run_parallel.py sometimes hangs

[scottcanoe]

Describe the bug

When using run_parallel.py, threads/processes sometimes fail to close after the experiment has run. This occurs just before post-parallel cleanup. Whether the program hangs at this point seems random, and it occurs for me roughly half of the time.

I'm on an Apple M3 Max, Sequoia 15.1.1, using miniconda in accordance with Monty's installation instructions. This issue only occurs when I run experiments locally.

Strangely, this only started happening a couple of weeks ago, so perhaps it's tied to a software update. I've tried closing basically every app on my computer with the thinking that some resource isn't being released that's preventing threads/processes in a waiting state, but so I haven't found any factors that affect this behavior.

I'll post any updates here as I learn more about the problem.