#32172: Adapt signals to allow async handlers
-------------------------------------+-------------------------------------
Reporter: Carlton Gibson | Owner:
| Konstantin Volkov
Type: New feature | Status: assigned
Component: Core (Other) | Version: master
Severity: Normal | Resolution:
Keywords: async | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Description changed by Carlton Gibson:
Old description:
> Currently (circa 3.1) we have a couple of `sync_to_async()` usages in
> [https://github.com/django/django/blob/009fddc96b88a9aee1232d6a2637f2970fdcfb50/django/core/handlers/asgi.py#L154
> the main line of `ASGIHandler.__call__()`], for the request life cycle
> signals:
>
> {{{
> await sync_to_async(signals.request_started.send,
> thread_sensitive=True)(sender=self.__class__, scope=scope)
> }}}
>
> Much as is done of the middleware,
> [https://github.com/django/django/blob/76181308fb02e67794d0cc1471766a5d7e4c877e/django/core/handlers/base.py#L26
> adapting to accept either synchronous or asynchronous middleware
> classes], it would be good to be able to push that `sync_to_async()` call
> down into the `send()` method, allowing signal handlers to be either sync
> (as now) or async coroutines.
>
> This would give us the option of having a completely async request
> pathway, if we were to remove all synchronous middleware and signal
> handlers.
>
> There will need to be some discussion, perhaps on a PR, or the
> [https://forum.djangoproject.com/c/internals/async/8 Forum's Async
> category] but opening this ticket to track efforts.
New description:
Currently (circa 3.1) we have a couple of `sync_to_async()` usages in
[https://github.com/django/django/blob/009fddc96b88a9aee1232d6a2637f2970fdcfb50/django/core/handlers/asgi.py#L154
the main line of `ASGIHandler.__call__()`], for the request life cycle
signals:
{{{
await sync_to_async(signals.request_started.send,
thread_sensitive=True)(sender=self.__class__, scope=scope)
}}}
Much as is done of the middleware,
[https://github.com/django/django/blob/76181308fb02e67794d0cc1471766a5d7e4c877e/django/core/handlers/base.py#L26
adapting to accept either synchronous or asynchronous middleware classes],
it would be good to be able to push that `sync_to_async()` call down into
the `send()` method, allowing signal handlers to be either sync (as now)
or async coroutines.
This would give us the option of having a completely async request
pathway, if we were to remove all synchronous middleware and signal
handlers.
There will need to be some discussion of exact implementation, perhaps on
a PR, or the [https://forum.djangoproject.com/c/internals/async/8 Forum's
Async category] but opening this ticket to track efforts.
--
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Ticket URL: <https://code.djangoproject.com/ticket/32172#comment:3>
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