asyncio — Scrapy documentation

asyncio

New in version 2.0.

Scrapy has partial support for asyncio. After you install the asyncio reactor, you may use asyncio and asyncio-powered libraries in any coroutine.

Installing the asyncio reactor

To enable asyncio support, set the :setting:`TWISTED_REACTOR` setting to 'twisted.internet.asyncioreactor.AsyncioSelectorReactor'.

If you are using CrawlerRunner, you also need to install the AsyncioSelectorReactor reactor manually. You can do that using install_reactor():

install_reactor('twisted.internet.asyncioreactor.AsyncioSelectorReactor')

Using custom asyncio loops

You can also use custom asyncio event loops with the asyncio reactor. Set the :setting:`ASYNCIO_EVENT_LOOP` setting to the import path of the desired event loop class to use it instead of the default asyncio event loop.

Awaiting on Deferreds

When the asyncio reactor isn’t installed, you can await on Deferreds in the coroutines directly. When it is installed, this is not possible anymore, due to specifics of the Scrapy coroutine integration (the coroutines are wrapped into asyncio.Future objects, not into Deferred directly), and you need to wrap them into Futures. Scrapy provides two helpers for this:

Tip

If you need to use these functions in code that aims to be compatible with lower versions of Scrapy that do not provide these functions, down to Scrapy 2.0 (earlier versions do not support asyncio), you can copy the implementation of these functions into your own code.