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Posted to issues@hbase.apache.org by "Huaxiang Sun (Jira)" <ji...@apache.org> on 2020/05/14 05:28:00 UTC

[jira] [Created] (HBASE-24370) Avoid aggressive MergeRegion and GCMultipleMergedRegionsProcedure

Huaxiang Sun created HBASE-24370:
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             Summary: Avoid aggressive MergeRegion and GCMultipleMergedRegionsProcedure 
                 Key: HBASE-24370
                 URL: https://issues.apache.org/jira/browse/HBASE-24370
             Project: HBase
          Issue Type: Bug
          Components: master
            Reporter: Huaxiang Sun
            Assignee: Huaxiang Sun


In [https://github.com/apache/hbase/blob/a40a0322a73add68d9cb0579abacdd6a2e41e8fb/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/MergeTableRegionsProcedure.java#L478,  |https://github.com/apache/hbase/blob/a40a0322a73add68d9cb0579abacdd6a2e41e8fb/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/MergeTableRegionsProcedure.java#L478]

prepareMergeRegion, it checks if one of merged parent regions is a merged child region and has not been GCed. If it is ready to GC, it will kick off a GCMultipleMergedRegionsProcedure and also start the MergeRegionProcedure. There is a race condition here. If MergeRegionProcedure finishes first, it will delete meta row for the merged child region. Then GCMultipleMergedRegionsProcedure runs, and because the newly added check, it thinks GC has been done and wont schedule GCRegionProcedure to clean up those merged parent regions. The end result is that these merged parent regions are left as orphans on Filesystem.

 

[https://github.com/apache/hbase/blob/a40a0322a73add68d9cb0579abacdd6a2e41e8fb/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/GCMultipleMergedRegionsProcedure.java#L105]

 

The proposed solution is to avoid being so aggressive, if it needs to kick off GCMultipleMergedRegionsProcedure, then abort MergeRegionProcedure and user can try MergeRegionProcedure later.

[|https://github.com/apache/hbase/blob/a40a0322a73add68d9cb0579abacdd6a2e41e8fb/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/MergeTableRegionsProcedure.java#L478]

 

 



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