Restore OS-level signal handler after changing it in plt.pause() #29947
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Specifically https://github.com/python/cpython/blob/ce31ae5209c976d28d1c21fcbb06c0ae5e50a896/Modules/signalmodule.c#L535-L538 is the source of the problem as (somewhat reasonably) CPython unconditionally takes over the underlying signal handling machinery when you register a Python side signal handler (if CPython does not do that it can not call the user provided handler for the user. Contrary to prompt-toolkit, we already have a fair amount of compiled code I would rather see a helper in https://github.com/matplotlib/matplotlib/blob/main/src/_c_internal_utils.cpp. This is both to avoid having ctypes in generally and because Python can be built without the ctypes module. Signal handling is a fun rabbit hole that I was sure we had already gotten to the bottom of (when we added checking to making sure that handler set from julia didn't get broken). |
Previously,
cysignalssignal handlers are broken afterplt.pause()is called. More explanation can be found in sagemath/sage#39601 and sagemath/cysignals#228The change was adapted from prompt-toolkit/python-prompt-toolkit#1822
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