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https://issues.apache.org/jira/browse/HBASE-4497?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13116160#comment-13116160
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ramkrishna.s.vasudevan commented on HBASE-4497:
-----------------------------------------------

I am not aware of ZK much.
Your 3rd point looks good to me Ming.
I think HBASE-4015 may handle the race you have told above.
{code}
      if (hijack && null != curDataInZNode) {
        EventType eventType = curDataInZNode.getEventType();
        if (eventType.equals(EventType.RS_ZK_REGION_CLOSING)
            || eventType.equals(EventType.RS_ZK_REGION_CLOSED)
            || eventType.equals(EventType.RS_ZK_REGION_OPENED)) {
          return -1;
        }
{code}
Also if the timeout succeeds the transiting from OPENING to OPENED will fail in 
RS.
May be there may be an entry in META with the old RS.

                
> If region opening fails after updating META HBCK reports it as inconsistent 
> and scanning the region throws NSRE
> ---------------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-4497
>                 URL: https://issues.apache.org/jira/browse/HBASE-4497
>             Project: HBase
>          Issue Type: Bug
>            Reporter: ramkrishna.s.vasudevan
>            Priority: Critical
>
> As per the discussion in the mail chain "HBCK reporting of possible mismatch 
> in RS assignment" this JIRA is created.
> Consider two RS-> RS1 and RS2.
> A region tries to open in RS1. But it takes a while.  The RS1 has still not 
> updated meta and transitioned the node from OPENING to OPENED
> So timeout assigns the region to RS2.  RS2 successfully updates the META and 
> opens the region.
> Now RS1 tries to act on the region by first updating the META and then 
> transiting the node to OPENING to OPENED.
> RS1 transiting the node to OPENING to OPENED will fail.  But the META entry 
> will have RS1 as the latest.
> Now HBCK reports this as an inconsistency and if we try to scan the Region we 
> get NotServingRegionException.

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