gh-145638: Add signal.get_wakeup_fd()#145726
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Add signal.get_wakeup_fd() to return the current wakeup file descriptor without modifying it. This avoids the race condition inherent in the current workaround of calling set_wakeup_fd(-1) followed by set_wakeup_fd(fd) to read the current value. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
aisk
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Mar 10, 2026
| attempting to call it from other threads will cause a :exc:`ValueError` | ||
| exception to be raised. | ||
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| .. versionadded:: 3.15 |
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| .. versionadded:: 3.15 | |
| .. versionadded:: next |
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Fixes #145638
Summary
Adds
signal.get_wakeup_fd()to return the current wakeup file descriptor without modifying it.Currently, the only way to read the wakeup fd is via
signal.set_wakeup_fd(-1)followed bysignal.set_wakeup_fd(fd), which creates a race condition window where signals can be lost. The new function simply readswakeup.fdwithout any side effects.Changes
Modules/signalmodule.c: Newsignal_get_wakeup_fd_implfunction using Argument Clinic. Same main-thread check asset_wakeup_fd. Returnswakeup.fddirectly.Doc/library/signal.rst: Documentation for the new function.Lib/test/test_signal.py: Tests verifyingget_wakeup_fd()returns -1 when unset, the correct fd afterset_wakeup_fd(), and -1 again after clearing.Test plan
test_get_wakeup_fdadded covering set/get/clear cycleThis contribution was developed with AI assistance (Claude Code).
signal.get_wakeup_fd()#145638📚 Documentation preview 📚: https://cpython-previews--145726.org.readthedocs.build/