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pybind / pybind11

Seamless operability between C++11 and Python
https://pybind11.readthedocs.io/
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Do not check the GIL/decref object if the Python runtime is dead #4769

Closed albanD closed 1 year ago

albanD commented 1 year ago

Description

This change guards GIL check and decref for objects behind a check that the Python runtime still exists. This can happen if a static variable outlives the python runtime and is destroyed later. This happens when the user uses the recommended way to create custom exceptions from https://pybind11.readthedocs.io/en/stable/advanced/exceptions.html as static py::exception<MyCustomException> exc(m, "MyCustomError");

In particular, this change fixes the segfault described at https://github.com/pytorch/pytorch/pull/106083 (when working on upgrading PyTorch to 3.12)

Suggested changelog entry:

Skip calling Python decref when the Python runtime is already dead.

albanD commented 1 year ago

We don't have the final conclusion yet but we're definitely not going to do this (fixing the lifetime of the obejcts instead). See https://github.com/pytorch/pytorch/pull/106401 for more details on the discussion.