Method to run code in a thread

I’d like to add a convenient method to execute in job in a thread.

It would probably be added to message pump (used by app / widgets).

It should allow a method to be called with arbitrary parameters, and should return an awaitable.

await self.call_threaded(my_code, "foo", "bar")

I can see this being used for jobs such as reading from disk (which at the moment blocks the vent loop).

Some considerations: a thread pool may be appropriate. We don’t want this to be unbounded and potentially launch an unlimited number of threads. It should probably work with both async and sync functions, which will require a little inspection. If you want to tackle this, please discuss your ideas here first.

[ksamuel]

Asyncio already provides facilities for that:

https://docs.python.org/3/library/asyncio-eventloop.html#asyncio.loop.run_in_executor

However, we could provide a wrapper that will:

• get_event_loop automatically
• use the default executor instead of requesting None as a first parameter
• wrap the callable and any excess param into functiools.partial prior to passing it to the thread
• if the callable returns a coroutine or if passed an awaitable, we call create_task from a different event loop within the wrapper and pass it to run_until_complete

What’s message pump ?

Edit : got it, message pump seems to be a queue based pub/sub infra to propagate event in the app.

[tusharsadhwani]

I think App.run is important to keep things simple by default, some people don’t know anything about asyncio.

I’d suggest showing both approaches, asyncio one probably in an advanced section somewhere.