Running asyncio.run() more than once

[Clint Olsen]

On Monday, March 13, 2023 at 11:32:23 PM UTC-7, Clint Olsen wrote:
> We have an application that involves submitting hundreds to thousands of jobs to a shared computing resource, and we're using asyncio to do so because it is far less overhead than threading or multiprocessing for the bookkeeping required to keep track of all these jobs. It makes extensive use of asyncio.create_subprocess_exec(). This was developed mostly in Python 3.9.7. 

Good news! I did end up finding the source of the problem. I kept looking for the use of global data as a potential source of bugs and didn't really find anything there. I did fix some potential signal handler problems. However I had this particular piece of code that I needed to follow my processes.

        watcher = asyncio.FastChildWatcher()
        watcher.attach_loop(asyncio.get_event_loop())
        asyncio.set_child_watcher(watcher)

Since async reuses the same event loop on successive calls, doing this again is bad. I just needed to ensure I only set this once.

Thanks,

-Clint