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https://issues.apache.org/jira/browse/HBASE-2231?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12835290#action_12835290
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Karthik Ranganathan commented on HBASE-2231:
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Just wanted to attach evidence to the issue pointed out by Todd - "the
regionserver also rolls its HLog right after the pause. In this case, the
master might not catch the rolled HLog file, and the RS wouldn't be properly
interrupted"
>From an email exchange between a few of us:
> Look at these snippets from the log:
> 2010-02-15 16:23:56,493 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer: Got ZooKeeper event,
> state: Disconnected, type: None, path: null
> 2010-02-15 16:23:57,848 WARN org.apache.hadoop.hbase.regionserver.HLog: IPC
> Server handler 30 on 60020 took 1200ms appending an edit to hlog;
> editcount=121
> 2010-02-15 16:24:04,697 INFO
> org.apache.hadoop.hbase.regionserver.HRegionServer: Got ZooKeeper event,
> state: Expired, type: None, path: null
> 2010-02-15 16:24:04,697 WARN org.apache.zookeeper.ClientCnxn: Exception
> closing session 0x326c5173bc80000 to sun.nio.ch.selectionkeyi...@5534afcb
>
> This means master did not take possession of the latest hlog. So the RS
> actually appended into the log AFTER the zk timeout happened. The suggestion
> from yesterday's discussion (first open the last hlog) should take care of
> this edit.
> Compaction events should be written to HLog
> -------------------------------------------
>
> Key: HBASE-2231
> URL: https://issues.apache.org/jira/browse/HBASE-2231
> Project: Hadoop HBase
> Issue Type: Improvement
> Components: regionserver
> Reporter: Todd Lipcon
>
> The sequence for a compaction should look like this:
> # Compact region to "new" files
> # Write a "Compacted Region" entry to the HLog
> # Delete "old" files
> This deals with a case where the RS has paused between step 1 and 2 and the
> regions have since been reassigned.
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