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https://issues.apache.org/jira/browse/HBASE-26812?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17509088#comment-17509088
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Lars Hofhansl commented on HBASE-26812:
---------------------------------------

FYI... There's a problem with scanning too (I guess we knew). So PHOENIX-6501 
is also currently broken with HBase 2.
The savings from this are questionable anyway. Even on a local machine I see 
hardly a perf difference with disabling this.

I'd vote for ripping it out.

> ShortCircuitingClusterConnection fails to close RegionScanners when making 
> short-circuited calls
> ------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-26812
>                 URL: https://issues.apache.org/jira/browse/HBASE-26812
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 2.4.9
>            Reporter: Lars Hofhansl
>            Priority: Critical
>
> Just ran into this on the Phoenix side.
> We retrieve a Connection via 
> {{{}RegionCoprocessorEnvironment.createConnection... getTable(...){}}}. And 
> then call get on that table. The Get's key happens to be local. Now each call 
> to table.get() leaves an open StoreScanner around forever. (verified with a 
> memory profiler).
> There references are held via 
> RegionScannerImpl.storeHeap.scannersForDelayedClose. Eventially the 
> RegionServer goes into a GC of death and can only ended with kill -9.
> The reason appears to be that in this case there is no currentCall context. 
> Some time in 2.x the Rpc handler/call was made responsible for closing open 
> region scanners, but we forgot to handle {{ShortCircuitingClusterConnection}}
> It's not immediately clear how to fix this. But it does make 
> ShortCircuitingClusterConnection useless and dangerous. If you use it, you 
> *will* create a giant memory leak.



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