To ASGIMiddleware or not

[dineshbvadhia]

The asgiref sync-to-async and async-to-sync function decoraters are used extensively in our code. After reading the Starlette pure-asgi-middleware documentation https://www.starlette.io/middleware/#pure-asgi-middleware, should we be using the example asgiref-specific ASGIMIddleware?

[adriangb]

I don't get how those decorators are related to the choice of middleware.

But generally to minimize issues I would:

• Do as much in async code as you can
• Minimize and isolate sync code and run in it in worker threads. Be careful of thread limits, you can cause deadlocks.
• Be careful with blocking the event loop by running sync code in it.
• Use pure ASGI middleware instead of BaseHTTPMiddelware or the @app.middleware decorator. If you're using FastAPI async dependencies are a good replacement for one-off simple middleware.

[dineshbvadhia]

Using asgiref, my code already follows:

• Do as much in async code as you can
• Minimize and isolate sync code and run in it in worker threads. Be careful of thread limits, you can cause deadlocks.
• Be careful with blocking the event loop by running sync code in it.

The question is: Do I also need to configure Starlette with the example asgiref-specific ASGIMIddleware or is this a silly question?

[adriangb]

Using asgiref, my code already follows:

Using asgiref or not doesn't guarantee you are following those principles.

Do I also need to configure Starlette with the example asgiref-specific ASGIMIddleware or is this a silly question?

What is "example asgiref-specific ASGIMIddleware"?

[dineshbvadhia]

Going to close the discussion because I need to get my head around Starlette's ASGIMiddleware. Thanks for hanging in :)