Make asyncio reactor a default

[kmike]

Should we make 'twisted.internet.asyncioreactor.AsyncioSelectorReactor' a default? If so, should it be default in Scrapy 2.7, or is it too soon? We can start with making it default in the project template; it looks safe enough for Scrapy 2.7, or is it?

The reactor was introduced in Scrapy 2.0; I don't recall any particular issues reported about it. It'd be good to have it as a default eventually, because there are more an more Scrapy plugins which rely on asyncio libraries.

[pablohoffman]

Are there any big users/projects using the asyncio reactor @kmike?

[kmike]

@pablohoffman packages like

• https://github.com/scrapy-plugins/scrapy-playwright/,
• https://github.com/scrapinghub/scrapy-autoextract,
• https://github.com/scrapy-plugins/scrapy-zyte-api

require asyncio reactor; any Scrapy project which uses one of these extensions needs to switch to ascynio reactor.

[elacuesta]

Related: #5103

[pablohoffman]

Thanks. As far as I'm concerned, it makes sense, and changing the default project template is a good way to start.