fix(agent/reaper): prevent reaper from stealing child exit status#22866
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fix(agent/reaper): prevent reaper from stealing child exit status#22866
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ForkReap starts a reaper goroutine that calls Wait4(-1, WNOHANG), which reaps any child. This raced with ForkReap's own Wait4(pid) for the direct child, causing ECHILD errors. Use the reapLock that go-reap already supports: hold a read lock during our Wait4(pid) so the reaper's write lock blocks until we have collected the child's status.
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ForkReap starts a reaper goroutine that calls
Wait4(-1, WNOHANG), whichreaps any child. This raced with ForkReap's own
Wait4(pid)for the directchild, causing ECHILD ("no child processes") errors in
TestForkReapExitCodesand
TestReapInterrupt.The fix uses the
reapLockparameter thatgo-reapalready supports: we holda read lock during our
Wait4(pid)so the reaper's write lock blocks until wehave collected the child's status. This keeps the reaper active for zombie
cleanup while the child is running, but prevents it from stealing the direct
child's exit status.