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https://issues.apache.org/jira/browse/YARN-7320?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Robert Kanter reassigned YARN-7320:
-----------------------------------
Assignee: Misha Dmitriev
> Duplicate LiteralByteStrings in
> SystemCredentialsForAppsProto.credentialsForApp_
> --------------------------------------------------------------------------------
>
> Key: YARN-7320
> URL: https://issues.apache.org/jira/browse/YARN-7320
> Project: Hadoop YARN
> Issue Type: Improvement
> Reporter: Misha Dmitriev
> Assignee: Misha Dmitriev
>
> Using jxray (www.jxray.com) I've analyzed several heap dumps from YARN
> Resource Manager running in a big cluster. The tool uncovered several sources
> of memory waste. One problem, which results in wasting more than a quarter of
> all memory, is a large number of duplicate {{LiteralByteString}} objects
> coming from the following reference chain:
> {code}
> 1,011,810K (26.9%): byte[]: 5416705 / 100% dup arrays (22108 unique)
> ↖com.google.protobuf.LiteralByteString.bytes
> ↖org.apache.hadoop.yarn.proto.YarnServerCommonServiceProtos$.credentialsForApp_
> ↖{j.u.ArrayList}
> ↖j.u.Collections$UnmodifiableRandomAccessList.c
> ↖org.apache.hadoop.yarn.proto.YarnServerCommonServiceProtos$NodeHeartbeatResponseProto.systemCredentialsForApps_
> ↖org.apache.hadoop.yarn.server.api.protocolrecords.impl.pb.NodeHeartbeatResponsePBImpl.proto
> ↖org.apache.hadoop.yarn.server.resourcemanager.rmnode.RMNodeImpl.latestNodeHeartBeatResponse
> ↖org.apache.hadoop.yarn.server.resourcemanager.scheduler.fair.FSSchedulerNode.rmNode
> ...
> {code}
> That is, collectively reference chains that look as above hold in memory 5.4
> million {{LiteralByteString}} objects, but only ~22 thousand of these objects
> are unique. Deduplicating these objects, e.g. using a Google Object Interner
> instance, would save ~1GB of memory.
> It looks like the main place where the above {{LiteralByteString}}s are
> created and attached to the {{SystemCredentialsForAppsProto}} objects is in
> {{NodeHeartbeatResponsePBImpl.java}}, method
> {{addSystemCredentialsToProto()}}. Probably adding a call to an interner
> there will fix the problem. wi
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