perf(core): Use fixed-delay scheduling for performance collector (JAVA-555)#5524
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perf(core): Use fixed-delay scheduling for performance collector (JAVA-555)#5524runningcode wants to merge 4 commits into
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Switch the transaction collection timer from scheduleAtFixedRate to schedule. Fixed-rate scheduling fires rapid catch-up executions after a delay or GC pause, which the old code guarded against with a 10ms skip check. Fixed-delay scheduling spaces each collection 100ms after the previous one finishes, so the catch-up bursts cannot happen and the guard, its timestamp field, and the stale comment are no longer needed. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Jun 10, 2026
| new TimerTask() { | ||
| @Override | ||
| public void run() { | ||
| long now = System.currentTimeMillis(); |
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The issue is that scheduleAtFixedRate could schedule thousands of tasks in a row if the system goes in to deep sleep but then we guard against it using this System.currentTimeMillis() which isn't a monotonic clock meaning it could go forwards and then guard is broken allowing thousands of tasks to run.
The performance collector now uses fixed-delay scheduling, so the timer verifications assert schedule(...) rather than scheduleAtFixedRate(...). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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📜 Description
Switch the transaction collection timer in
DefaultCompositePerformanceCollectorfromTimer.scheduleAtFixedRatetoTimer.schedule(fixed-delay scheduling).Fixes JAVA-555.
💡 Motivation and Context
scheduleAtFixedRateschedules tasks relative to the initial start time, so after a delay or GC pause it fires a burst of rapid catch-up executions to "make up" for missed runs. The old code defended against this with a 10ms skip check, since collections spaced closer than that are not meaningful. In addition, it is usingSystem.currentTimeMillis()which isn't a monotonic clock meaning it could go forwards and then guard is broken allowing all the tasks to run.scheduleuses fixed-delay scheduling: each collection is scheduled 100ms after the previous one finishes. Catch-up bursts can no longer happen, so the guard and its supporting state are redundant. The result is more even collection spacing and simpler code.📝 Checklist
sendDefaultPIIis enabled.🔮 Next steps