[jira] [Commented] (HBASE-16931) Setting cell's seqId to zero in compaction flow might cause RS down.

["Anoop Sam John (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-16931?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15601057#comment-15601057 ] 

Anoop Sam John commented on HBASE-16931:
----------------------------------------

I just changed the subject of the jira and upped the priority to critical as this will be a very bad bug when occurs. Chance of this to occur may be rare. Still !!!

> Setting cell's seqId to zero in compaction flow might cause RS down.
> --------------------------------------------------------------------
>
>                 Key: HBASE-16931
>                 URL: https://issues.apache.org/jira/browse/HBASE-16931
>             Project: HBase
>          Issue Type: Bug
>          Components: regionserver
>    Affects Versions: 2.0.0
>            Reporter: binlijin
>            Assignee: binlijin
>            Priority: Critical
>         Attachments: HBASE-16931-master.patch
>
>
> Compactor#performCompaction
>       do {
>         hasMore = scanner.next(cells, scannerContext);
>         // output to writer:
>         for (Cell c : cells) {
>           if (cleanSeqId && c.getSequenceId() <= smallestReadPoint) {
>             CellUtil.setSequenceId(c, 0);
>           }
>           writer.append(c);
>         }
>         cells.clear();
>       } while (hasMore);
> scanner.next will choose at most "hbase.hstore.compaction.kv.max" kvs, the last cell still reference by StoreScanner.prevCell, so if cleanSeqId is called when the scanner.next call StoreScanner.checkScanOrder may throw exception and cause regionserver down.



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