[jira] [Commented] (HBASE-14190) Assign hbase:namespace table ahead of user region assignment

["Ted Yu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-14190?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14660800#comment-14660800 ] 

Ted Yu commented on HBASE-14190:
--------------------------------

At start up, if column=info:server has value for hbase:namespace region, we can use retain assignment.
Otherwise we can randomly assign hbase:namespace region.

> Assign hbase:namespace table ahead of user region assignment
> ------------------------------------------------------------
>
>                 Key: HBASE-14190
>                 URL: https://issues.apache.org/jira/browse/HBASE-14190
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Ted Yu
>
> Currently the namespace table region is assigned like user regions.
> I spent several hours working with a customer where master couldn't finish initialization.
> Even though master was restarted quite a few times, it went down with the following:
> {code}
> 2015-08-05 17:16:57,530 FATAL [hdpmaster1:60000.activeMasterManager] master.HMaster: Master server abort: loaded coprocessors are: []
> 2015-08-05 17:16:57,530 FATAL [hdpmaster1:60000.activeMasterManager] master.HMaster: Unhandled exception. Starting shutdown.
> java.io.IOException: Timedout 300000ms waiting for namespace table to be assigned
>   at org.apache.hadoop.hbase.master.TableNamespaceManager.start(TableNamespaceManager.java:104)
>   at org.apache.hadoop.hbase.master.HMaster.initNamespace(HMaster.java:985)
>   at org.apache.hadoop.hbase.master.HMaster.finishActiveMasterInitialization(HMaster.java:779)
>   at org.apache.hadoop.hbase.master.HMaster.access$500(HMaster.java:182)
>   at org.apache.hadoop.hbase.master.HMaster$1.run(HMaster.java:1646)
>   at java.lang.Thread.run(Thread.java:744)
> {code}
> During previous run(s), namespace table was created, hence leaving an entry in hbase:meta.
> The following if block in TableNamespaceManager#start() was skipped:
> {code}
>     if (!MetaTableAccessor.tableExists(masterServices.getConnection(),
>       TableName.NAMESPACE_TABLE_NAME)) {
> {code}
> TableNamespaceManager#start() spins, waiting for namespace region to be assigned.
> There was issue in master assigning user regions.
> We tried issuing 'assign' command from hbase shell which didn't work because of the following check in MasterRpcServices#assignRegion():
> {code}
>       master.checkInitialized();
> {code}
> This scenario can be avoided if we assign hbase:namespace table after hbase:meta is assigned but before user table region assignment.



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