How do I use AsyncIOScheduler to execute time-consuming I/O operations without blocking other tasks

[pwallk]

Things to check first

• I have checked that my issue does not already have a solution in the FAQ

• I have searched the existing issues and didn't find my bug already reported there

• I have checked that my bug is still present in the latest release

Version

3.10.4

What happened?

I'm not familiar with asyncio, When I use AsyncIOScheduler in FastAPI to perform time-consuming IO operations, I block other asyncio tasks as well as the fastapi interface

How can we reproduce the bug?

async def init_scheduler(app: FastAPI):
    scheduler = AsyncIOScheduler(
        job_defaults={
            'coalesce': True,
            'max_instances': 10,
            'misfire_grace_time': 10
        },
        executors={
            'default': AsyncIOExecutor(),
            'threadpool': ThreadPoolExecutor(10),
            'processpool': ProcessPoolExecutor(2)
        }
    )
    app.state.scheduler = scheduler
    scheduler.add_job(job1, args=[app], trigger='interval', seconds=1)
    scheduler.add_job(job2, args=[app], trigger='interval', seconds=1)
    scheduler.start()

async def job1(app: FastAPI):
    # do time-consuming tasks

async def job1(app: FastAPI):
    # do something

[agronholm]

This is async 101. AsyncIOExecutor should only be used for async jobs. You already have alternative executors configured – why not use them for those blocking operations?

And next time, open a discussion instead of reporting a bug when you're asking for help on how to use the scheduler.

[agronholm]

You haven't shown what job1 and job2 do, and I assume you're running synchronous operations there that block the event loop. So perhaps use those other executors for those jobs, and make the target functions synchronous.