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https://issues.apache.org/jira/browse/HBASE-19804?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16335183#comment-16335183
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stack commented on HBASE-19804:
-------------------------------
Punting from beta-2 since a workaround. We register a bunch of mbeans when we
come up. We'd have to add sub=PORT_NO to all beans so you could register
multiple RegionServers in same context.
> [hbase-indexer] Metrics source RegionServer,sub=Server already exists!
> ----------------------------------------------------------------------
>
> Key: HBASE-19804
> URL: https://issues.apache.org/jira/browse/HBASE-19804
> Project: HBase
> Issue Type: Improvement
> Components: hbase-indexer
> Affects Versions: 2.0.0-beta-1
> Reporter: stack
> Assignee: stack
> Priority: Major
> Fix For: 2.0.0
>
>
> In the past, the hbase-indexer runs multiple RegionServers per JVM. In old
> days, they had their own cut-down "RegionServer". In 2.0.0, we made it so
> they could run an actual RegionServer but with services disabled. The latter
> has an issue if you run more than one instance per JVM and it is NOT a
> minihbasecluster instance. It fails with:
> {code:java}
> 1:09:13.371 PM ERROR HRegionServer
> Failed init
> org.apache.hadoop.metrics2.MetricsException: Metrics source
> RegionServer,sub=Server already exists!
> at
> org.apache.hadoop.metrics2.lib.DefaultMetricsSystem.newSourceName(DefaultMetricsSystem.java:152)
> at
> org.apache.hadoop.metrics2.lib.DefaultMetricsSystem.sourceName(DefaultMetricsSystem.java:125)
> at
> org.apache.hadoop.metrics2.impl.MetricsSystemImpl.register(MetricsSystemImpl.java:229)
> at
> org.apache.hadoop.hbase.metrics.BaseSourceImpl.<init>(BaseSourceImpl.java:115)
> at
> org.apache.hadoop.hbase.regionserver.MetricsRegionServerSourceImpl.<init>(MetricsRegionServerSourceImpl.java:101)
> at
> org.apache.hadoop.hbase.regionserver.MetricsRegionServerSourceImpl.<init>(MetricsRegionServerSourceImpl.java:93)
> at
> org.apache.hadoop.hbase.regionserver.MetricsRegionServerSourceFactoryImpl.createServer(MetricsRegionServerSourceFactoryImpl.java:69)
> at
> org.apache.hadoop.hbase.regionserver.MetricsRegionServer.<init>(MetricsRegionServer.java:56)
> at
> org.apache.hadoop.hbase.regionserver.HRegionServer.handleReportForDutyResponse(HRegionServer.java:1519)
> at
> org.apache.hadoop.hbase.regionserver.HRegionServer.run(HRegionServer.java:954)
> at com.ngdata.sep.impl.SepConsumer$1.run(SepConsumer.java:203){code}
>
> If you look in [10:26 AM] Wolfgang Hoschek: DefaultMetricsSystem code (found
> by [~whoschek]), you'll see this:
> {code:java}
> synchronized ObjectName newObjectName(String name) {
> try {
> if (mBeanNames.map.containsKey(name) && !miniClusterMode) {
> throw new MetricsException(name +" already exists!");
> }
> return new ObjectName(mBeanNames.uniqueName(name));
> } catch (Exception e) {
> throw new MetricsException(e);
> }
> }{code}
> i.e. if we are in a mini cluster context, we will not fail registering the
> second bean instance.
>
> If you look in master startup in HMasterCommandLine, you will see:
>
> {code:java}
> // If 'local', defer to LocalHBaseCluster instance. Starts master
> // and regionserver both in the one JVM.
> if (LocalHBaseCluster.isLocal(conf)) {
> DefaultMetricsSystem.setMiniClusterMode(true);
> ....{code}
> ... will ensure we don't get the above exception in minihbasecluster context.
>
> So, the idea here is to make it so being able to run more than one RS per JVM
> is cleaner than doing the above hack. It needs to be a config too.... a
> config. which says don't fail startup if second mbean registration just
> because two RS in the one context (A later issue will be the accounting of
> metrics per RS... If more than one RS, then we should make a unique mbean per
> RS in the JVM).
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