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publish: NewTimer+Stop instead of time.After in the fan-out hot path #35

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Merged
matthew-pilot merged 1 commit into from
Jul 29, 2026
Merged

publish: NewTimer+Stop instead of time.After in the fan-out hot path #35

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11 changes: 10 additions & 1 deletion service.go
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Original file line number Diff line number Diff line change
Expand Up @@ -408,6 +408,8 @@ func (b *broker) publishWith(evt *Event, sender *subscriber, write eventWriter)
}
done <- err
}()
writeTimeout := time.NewTimer(publishWriteTimeout)
defer writeTimeout.Stop()
select {
case err := <-done:
if err == nil {
Expand All @@ -423,7 +425,14 @@ func (b *broker) publishWith(evt *Event, sender *subscriber, write eventWriter)
dead = append(dead, s)
deadMu.Unlock()
}
case <-time.After(publishWriteTimeout):
// NewTimer + Stop, not time.After. This runs in a goroutine
// spawned per subscriber per event, and time.After pins its
// timer in the runtime heap for the full publishWriteTimeout
// even when the write completes immediately. At the 100 ev/s
// publish limit with S subscribers that is up to 500*S live
// timers in steady state — 50k at S=100 — purely as GC and
// timer-heap pressure.
case <-writeTimeout.C:
if s.publishFailures.Add(1) >= maxConsecutivePublishFailures {
slog.Debug("eventstream subscriber removed after write timeout",
"remote", s.remote(),
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