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https://issues.apache.org/jira/browse/HBASE-1121?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12665626#action_12665626
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Jim Kellerman commented on HBASE-1121:
--------------------------------------
The reason for this is that the root region needs to be set before any HTable
accesses are
done. It is never reset, because it is assumed that HTable/HConnectionManager
will detect if
the root region has moved and recalibrate accordingly. During the startup
process, an HTable
in a server process will never start because it cannot find the root or meta
regions (because
it is trying to serve the root or meta regions). It is a total hack to work
around the fact
that HTable/HConnectionManager do not work in server processes, especially
during safe-mode.
This is why I have advocated in the past for never using HTable in server
processes. The only
reason we have done so, is that doing HRegionServer RPC's for similar HTable
requests are a
whole lot more complicated, and would require a duplication of code (or a
significant
refactoring - I am opposed to duplication of code, but the refactoring is not
going to be
trivial - in fact, I see it as being very difficult)
> Cluster confused about where -ROOT- is
> --------------------------------------
>
> Key: HBASE-1121
> URL: https://issues.apache.org/jira/browse/HBASE-1121
> Project: Hadoop HBase
> Issue Type: Bug
> Environment: TRUNK trying to do big upload
> Reporter: stack
> Assignee: Jim Kellerman
> Attachments: 1121.patch
>
>
> Each node in cluster is doing below:
> {code}
> 2009-01-11 20:52:22,739 [regionserver/0:0:0:0:0:0:0:0:60020.compactor] DEBUG
> org.apache.hadoop.hbase.client.HConnectionManager$TableServers: Attempt 0 of
> 10 failed with <org.apache.hadoop.hbase.NotServingRegionException:
> org.apache.hadoop.hbase.NotServingRegionException: -ROOT-,,0
> at
> org.apache.hadoop.hbase.regionserver.HRegionServer.getRegion(HRegionServer.java:2064)
> at
> org.apache.hadoop.hbase.regionserver.HRegionServer.getClosestRowBefore(HRegionServer.java:1545)
> at sun.reflect.GeneratedMethodAccessor17.invoke(Unknown Source)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> at java.lang.reflect.Method.invoke(Method.java:597)
> at org.apache.hadoop.hbase.ipc.HBaseRPC$Server.call(HBaseRPC.java:632)
> at
> org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:894)
> >. Retrying after sleep of 20002009-01-11 20:52:22,742
> >[regionserver/0:0:0:0:0:0:0:0:60020.compactor] DEBUG
> >org.apache.hadoop.hbase.client.HConnectionManager$TableServers: Found ROOT
> >REGION => {NAME => '-ROOT-,,0', STARTKEY => '', ENDKEY => '', ENCODED =>
> >70236052, TABLE => {{NAME => '-ROOT-', IS_ROOT => 'true', IS_META => 'true',
> >FAMILIES => [{NAME => 'info', BLOOMFILTER => 'false', COMPRESSION => 'NONE',
> >VERSIONS => '10', LENGTH => '2147483647', TTL => '-1', IN_MEMORY => 'false',
> >BLOCKCACHE => 'true'}], INDEXES => []}}2009-01-11 20:52:24,759
> >[regionserver/0:0:0:0:0:0:0:0:60020.compactor] DEBUG
> >org.apache.hadoop.hbase.client.HConnectionManager$TableServers: Attempt 1 of
> >10 failed with <org.apache.hadoop.hbase.NotServingRegionException:
> >org.apache.hadoop.hbase.NotServingRegionException: -ROOT-,,0
> at
> org.apache.hadoop.hbase.regionserver.HRegionServer.getRegion(HRegionServer.java:2064)
> at
> org.apache.hadoop.hbase.regionserver.HRegionServer.getClosestRowBefore(HRegionServer.java:1545)
> at sun.reflect.GeneratedMethodAccessor17.invoke(Unknown Source)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> at java.lang.reflect.Method.invoke(Method.java:597)
> at org.apache.hadoop.hbase.ipc.HBaseRPC$Server.call(HBaseRPC.java:632)
> at
> org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:894)
> {code}
> I tried to close the root region and tripped over hbase-1120.
> So I killed the regionserver hosting -ROOT- but weirdly had no effect as
> though the regionservers' internal cache of -ROOT- location cannot be
> changed.
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