Tolerate spurious wakeups on the background worker thread.#350
Merged
iCharlesHu merged 1 commit intoJul 9, 2026
Merged
Conversation
Subprocess spawns run on a single shared background worker thread that sleeps on a POSIX condition variable while its work queue is empty. pthread_cond_wait is permitted by POSIX to return without a matching signal and does so in practice on Linux when the waiting thread is interrupted by a signal (aka 'spurious wakeup'). Update the wait logic by looping instead of branching, so a spurious wakeup with an empty queue simply re-checks the predicate and goes back to sleep. This change prevents the worker thread from exiting prematurely, which leads to hangs and continuation leaks.
jakepetroules
approved these changes
Jul 9, 2026
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Subprocess spawns run on a single shared background worker thread that sleeps on a POSIX condition variable while its work queue is empty.
pthread_cond_waitis permitted by POSIX to return without a matching signal and does so in practice on Linux when the waiting thread is interrupted by a signal (aka 'spurious wakeup').Update the wait logic by looping instead of branching, so a spurious wakeup with an empty queue simply re-checks the predicate and goes back to sleep. This change prevents the worker thread from exiting prematurely, which leads to hangs and continuation leaks.
Resolves: #348