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https://issues.apache.org/jira/browse/HDFS-9381?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16149851#comment-16149851
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Hadoop QA commented on HDFS-9381:
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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}  0m  5s{color} 
| {color:red} HDFS-9381 does not apply to trunk. Rebase required? Wrong Branch? 
See https://wiki.apache.org/hadoop/HowToContribute for help. {color} |
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|| Subsystem || Report/Notes ||
| JIRA Issue | HDFS-9381 |
| JIRA Patch URL | 
https://issues.apache.org/jira/secure/attachment/12775199/HDFS-9381-04.patch |
| Console output | 
https://builds.apache.org/job/PreCommit-HDFS-Build/20952/console |
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> When same block came for replication for Striped mode, we can move that block 
> to PendingReplications
> ----------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-9381
>                 URL: https://issues.apache.org/jira/browse/HDFS-9381
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: erasure-coding, namenode
>    Affects Versions: 3.0.0-alpha1
>            Reporter: Uma Maheswara Rao G
>            Assignee: Uma Maheswara Rao G
>         Attachments: HDFS-9381.00.patch, HDFS-9381.01.patch, 
> HDFS-9381-02.patch, HDFS-9381-03.patch, HDFS-9381-04.patch
>
>
> Currently I noticed that we are just returning null if block already exists 
> in pendingReplications in replication flow for striped blocks.
> {code}
> if (block.isStriped()) {
>       if (pendingNum > 0) {
>         // Wait the previous recovery to finish.
>         return null;
>       }
> {code}
>  Here if we just return null and if neededReplications contains only fewer 
> blocks(basically by default if less than numliveNodes*2), then same blocks 
> can be picked again from neededReplications from next loop as we are not 
> removing element from neededReplications. Since this replication process need 
> to take fsnamesystmem lock and do, we may spend some time unnecessarily in 
> every loop. 
> So my suggestion/improvement is:
>  Instead of just returning null, how about incrementing pendingReplications 
> for this block and remove from neededReplications? and also another point to 
> consider here is, to add into pendingReplications, generally we need target 
> and it is nothing but to which node we issued replication command. Later when 
> after replication success and DN reported it, block will be removed from 
> pendingReplications from NN addBlock. 
>  So since this is newly picked block from neededReplications, we would not 
> have selected target yet. So which target to be passed to pendingReplications 
> if we add this block? One Option I am thinking is, how about just passing 
> srcNode itself as target for this special condition? So, anyway if the block 
> is really missed, srcNode will not report it. So this block will not be 
> removed from pending replications, so that when it is timed out, it will be 
> considered for replication again and that time it will find actual target to 
> replicate while processing as part of regular replication flow.



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