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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-19804) [hbase-indexer] Metrics source RegionServer,sub=Server already exists!
Date Tue, 23 Jan 2018 00:00:00 GMT

    [ https://issues.apache.org/jira/browse/HBASE-19804?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16335183#comment-16335183
] 

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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