Aleksandr Efimov created IMPALA-15601:
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Summary: Analyzer DEBUG cache statistics can delay planning
Key: IMPALA-15601
URL: https://issues.apache.org/jira/browse/IMPALA-15601
Project: IMPALA
Issue Type: Bug
Reporter: Aleksandr Efimov
`Analyzer.logCacheStats()` calls `MemoryMeter.measureDeep()` for every
null-slots cache key on the synchronous planning path when DEBUG is enabled.
The histogram reservoir limits stored samples, but does not bound measurement
cost.
One request finished distributed planning in 0.86 seconds but returned from
planning after about 268 seconds. A JVM snapshot showed this deep-measurement
path during the delay; its total contribution was not measured.
Please avoid or reliably bound deep object traversal while retaining cheap
cache statistics. Sampling entries alone may be insufficient because one
measurement can be expensive.
Workaround: `org.apache.impala.analysis.Analyzer=INFO`. Performance after
applying it has not been verified.
Introduced by IMPALA-12800. The deployed binary revision was not independently
confirmed.
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