[3.7] bpo-26819: Prevent proactor double read on resume (GH-6921)#7004
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The proactor event loop has a race condition when reading with pausing/resuming. `resume_reading()` unconditionally schedules the read function to read from the current future. If `resume_reading()` was called before the previously scheduled done callback fires, this results in two attempts to get the data from the most recent read and an assertion failure. This commit tracks whether or not `resume_reading` needs to reschedule the callback to restart the loop, preventing a second attempt to read the data. (cherry picked from commit 4151061) Co-authored-by: CtrlZvi <viz+github@flippedperspective.com>
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asvetlov
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May 20, 2018
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The proactor event loop has a race condition when reading with
pausing/resuming.
resume_reading()unconditionally schedules the readfunction to read from the current future. If
resume_reading()wascalled before the previously scheduled done callback fires, this results
in two attempts to get the data from the most recent read and an
assertion failure. This commit tracks whether or not
resume_readingneeds to reschedule the callback to restart the loop, preventing a
second attempt to read the data.
(cherry picked from commit 4151061)
Co-authored-by: CtrlZvi viz+github@flippedperspective.com
https://bugs.python.org/issue26819