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https://issues.apache.org/jira/browse/AMBARI-18694?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Xiaobing Zhou updated AMBARI-18694:
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Summary: Add JVM settings of forcing garbage collections to release
DataNode heap (was: Add JVM settings of forcing garbage collections to
alleviate heap consumption on DataNode)
> Add JVM settings of forcing garbage collections to release DataNode heap
> ------------------------------------------------------------------------
>
> Key: AMBARI-18694
> URL: https://issues.apache.org/jira/browse/AMBARI-18694
> Project: Ambari
> Issue Type: Improvement
> Reporter: Xiaobing Zhou
>
> As HDFS-11047 reported, DirectoryScanner does scan by deep copying
> FinalizedReplica. In a deployment with 500,000+ blocks, we've seen the DN
> heap usage being accumulated to high peaks very quickly. Deep copies of
> FinalizedReplica will make DN heap usage even worse if directory scans are
> scheduled more frequently.
> Another factor is that huge number of ScanInfo instances corresponding to
> HDFS blocks are lingering in garbage to eat many heap memories until a full
> GC takes place.
> This proposes adding JVM settings to force GC more frequently to release
> DataNode heap consumed as a result of two aforementioned reasons, i.e. add
> the options to HADOOP_DATANODE_OPTS
> {noformat}
> -XX:CMSInitiatingOccupancyFraction=70 -XX:+UseCMSInitiatingOccupancyOnly
> -XX:ConcGCThreads=8 -XX:+UseConcMarkSweepGC
> {noformat}
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