in a child process tries to access a global
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variable, then the value it sees (if any) may not be the same as the value
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in the parent process at the time that :meth:`Process.start` was called.
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in the parent process at the time that :meth:`Process.start
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<multiprocessing.Process.start>` was called.
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However, global variables which are just module level constants cause no
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problems.
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@ -2453,7 +2464,7 @@ Demonstration of how to create and use customized managers and proxies:
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:language: python3
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Using :class:`Pool`:
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Using :class:`~multiprocessing.pool.Pool`:
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.. literalinclude:: ../includes/mp_pool.py
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:language: python3
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@ -54,13 +54,15 @@ The :mod:`queue` module defines the following classes and exceptions:
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.. exception:: Empty
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Exception raised when non-blocking :meth:`get` (or :meth:`get_nowait`) is called
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Exception raised when non-blocking :meth:`~Queue.get` (or
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:meth:`~Queue.get_nowait`) is called
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on a :class:`Queue` object which is empty.
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.. exception:: Full
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Exception raised when non-blocking :meth:`put` (or :meth:`put_nowait`) is called
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Exception raised when non-blocking :meth:`~Queue.put` (or
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:meth:`~Queue.put_nowait`) is called
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on a :class:`Queue` object which is full.
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@ -181,6 +183,6 @@ Example of how to wait for enqueued tasks to be completed::
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context.
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:class:`collections.deque` is an alternative implementation of unbounded
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queues with fast atomic :func:`append` and :func:`popleft` operations that
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do not require locking.
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queues with fast atomic :meth:`~collections.deque.append` and
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:meth:`~collections.deque.popleft` operations that do not require locking.
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@ -78,7 +78,7 @@ The module defines the following:
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This is a straightforward interface to the Unix :c:func:`select` system call.
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The first three arguments are sequences of 'waitable objects': either
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integers representing file descriptors or objects with a parameterless method
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named :meth:`fileno` returning such an integer:
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named :meth:`~io.IOBase.fileno` returning such an integer:
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* *rlist*: wait until ready for reading
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* *wlist*: wait until ready for writing
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@ -104,8 +104,8 @@ The module defines the following:
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objects <file object>` (e.g. ``sys.stdin``, or objects returned by
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:func:`open` or :func:`os.popen`), socket objects returned by
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:func:`socket.socket`. You may also define a :dfn:`wrapper` class yourself,
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as long as it has an appropriate :meth:`fileno` method (that really returns
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a file descriptor, not just a random integer).
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as long as it has an appropriate :meth:`~io.IOBase.fileno` method (that
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really returns a file descriptor, not just a random integer).
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.. note::
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@ -119,7 +119,7 @@ The module defines the following:
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.. attribute:: PIPE_BUF
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The minimum number of bytes which can be written without blocking to a pipe
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when the pipe has been reported as ready for writing by :func:`select`,
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when the pipe has been reported as ready for writing by :func:`~select.select`,
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:func:`poll` or another interface in this module. This doesn't apply
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to other kind of file-like objects such as sockets.
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@ -147,10 +147,10 @@ object.
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.. method:: devpoll.register(fd[, eventmask])
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Register a file descriptor with the polling object. Future calls to the
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:meth:`poll` method will then check whether the file descriptor has any pending
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I/O events. *fd* can be either an integer, or an object with a :meth:`fileno`
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method that returns an integer. File objects implement :meth:`fileno`, so they
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can also be used as the argument.
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:meth:`poll` method will then check whether the file descriptor has any
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pending I/O events. *fd* can be either an integer, or an object with a
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:meth:`~io.IOBase.fileno` method that returns an integer. File objects
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implement :meth:`!fileno`, so they can also be used as the argument.
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*eventmask* is an optional bitmask describing the type of events you want to
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check for. The constants are the same that with :c:func:`poll`
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@ -176,7 +176,7 @@ object.
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Remove a file descriptor being tracked by a polling object. Just like the
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:meth:`register` method, *fd* can be an integer or an object with a
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:meth:`fileno` method that returns an integer.
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:meth:`~io.IOBase.fileno` method that returns an integer.
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Attempting to remove a file descriptor that was never registered is
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safely ignored.
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@ -288,10 +288,10 @@ linearly scanned again. :c:func:`select` is O(highest file descriptor), while
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.. method:: poll.register(fd[, eventmask])
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Register a file descriptor with the polling object. Future calls to the
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:meth:`poll` method will then check whether the file descriptor has any pending
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I/O events. *fd* can be either an integer, or an object with a :meth:`fileno`
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method that returns an integer. File objects implement :meth:`fileno`, so they
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can also be used as the argument.
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:meth:`poll` method will then check whether the file descriptor has any
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pending I/O events. *fd* can be either an integer, or an object with a
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:meth:`~io.IOBase.fileno` method that returns an integer. File objects
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implement :meth:`!fileno`, so they can also be used as the argument.
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*eventmask* is an optional bitmask describing the type of events you want to
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check for, and can be a combination of the constants :const:`POLLIN`,
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@ -330,7 +330,7 @@ linearly scanned again. :c:func:`select` is O(highest file descriptor), while
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Remove a file descriptor being tracked by a polling object. Just like the
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:meth:`register` method, *fd* can be an integer or an object with a
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:meth:`fileno` method that returns an integer.
|
||||
:meth:`~io.IOBase.fileno` method that returns an integer.
|
||||
|
||||
Attempting to remove a file descriptor that was never registered causes a
|
||||
:exc:`KeyError` exception to be raised.
|
||||
@ -390,8 +390,8 @@ http://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2
|
||||
|
||||
Value used to identify the event. The interpretation depends on the filter
|
||||
but it's usually the file descriptor. In the constructor ident can either
|
||||
be an int or an object with a fileno() function. kevent stores the integer
|
||||
internally.
|
||||
be an int or an object with a :meth:`~io.IOBase.fileno` method. kevent
|
||||
stores the integer internally.
|
||||
|
||||
.. attribute:: kevent.filter
|
||||
|
||||
|
@ -76,7 +76,7 @@ use cases, the underlying :class:`Popen` interface can be used directly.
|
||||
Run command with arguments. Wait for command to complete. If the return
|
||||
code was zero then return, otherwise raise :exc:`CalledProcessError`. The
|
||||
:exc:`CalledProcessError` object will have the return code in the
|
||||
:attr:`returncode` attribute.
|
||||
:attr:`~CalledProcessError.returncode` attribute.
|
||||
|
||||
The arguments shown above are merely the most common ones, described below
|
||||
in :ref:`frequently-used-arguments` (hence the use of keyword-only notation
|
||||
@ -122,8 +122,8 @@ use cases, the underlying :class:`Popen` interface can be used directly.
|
||||
|
||||
If the return code was non-zero it raises a :exc:`CalledProcessError`. The
|
||||
:exc:`CalledProcessError` object will have the return code in the
|
||||
:attr:`returncode` attribute and any output in the :attr:`output`
|
||||
attribute.
|
||||
:attr:`~CalledProcessError.returncode` attribute and any output in the
|
||||
:attr:`~CalledProcessError.output` attribute.
|
||||
|
||||
The arguments shown above are merely the most common ones, described below
|
||||
in :ref:`frequently-used-arguments` (hence the use of keyword-only notation
|
||||
@ -607,14 +607,14 @@ Instances of the :class:`Popen` class have the following methods:
|
||||
|
||||
.. method:: Popen.poll()
|
||||
|
||||
Check if child process has terminated. Set and return :attr:`returncode`
|
||||
attribute.
|
||||
Check if child process has terminated. Set and return
|
||||
:attr:`~Popen.returncode` attribute.
|
||||
|
||||
|
||||
.. method:: Popen.wait(timeout=None)
|
||||
|
||||
Wait for child process to terminate. Set and return :attr:`returncode`
|
||||
attribute.
|
||||
Wait for child process to terminate. Set and return
|
||||
:attr:`~Popen.returncode` attribute.
|
||||
|
||||
If the process does not terminate after *timeout* seconds, raise a
|
||||
:exc:`TimeoutExpired` exception. It is safe to catch this exception and
|
||||
@ -860,8 +860,8 @@ In this section, "a becomes b" means that b can be used as a replacement for a.
|
||||
|
||||
In addition, the replacements using :func:`check_output` will fail with a
|
||||
:exc:`CalledProcessError` if the requested operation produces a non-zero
|
||||
return code. The output is still available as the ``output`` attribute of
|
||||
the raised exception.
|
||||
return code. The output is still available as the
|
||||
:attr:`~CalledProcessError.output` attribute of the raised exception.
|
||||
|
||||
In the following examples, we assume that the relevant functions have already
|
||||
been imported from the :mod:`subprocess` module.
|
||||
|
@ -63,7 +63,7 @@ This module defines the following functions:
|
||||
|
||||
Set a trace function for all threads started from the :mod:`threading` module.
|
||||
The *func* will be passed to :func:`sys.settrace` for each thread, before its
|
||||
:meth:`run` method is called.
|
||||
:meth:`~Thread.run` method is called.
|
||||
|
||||
|
||||
.. function:: setprofile(func)
|
||||
@ -72,7 +72,7 @@ This module defines the following functions:
|
||||
|
||||
Set a profile function for all threads started from the :mod:`threading` module.
|
||||
The *func* will be passed to :func:`sys.setprofile` for each thread, before its
|
||||
:meth:`run` method is called.
|
||||
:meth:`~Thread.run` method is called.
|
||||
|
||||
|
||||
.. function:: stack_size([size])
|
||||
@ -825,10 +825,11 @@ This class represents an action that should be run only after a certain amount
|
||||
of time has passed --- a timer. :class:`Timer` is a subclass of :class:`Thread`
|
||||
and as such also functions as an example of creating custom threads.
|
||||
|
||||
Timers are started, as with threads, by calling their :meth:`start` method. The
|
||||
timer can be stopped (before its action has begun) by calling the :meth:`cancel`
|
||||
method. The interval the timer will wait before executing its action may not be
|
||||
exactly the same as the interval specified by the user.
|
||||
Timers are started, as with threads, by calling their :meth:`~Timer.start`
|
||||
method. The timer can be stopped (before its action has begun) by calling the
|
||||
:meth:`~Timer.cancel` method. The interval the timer will wait before
|
||||
executing its action may not be exactly the same as the interval specified by
|
||||
the user.
|
||||
|
||||
For example::
|
||||
|
||||
|
Loading…
Reference in New Issue
Block a user