[fiddlerwoaroof]

Another way to do this that covers more sources of non-determinism would be to run your python code under Meta’s Hermit: https://developers.facebook.com/blog/post/2022/11/22/hermit-...

[amnqrt]

Well, I never had issues with finding threading bugs on a normal Linux. The flakiness in Meta software tests, at least of the open source published kind, is that the code bases are a mess and are rewritten every two weeks, because apparently LOC is the measure of success.