Alexis Daboville created HADOOP-16248:
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Summary: Fix MutableQuantiles memory leak
Key: HADOOP-16248
URL: https://issues.apache.org/jira/browse/HADOOP-16248
Project: Hadoop Common
Issue Type: Bug
Affects Versions: 2.9.2
Reporter: Alexis Daboville
Attachments: mutable-quantiles-leak.png, mutable-quantiles.patch
In some circumstances (high GC, high CPU usage, creating lots of
S3AFileSystem) it is possible for MutableQuantiles::scheduler [1] to fall
behind processing tasks that are submitted to it; because tasks are
submitted on a regular schedule, the unbounded queue backing the
{{ExecutorService}} might grow to several gigs [2]. By using
{{scheduleWithFixedDelay}} instead, we ensure that under pressure this leak
won't
happen. In order to mitigate the growth, a simple fix is proposed, simply
replacing {{scheduler.scheduleAtFixedRate}} by
{{scheduler.scheduleWithFixedDelay}}.
[1] it is single threaded and shared across all instances of
\{{MutableQuantiles}}:
[https://github.com/apache/hadoop/blob/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/metrics2/lib/MutableQuantiles.java#L66-L68]
[2] see attached mutable-quantiles-leak.
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