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https://issues.apache.org/jira/browse/HBASE-14004?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16167437#comment-16167437
 ] 

Hadoop QA commented on HBASE-14004:
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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | {color:blue} reexec {color} | {color:blue}  0m  
0s{color} | {color:blue} Docker mode activated. {color} |
| {color:red}-1{color} | {color:red} patch {color} | {color:red}  2m 47s{color} 
| {color:red} HBASE-14004 does not apply to master. Rebase required? Wrong 
Branch? See https://yetus.apache.org/documentation/0.4.0/precommit-patchnames 
for help. {color} |
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|| Subsystem || Report/Notes ||
| JIRA Issue | HBASE-14004 |
| JIRA Patch URL | 
https://issues.apache.org/jira/secure/attachment/12887272/HBASE-14004-v2.patch |
| Console output | 
https://builds.apache.org/job/PreCommit-HBASE-Build/8641/console |
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This message was automatically generated.



> [Replication] Inconsistency between Memstore and WAL may result in data in 
> remote cluster that is not in the origin
> -------------------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-14004
>                 URL: https://issues.apache.org/jira/browse/HBASE-14004
>             Project: HBase
>          Issue Type: Bug
>          Components: regionserver, Replication
>            Reporter: He Liangliang
>            Assignee: Duo Zhang
>            Priority: Critical
>              Labels: replication, wal
>             Fix For: 3.0.0, 2.0.0-alpha-4
>
>         Attachments: HBASE-14004.patch, HBASE-14004-v1.patch, 
> HBASE-14004-v2.patch, HBASE-14004-v2.patch
>
>
> Looks like the current write path can cause inconsistency between 
> memstore/hfile and WAL which cause the slave cluster has more data than the 
> master cluster.
> The simplified write path looks like:
> 1. insert record into Memstore
> 2. write record to WAL
> 3. sync WAL
> 4. rollback Memstore if 3 fails
> It's possible that the HDFS sync RPC call fails, but the data is already  
> (may partially) transported to the DNs which finally get persisted. As a 
> result, the handler will rollback the Memstore and the later flushed HFile 
> will also skip this record.
> ==================================
> This is a long lived issue. The above problem is solved by write path 
> reorder, as now we will sync wal first before modifying memstore. But the 
> problem may still exists as replication thread may read the new data before 
> we return from hflush. See this document for more details:
> https://docs.google.com/document/d/11AyWtGhItQs6vsLRIx32PwTxmBY3libXwGXI25obVEY/edit#
> So we need to keep a sync length in WAL and tell replication wal reader this 
> is limit when you read this wal file.



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