[3.13] gh-87744: fix waitpid race while calling send_signal in asyncio (GH-121126) #121194
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…pythonGH-121126) asyncio earlier relied on subprocess module to send signals to the process, this has some drawbacks one being that subprocess module unnecessarily calls waitpid on child processes and hence it races with asyncio implementation which internally uses child watchers. To mitigate this, now asyncio sends signals directly to the process without going through the subprocess on non windows systems. On Windows it fallbacks to subprocess module handling but on windows there are no child watchers so this issue doesn't exists altogether. (cherry picked from commit bd473aa) Co-authored-by: Kumar Aditya <kumaraditya@python.org>
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This was referenced Jul 1, 2024
With asyncio subprocess, send_signal() and the child process watcher will both call waitpid()
#87744
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bedevere-app
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topic-asyncio
type-bug
kumaraditya303
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Jul 1, 2024
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asyncio earlier relied on subprocess module to send signals to the process, this has some drawbacks one being that subprocess module unnecessarily calls waitpid on child processes and hence it races with asyncio implementation which internally uses child watchers. To mitigate this, now asyncio sends signals directly to the process without going through the subprocess on non windows systems. On Windows it fallbacks to subprocess module handling but on windows there are no child watchers so this issue doesn't exists altogether.
(cherry picked from commit bd473aa)
Co-authored-by: Kumar Aditya kumaraditya@python.org