[1.8] fix race condition and KeyError exception in executor#9353
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[1.8] fix race condition and KeyError exception in executor#9353
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Previously, it was possible that `Executor.supports_fancy_output` would flip-flop between True and False if a thread was updating a section. This could lead to a crash when an operation got different reponses as it made progress. `Executor.supports_fancy_output` reflects the value of the underlying cleo Formatter used by the Output object. The Formatter is shared by any SectionOutputs derived by that Output object. If a thread (tA) is in the middle of `Formatter.remove_format` while updating a section, the flag to show decorator support is temporarily toggled off and then restored. This opens a window where another thread could get an incorrect answer when querying `supports_fancy_output`. If a parallel thread (tB) queries `supports_fancy_output` and sees it is False, the operation will not get added to the Executor's _sections dictionary. If tB's operation progresses after tA has restored the decorator value and attempts to write out progress information it will call `Executor._write`, see that `supports_fancy_output` is now True and attempt to find the operation in the _sections dictionary, however there will not be an entry for that operation due to the earlier query that returned False. This causes tB to throw a KeyError and causes the install to shutdown. Now, the Executor queries and caches whether the Output is decorated during init. This value is used in `supports_fancy_output` so as to not be affected by changes to the underlying Formatter object during section updates. Signed-off-by: Vincent Fazio <vfazio@gmail.com> (cherry picked from commit acaf9c8)
radoering
approved these changes
Apr 30, 2024
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This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs. |
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Backport acaf9c8 from #9335.