Maysam Yabandeh created HADOOP-11301:
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Summary: [optionally] update jmx cache to drop old metrics
Key: HADOOP-11301
URL: https://issues.apache.org/jira/browse/HADOOP-11301
Project: Hadoop Common
Issue Type: Improvement
Reporter: Maysam Yabandeh
Assignee: Maysam Yabandeh
MetricsSourceAdapter::updateJmxCache() skips updating the info cache if no new
metric is added since last time:
{code}
int oldCacheSize = attrCache.size();
int newCacheSize = updateAttrCache();
if (oldCacheSize < newCacheSize) {
updateInfoCache();
}
{code}
This behavior is not desirable in some applications. For example nntop
(HDFS-6982) reports the top users via jmx. The list is updated after each
report. The previously reported top users hence should be removed from the
cache upon each report request.
In our production run of nntop we made a change to ignore the size check and
always perform updateInfoCache. I am planning to submit a patch including this
change. The feature can be enabled by a configuration parameter.
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