Mark Robert Miller created SOLR-18284:
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Summary: Fix load-average and memory circuit breakers
Key: SOLR-18284
URL: https://issues.apache.org/jira/browse/SOLR-18284
Project: Solr
Issue Type: Bug
Reporter: Mark Robert Miller
Load-average and memory circuit breakers were doing more harm than good under
high concurrency.
LoadAverageCircuitBreaker called OperatingSystemMXBean.getSystemLoadAverage()
on every request. The OS load average is a one-minute moving average, so
re-polling it per-request is wasted work - and when many requests arrived
concurrently, the syscall stampede hammered the CPU, which is the condition
this breaker exists to prevent rather than cause.
MemoryCircuitBreaker sampled MemoryMXBean.getHeapMemoryUsage().getUsed() on a
30-second moving average. With a generational collector that signal climbs
toward max between collections during normal operation; the breaker would trip
on transient pre-GC peaks that GC was about to reclaim.
* I extracted these from the experimental circuit breaker overhaul PR.
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