mirror of https://github.com/scrapy/scrapy.git
61 lines
2.2 KiB
ReStructuredText
61 lines
2.2 KiB
ReStructuredText
.. _using-asyncio:
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=======
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asyncio
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=======
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.. versionadded:: 2.0
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Scrapy has partial support for :mod:`asyncio`. After you :ref:`install the
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asyncio reactor <install-asyncio>`, you may use :mod:`asyncio` and
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:mod:`asyncio`-powered libraries in any :doc:`coroutine <coroutines>`.
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.. warning:: :mod:`asyncio` support in Scrapy is experimental, and not yet
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recommended for production environments. Future Scrapy versions
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may introduce related changes without a deprecation period or
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warning.
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.. _install-asyncio:
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Installing the asyncio reactor
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==============================
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To enable :mod:`asyncio` support, set the :setting:`TWISTED_REACTOR` setting to
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``'twisted.internet.asyncioreactor.AsyncioSelectorReactor'``.
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If you are using :class:`~scrapy.crawler.CrawlerRunner`, you also need to
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install the :class:`~twisted.internet.asyncioreactor.AsyncioSelectorReactor`
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reactor manually. You can do that using
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:func:`~scrapy.utils.reactor.install_reactor`::
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install_reactor('twisted.internet.asyncioreactor.AsyncioSelectorReactor')
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.. _using-custom-loops:
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Using custom asyncio loops
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==========================
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You can also use custom asyncio event loops with the asyncio reactor. Set the
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:setting:`ASYNCIO_EVENT_LOOP` setting to the import path of the desired event loop class to
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use it instead of the default asyncio event loop.
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.. _asyncio-await-dfd:
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Awaiting on Deferreds
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=====================
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When the asyncio reactor isn't installed, you can await on Deferreds in the
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coroutines directly. When it is installed, this is not possible anymore, due to
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specifics of the Scrapy coroutine integration (the coroutines are wrapped into
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:class:`asyncio.Future` objects, not into
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:class:`~twisted.internet.defer.Deferred` directly), and you need to wrap them into
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Futures. Scrapy provides two helpers for this:
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.. autofunction:: scrapy.utils.defer.deferred_to_future
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.. autofunction:: scrapy.utils.defer.maybe_deferred_to_future
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.. tip:: If you need to use these functions in code that aims to be compatible
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with lower versions of Scrapy that do not provide these functions,
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down to Scrapy 2.0 (earlier versions do not support
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:mod:`asyncio`), you can copy the implementation of these functions
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into your own code.
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