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Fix SIGCHLD race in signal handler setup #5210

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lifubang merged 1 commit into from
Apr 2, 2026
+7 −4
Merged

Fix SIGCHLD race in signal handler setup #5210

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11 changes: 7 additions & 4 deletions signals.go
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Original file line number Diff line number Diff line change
Expand Up @@ -26,14 +26,17 @@ func newSignalHandler(enableSubreaper bool, notifySocket *notifySocket) chan *si
}
}
handler := make(chan *signalHandler)

// Ensure that we have a large buffer size so that we do not miss any
// signals in case we are not processing them fast enough.
s := make(chan os.Signal, signalBufferSize)

// signal.Notify is actually quite expensive, as it has to configure the
// signal mask and add signal handlers for all signals (all ~65 of them).
// So, defer this to a background thread while doing the rest of the io/tty
// setup.
// setup, except for SIGCHLD which is very important (see #5208).
signal.Notify(s, unix.SIGCHLD)
go func() {
// ensure that we have a large buffer size so that we do not miss any
// signals in case we are not processing them fast enough.
s := make(chan os.Signal, signalBufferSize)
// handle all signals for the process.
signal.Notify(s)
handler <- &signalHandler{
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