mirror of https://github.com/python/cpython
111 lines
2.7 KiB
ReStructuredText
111 lines
2.7 KiB
ReStructuredText
:mod:`asyncio` --- Asynchronous I/O
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===================================
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.. module:: asyncio
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:synopsis: Asynchronous I/O.
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-------------------------------
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.. sidebar:: Hello World!
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::
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import asyncio
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async def main():
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print('Hello ...')
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await asyncio.sleep(1)
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print('... World!')
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asyncio.run(main())
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asyncio is a library to write **concurrent** code using
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the **async/await** syntax.
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asyncio is used as a foundation for multiple Python asynchronous
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frameworks that provide high-performance network and web-servers,
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database connection libraries, distributed task queues, etc.
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asyncio is often a perfect fit for IO-bound and high-level
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**structured** network code.
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asyncio provides a set of **high-level** APIs to:
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* :ref:`run Python coroutines <coroutine>` concurrently and
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have full control over their execution;
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* perform :ref:`network IO and IPC <asyncio-streams>`;
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* control :ref:`subprocesses <asyncio-subprocess>`;
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* distribute tasks via :ref:`queues <asyncio-queues>`;
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* :ref:`synchronize <asyncio-sync>` concurrent code;
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Additionally, there are **low-level** APIs for
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*library and framework developers* to:
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* create and manage :ref:`event loops <asyncio-event-loop>`, which
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provide asynchronous APIs for :meth:`networking <loop.create_server>`,
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running :meth:`subprocesses <loop.subprocess_exec>`,
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handling :meth:`OS signals <loop.add_signal_handler>`, etc;
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* implement efficient protocols using
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:ref:`transports <asyncio-transports-protocols>`;
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* :ref:`bridge <asyncio-futures>` callback-based libraries and code
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with async/await syntax.
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You can experiment with an ``asyncio`` concurrent context in the REPL:
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.. code-block:: pycon
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$ python -m asyncio
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asyncio REPL ...
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Use "await" directly instead of "asyncio.run()".
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Type "help", "copyright", "credits" or "license" for more information.
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>>> import asyncio
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>>> await asyncio.sleep(10, result='hello')
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'hello'
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.. include:: ../includes/wasm-notavail.rst
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.. We use the "rubric" directive here to avoid creating
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the "Reference" subsection in the TOC.
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.. rubric:: Reference
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.. toctree::
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:caption: High-level APIs
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:maxdepth: 1
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asyncio-runner.rst
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asyncio-task.rst
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asyncio-stream.rst
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asyncio-sync.rst
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asyncio-subprocess.rst
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asyncio-queue.rst
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asyncio-exceptions.rst
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.. toctree::
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:caption: Low-level APIs
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:maxdepth: 1
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asyncio-eventloop.rst
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asyncio-future.rst
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asyncio-protocol.rst
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asyncio-policy.rst
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asyncio-platforms.rst
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asyncio-extending.rst
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.. toctree::
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:caption: Guides and Tutorials
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:maxdepth: 1
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asyncio-api-index.rst
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asyncio-llapi-index.rst
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asyncio-dev.rst
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.. note::
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The source code for asyncio can be found in :source:`Lib/asyncio/`.
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