diff options
Diffstat (limited to 'Doc/library')
| -rw-r--r-- | Doc/library/asyncio-dev.rst | 4 | ||||
| -rw-r--r-- | Doc/library/http.server.rst | 3 | ||||
| -rw-r--r-- | Doc/library/pathlib.rst | 7 | ||||
| -rw-r--r-- | Doc/library/platform.rst | 18 | ||||
| -rw-r--r-- | Doc/library/threading.rst | 114 |
5 files changed, 95 insertions, 51 deletions
diff --git a/Doc/library/asyncio-dev.rst b/Doc/library/asyncio-dev.rst index 44b507a9811..7831b613bd4 100644 --- a/Doc/library/asyncio-dev.rst +++ b/Doc/library/asyncio-dev.rst @@ -46,10 +46,6 @@ In addition to enabling the debug mode, consider also: When the debug mode is enabled: -* asyncio checks for :ref:`coroutines that were not awaited - <asyncio-coroutine-not-scheduled>` and logs them; this mitigates - the "forgotten await" pitfall. - * Many non-threadsafe asyncio APIs (such as :meth:`loop.call_soon` and :meth:`loop.call_at` methods) raise an exception if they are called from a wrong thread. diff --git a/Doc/library/http.server.rst b/Doc/library/http.server.rst index 54df4a7e804..02016c789b2 100644 --- a/Doc/library/http.server.rst +++ b/Doc/library/http.server.rst @@ -429,8 +429,7 @@ instantiation, of which this module provides three different variants: ``'Last-Modified:'`` header with the file's modification time. Then follows a blank line signifying the end of the headers, and then the - contents of the file are output. If the file's MIME type starts with - ``text/`` the file is opened in text mode; otherwise binary mode is used. + contents of the file are output. For example usage, see the implementation of the ``test`` function in :source:`Lib/http/server.py`. diff --git a/Doc/library/pathlib.rst b/Doc/library/pathlib.rst index 7d7692dea5c..86351e65dc4 100644 --- a/Doc/library/pathlib.rst +++ b/Doc/library/pathlib.rst @@ -1781,9 +1781,12 @@ The following wildcards are supported in patterns for ``?`` Matches one non-separator character. ``[seq]`` - Matches one character in *seq*. + Matches one character in *seq*, where *seq* is a sequence of characters. + Range expressions are supported; for example, ``[a-z]`` matches any lowercase ASCII letter. + Multiple ranges can be combined: ``[a-zA-Z0-9_]`` matches any ASCII letter, digit, or underscore. + ``[!seq]`` - Matches one character not in *seq*. + Matches one character not in *seq*, where *seq* follows the same rules as above. For a literal match, wrap the meta-characters in brackets. For example, ``"[?]"`` matches the character ``"?"``. diff --git a/Doc/library/platform.rst b/Doc/library/platform.rst index 5c999054323..06de152a742 100644 --- a/Doc/library/platform.rst +++ b/Doc/library/platform.rst @@ -188,24 +188,6 @@ Cross platform :attr:`processor` is resolved late instead of immediately. -Java platform -------------- - - -.. function:: java_ver(release='', vendor='', vminfo=('','',''), osinfo=('','','')) - - Version interface for Jython. - - Returns a tuple ``(release, vendor, vminfo, osinfo)`` with *vminfo* being a - tuple ``(vm_name, vm_release, vm_vendor)`` and *osinfo* being a tuple - ``(os_name, os_version, os_arch)``. Values which cannot be determined are set to - the defaults given as parameters (which all default to ``''``). - - .. deprecated-removed:: 3.13 3.15 - It was largely untested, had a confusing API, - and was only useful for Jython support. - - Windows platform ---------------- diff --git a/Doc/library/threading.rst b/Doc/library/threading.rst index 249c0a5cb03..7edcdcabdce 100644 --- a/Doc/library/threading.rst +++ b/Doc/library/threading.rst @@ -11,6 +11,52 @@ This module constructs higher-level threading interfaces on top of the lower level :mod:`_thread` module. +.. include:: ../includes/wasm-notavail.rst + +Introduction +------------ + +The :mod:`!threading` module provides a way to run multiple `threads +<https://en.wikipedia.org/wiki/Thread_(computing)>`_ (smaller +units of a process) concurrently within a single process. It allows for the +creation and management of threads, making it possible to execute tasks in +parallel, sharing memory space. Threads are particularly useful when tasks are +I/O bound, such as file operations or making network requests, +where much of the time is spent waiting for external resources. + +A typical use case for :mod:`!threading` includes managing a pool of worker +threads that can process multiple tasks concurrently. Here's a basic example of +creating and starting threads using :class:`~threading.Thread`:: + + import threading + import time + + def crawl(link, delay=3): + print(f"crawl started for {link}") + time.sleep(delay) # Blocking I/O (simulating a network request) + print(f"crawl ended for {link}") + + links = [ + "https://python.org", + "https://docs.python.org", + "https://peps.python.org", + ] + + # Start threads for each link + threads = [] + for link in links: + # Using `args` to pass positional arguments and `kwargs` for keyword arguments + t = threading.Thread(target=crawl, args=(link,), kwargs={"delay": 2}) + threads.append(t) + + # Start each thread + for t in threads: + t.start() + + # Wait for all threads to finish + for t in threads: + t.join() + .. versionchanged:: 3.7 This module used to be optional, it is now always available. @@ -45,7 +91,25 @@ level :mod:`_thread` module. However, threading is still an appropriate model if you want to run multiple I/O-bound tasks simultaneously. -.. include:: ../includes/wasm-notavail.rst +GIL and performance considerations +---------------------------------- + +Unlike the :mod:`multiprocessing` module, which uses separate processes to +bypass the :term:`global interpreter lock` (GIL), the threading module operates +within a single process, meaning that all threads share the same memory space. +However, the GIL limits the performance gains of threading when it comes to +CPU-bound tasks, as only one thread can execute Python bytecode at a time. +Despite this, threads remain a useful tool for achieving concurrency in many +scenarios. + +As of Python 3.13, experimental :term:`free-threaded <free threading>` builds +can disable the GIL, enabling true parallel execution of threads, but this +feature is not available by default (see :pep:`703`). + +.. TODO: At some point this feature will become available by default. + +Reference +--------- This module defines the following functions: @@ -62,7 +126,7 @@ This module defines the following functions: Return the current :class:`Thread` object, corresponding to the caller's thread of control. If the caller's thread of control was not created through the - :mod:`threading` module, a dummy thread object with limited functionality is + :mod:`!threading` module, a dummy thread object with limited functionality is returned. The function ``currentThread`` is a deprecated alias for this function. @@ -157,13 +221,13 @@ This module defines the following functions: .. index:: single: trace function - Set a trace function for all threads started from the :mod:`threading` module. + 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:`~Thread.run` method is called. .. function:: settrace_all_threads(func) - Set a trace function for all threads started from the :mod:`threading` module + Set a trace function for all threads started from the :mod:`!threading` module and all Python threads that are currently executing. The *func* will be passed to :func:`sys.settrace` for each thread, before its @@ -186,13 +250,13 @@ This module defines the following functions: .. index:: single: profile function - Set a profile function for all threads started from the :mod:`threading` module. + 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:`~Thread.run` method is called. .. function:: setprofile_all_threads(func) - Set a profile function for all threads started from the :mod:`threading` module + Set a profile function for all threads started from the :mod:`!threading` module and all Python threads that are currently executing. The *func* will be passed to :func:`sys.setprofile` for each thread, before its @@ -257,8 +321,8 @@ when implemented, are mapped to module-level functions. All of the methods described below are executed atomically. -Thread-Local Data ------------------ +Thread-local data +^^^^^^^^^^^^^^^^^ Thread-local data is data whose values are thread specific. If you have data that you want to be local to a thread, create a @@ -389,8 +453,8 @@ affects what we see:: .. _thread-objects: -Thread Objects --------------- +Thread objects +^^^^^^^^^^^^^^ The :class:`Thread` class represents an activity that is run in a separate thread of control. There are two ways to specify the activity: by passing a @@ -645,8 +709,8 @@ since it is impossible to detect the termination of alien threads. .. _lock-objects: -Lock Objects ------------- +Lock objects +^^^^^^^^^^^^ A primitive lock is a synchronization primitive that is not owned by a particular thread when locked. In Python, it is currently the lowest level @@ -738,8 +802,8 @@ All methods are executed atomically. .. _rlock-objects: -RLock Objects -------------- +RLock objects +^^^^^^^^^^^^^ A reentrant lock is a synchronization primitive that may be acquired multiple times by the same thread. Internally, it uses the concepts of "owning thread" @@ -848,8 +912,8 @@ call release as many times the lock has been acquired can lead to deadlock. .. _condition-objects: -Condition Objects ------------------ +Condition objects +^^^^^^^^^^^^^^^^^ A condition variable is always associated with some kind of lock; this can be passed in or one will be created by default. Passing one in is useful when @@ -1026,8 +1090,8 @@ item to the buffer only needs to wake up one consumer thread. .. _semaphore-objects: -Semaphore Objects ------------------ +Semaphore objects +^^^^^^^^^^^^^^^^^ This is one of the oldest synchronization primitives in the history of computer science, invented by the early Dutch computer scientist Edsger W. Dijkstra (he @@ -1107,7 +1171,7 @@ Semaphores also support the :ref:`context management protocol <with-locks>`. .. _semaphore-examples: -:class:`Semaphore` Example +:class:`Semaphore` example ^^^^^^^^^^^^^^^^^^^^^^^^^^ Semaphores are often used to guard resources with limited capacity, for example, @@ -1135,8 +1199,8 @@ causes the semaphore to be released more than it's acquired will go undetected. .. _event-objects: -Event Objects -------------- +Event objects +^^^^^^^^^^^^^ This is one of the simplest mechanisms for communication between threads: one thread signals an event and other threads wait for it. @@ -1192,8 +1256,8 @@ method. The :meth:`~Event.wait` method blocks until the flag is true. .. _timer-objects: -Timer Objects -------------- +Timer objects +^^^^^^^^^^^^^ 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` @@ -1230,8 +1294,8 @@ For example:: only work if the timer is still in its waiting stage. -Barrier Objects ---------------- +Barrier objects +^^^^^^^^^^^^^^^ .. versionadded:: 3.2 |