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From "Ted Yu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-14190) Assign system tables ahead of user region assignment
Date Mon, 10 Aug 2015 22:47:46 GMT

    [ https://issues.apache.org/jira/browse/HBASE-14190?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14680898#comment-14680898
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Ted Yu commented on HBASE-14190:
--------------------------------

bq. add additional tables to the 'hbase:' namespace with the expectation they are system tables
that should be deployed ahead of user tables?

To my knowledge, there is currently no static registry of system tables. Patch v7 adds MetaTableAccessor#getSystemTableRegionsAndLocations()
which scans hbase:meta table for system tables.

However, on fresh start, this method would not work.

Comment is welcome.

> Assign system tables 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
>            Assignee: Ted Yu
>            Priority: Critical
>         Attachments: 14190-v5.txt, 14190-v6.txt, 14190-v7.txt
>
>
> 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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