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https://issues.apache.org/jira/browse/HBASE-8505?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13652355#comment-13652355
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Enis Soztutar commented on HBASE-8505:
--------------------------------------
That log entry is still valid, because we still delete the region from meta
because daughters do not hold references. The difference is that we do not do
two separate deletes.
> References to split daughters should not be deleted separately from parent
> META entry
> -------------------------------------------------------------------------------------
>
> Key: HBASE-8505
> URL: https://issues.apache.org/jira/browse/HBASE-8505
> Project: HBase
> Issue Type: Bug
> Components: regionserver
> Reporter: Enis Soztutar
> Assignee: Enis Soztutar
> Fix For: 0.98.0, 0.94.8, 0.95.1
>
> Attachments: hbase-8505_v1-0.94.patch
>
>
> In CatalogJanitor, we clean up the parent regions whose daughters does not
> have any more references to their parent regions. In doing so, we do two
> Delete's one for removing the split daughter columns, and the other for
> removing the row.
> The first one seems unnecessary, and causes NPE from concurrent MetaScanner.
> Stack trace:
> {code}
> 2013-05-07 04:49:40,828|machine|INFO|Exception in thread "main"
> java.lang.NullPointerException
> 2013-05-07 04:49:40,828|machine|INFO|at
> org.apache.hadoop.hbase.util.Writables.getWritable(Writables.java:103)
> 2013-05-07 04:49:40,828|machine|INFO|at
> org.apache.hadoop.hbase.util.Writables.getHRegionInfo(Writables.java:147)
> 2013-05-07 04:49:40,829|machine|INFO|at
> org.apache.hadoop.hbase.client.MetaScanner$BlockingMetaScannerVisitor.processRow(MetaScanner.java:406)
> 2013-05-07 04:49:40,829|machine|INFO|at
> org.apache.hadoop.hbase.client.MetaScanner$TableMetaScannerVisitor.processRow(MetaScanner.java:487)
> 2013-05-07 04:49:40,830|machine|INFO|at
> org.apache.hadoop.hbase.client.MetaScanner.metaScan(MetaScanner.java:224)
> 2013-05-07 04:49:40,830|machine|INFO|at
> org.apache.hadoop.hbase.client.MetaScanner.access$000(MetaScanner.java:54)
> 2013-05-07 04:49:40,830|machine|INFO|at
> org.apache.hadoop.hbase.client.MetaScanner$1.connect(MetaScanner.java:133)
> 2013-05-07 04:49:40,831|machine|INFO|at
> org.apache.hadoop.hbase.client.MetaScanner$1.connect(MetaScanner.java:130)
> 2013-05-07 04:49:40,831|machine|INFO|at
> org.apache.hadoop.hbase.client.HConnectionManager.execute(HConnectionManager.java:384)
> 2013-05-07 04:49:40,831|machine|INFO|at
> org.apache.hadoop.hbase.client.MetaScanner.metaScan(MetaScanner.java:130)
> 2013-05-07 04:49:40,832|machine|INFO|at
> org.apache.hadoop.hbase.client.MetaScanner.metaScan(MetaScanner.java:105)
> 2013-05-07 04:49:40,832|machine|INFO|at
> org.apache.hadoop.hbase.client.MetaScanner.metaScan(MetaScanner.java:83)
> 2013-05-07 04:49:40,832|machine|INFO|at
> org.apache.hadoop.hbase.client.MetaScanner.allTableRegions(MetaScanner.java:323)
> 2013-05-07 04:49:40,833|machine|INFO|at
> org.apache.hadoop.hbase.client.HTable.getRegionLocations(HTable.java:485)
> 2013-05-07 04:49:40,833|machine|INFO|at
> org.apache.hadoop.hbase.client.HTable.getStartEndKeys(HTable.java:438)
> {code}
> Master is doing the CatalogJanitor concurrently:
> {code}
> 2013-05-07 04:49:40,636 INFO org.apache.hadoop.hbase.catalog.MetaEditor:
> Deleted daughters references, qualifier=splitA and qualifier=splitB, from
> parent
> IntegrationTestBigLinkedList,\x07\xFB\x98\xB7a\x89\xF5\xE6,1367898577620.4ef1329ff0e8911db998ac8ccd32108d.
> 2013-05-07 04:49:40,666 INFO org.apache.hadoop.hbase.catalog.MetaEditor:
> Deleted region
> IntegrationTestBigLinkedList,\x07\xFB\x98\xB7a\x89\xF5\xE6,1367898577620.4ef1329ff0e8911db998ac8ccd32108d.
> from META
> 2013-05-07 04:49:40,690 INFO org.apache.hadoop.hbase.catalog.MetaEditor:
> Deleted daughters references, qualifier=splitA and qualifier=splitB, from
> parent
> IntegrationTestBigLinkedList,\x0B\xF8n\xEA\xD3\xAA\xA9\x92,1367898577620.b502376df2623cb0be3f0c1664d799a6.
> 2013-05-07 04:49:40,716 INFO org.apache.hadoop.hbase.catalog.MetaEditor:
> Deleted region
> IntegrationTestBigLinkedList,\x0B\xF8n\xEA\xD3\xAA\xA9\x92,1367898577620.b502376df2623cb0be3f0c1664d799a6.
> from META
> 2013-05-07 04:49:40,742 INFO org.apache.hadoop.hbase.catalog.MetaEditor:
> Deleted daughters references, qualifier=splitA and qualifier=splitB, from
> parent
> IntegrationTestBigLinkedList,\x17\xF5\x11\xB9\xE3\xDB)\x0C,1367898541729.ec2df58fafb823cec6e793ba35e2241d.
> {code}
> This is critical for 0.94, but not for 0.95 and trunk due to HBASE-7721.
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