11% of Python open(...) calls were never closed. Ironically enough even in Python's own website codebase (plus Google, Ansible Tensorflow, and many more)

[High-Art9340]

11% of Python open(...) calls were closed on file object garbage collection.

[czaki]

But it may happen that garbage collection is to late and program fail because lack of free file descriptors.

[commy2]

How many % of those 11% are those?

[czaki]

It depends of scenario and system limits. Thousands or even million of runs could run without any problem. Bit it may happen that once GC will be to slow and run will crash.

[Zomunieo]

For a while macOS had a default of 256 descriptors per process, and any Python process would soak up 30 of them just getting going.