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https://issues.apache.org/jira/browse/HBASE-4528?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13121652#comment-13121652
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[email protected] commented on HBASE-4528:
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Two potential issues that I see:
#1 - If I'm reading it correctly, this change breaks current behavior for
tables where DEFERRED_LOG_FLUSH=true, where HLog.sync() should not be triggered.
#2 - It also seems like moving the memstore updates prior to the WAL append and
sync has the potential to leave around memstore entries that are not present in
the WAL if:
1) the log.sync() call throws an IOException
2) the memstore entries are made visible via the call to
rwcc.completeMemstoreInsert() in the finally block
3) the client sees the puts as failed due to the IOException
4) the subsequent roll of the HLog writer triggered by the IOException succeeds
-- the region server does not abort in this case.
In this case, wouldn't the client see the update as failed (due to the
IOException), while the memstore entries persist? So do the memstore changes
need to be tracked and rolled back? Or am I missing something?
/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
<https://reviews.apache.org/r/2141/#comment5460>
Doesn't this break current behavior in respect to tables with deferred log
flush set to "true"? Previously no sync was triggered for these tables.
Also, if the sync call throws an IOException that gets sent back to the
client, how do the memstore entries get cleared?
- Gary
On 2011-10-03 05:54:07, Dhruba Borthakur wrote:
bq.
bq. -----------------------------------------------------------
bq. This is an automatically generated e-mail. To reply, visit:
bq. https://reviews.apache.org/r/2141/
bq. -----------------------------------------------------------
bq.
bq. (Updated 2011-10-03 05:54:07)
bq.
bq.
bq. Review request for hbase.
bq.
bq.
bq. Summary
bq. -------
bq.
bq. The changes the multiPut operation so that the sync to the wal occurs
outside the rowlock.
bq.
bq. This enhancement is done only to HRegion.mut(Put[]) because this is the
only method that gets invoked from an application. The HRegion.put(Put) is used
only by unit tests and should possibly be deprecated.
bq.
bq. I have attached a unit test. I have not yet run all unit tests, but early
feedback on this patch will be very helpful.
bq.
bq.
bq. This addresses bug HBASE-4528.
bq. https://issues.apache.org/jira/browse/HBASE-4528
bq.
bq.
bq. Diffs
bq. -----
bq.
bq. /src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java 1178298
bq. /src/test/java/org/apache/hadoop/hbase/regionserver/TestParallelPut.java
PRE-CREATION
bq.
bq. Diff: https://reviews.apache.org/r/2141/diff
bq.
bq.
bq. Testing
bq. -------
bq.
bq. Not yet run the full suite of unit tests.
bq.
bq.
bq. Thanks,
bq.
bq. Dhruba
bq.
bq.
> The put operation can release the rowlock before sync-ing the Hlog
> ------------------------------------------------------------------
>
> Key: HBASE-4528
> URL: https://issues.apache.org/jira/browse/HBASE-4528
> Project: HBase
> Issue Type: Improvement
> Components: regionserver
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
> Attachments: appendNoSyncPut1.txt, appendNoSyncPut2.txt
>
>
> This allows for better throughput when there are hot rows. A single row
> update improves from 100 puts/sec/server to 5000 puts/sec/server.
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