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https://issues.apache.org/jira/browse/HBASE-24189?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17094198#comment-17094198
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Anoop Sam John commented on HBASE-24189:
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bq.For example, if region is split or merged and WAL isn't flushed prior to
opening child region and closing parent regions
I dont think so. For split or merge, the Region has to be closed 1st which
will flush the data. Splitting or merging of regions with out flushing memstore
is not possible. I did not check the code flow though.
> Regionserver recreates region folders in HDFS after replaying WAL with
> removed table entries
> --------------------------------------------------------------------------------------------
>
> Key: HBASE-24189
> URL: https://issues.apache.org/jira/browse/HBASE-24189
> Project: HBase
> Issue Type: Bug
> Components: regionserver, wal
> Affects Versions: 2.2.4
> Environment: * HDFS 3.1.3
> * HBase 2.1.4
> * OpenJDK 8
> Reporter: Andrey Elenskiy
> Assignee: Anoop Sam John
> Priority: Major
>
> Under the following scenario region directories in HDFS can be recreated with
> only recovered.edits in them:
> # Create table "test"
> # Put into "test"
> # Delete table "test"
> # Create table "test" again
> # Crash the regionserver to which the put has went to force the WAL replay
> # Region directory in old table is recreated in new table
> # hbase hbck returns inconsistency
> This appears to happen due to the fact that WALs are not cleaned up once a
> table is deleted and they still contain the edits from old table. I've tried
> wal_roll command on the regionserver before crashing it, but it doesn't seem
> to help as under some circumstances there are still WAL files around. The
> only solution that works consistently is to restart regionserver before
> creating the table at step 4 because that triggers log cleanup on startup:
> [https://github.com/apache/hbase/blob/f3ee9b8aa37dd30d34ff54cd39fb9b4b6d22e683/hbase-procedure/src/main/java/org/apache/hadoop/hbase/procedure2/store/wal/WALProcedureStore.java#L508|https://github.com/apache/hbase/blob/f3ee9b8aa37dd30d34ff54cd39fb9b4b6d22e683/hbase-procedure/src/main/java/org/apache/hadoop/hbase/procedure2/store/wal/WALProcedureStore.java#L508)]
>
> Truncating a table also would be a workaround by in our case it's a no-go as
> we create and delete tables in our tests which run back to back (create table
> in the beginning of the test and delete in the end of the test).
> A nice option in our case would be to provide hbase shell utility to force
> clean up of log files manually as I realize that it's not really viable to
> clean all of those up every time some table is removed.
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