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https://issues.apache.org/jira/browse/HBASE-6254?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13398735#comment-13398735
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Zhihong Ted Yu commented on HBASE-6254:
---------------------------------------

Since KeyValue implements HeapSize, we can keep adding column qualifiers until 
we reach configurable threshold.
After get(get, false) returns, we can parse out the column qualifiers from 
result.
                
> deletes w/ many column qualifiers overwhelm Region Server
> ---------------------------------------------------------
>
>                 Key: HBASE-6254
>                 URL: https://issues.apache.org/jira/browse/HBASE-6254
>             Project: HBase
>          Issue Type: Bug
>          Components: performance, regionserver
>    Affects Versions: 0.94.0
>         Environment: 5 node Cent OS + 1 master, v0.94 on cdh3u3
>            Reporter: Ted Tuttle
>
> Execution of Deletes constructed with thousands of calls to 
> Delete.deleteColumn(family, qualifier) are very expensive and slow.
> On our (quiet) cluster, a Delete w/ 20k qualifiers took about 13s to complete 
> (as measured by client).
> When 10 such Deletes were sent to the cluster via 
> HTable.delete(List<Delete>), one of RegionServers ended up w/ 5 of the 
> requests and became 100% CPU utilized for about 1 hour.
> This lead to the client timing out after 20min (2min x 10 retries).  In one 
> case, the client was able to fill the RPC callqueue and received the 
> following error:
> {code}
>   Failed all from region=<region>,hostname=<host>, port=<port> 
> java.util.concurrent.ExecutionException: java.io.IOException: Call queue is 
> full, is ipc.server.max.callqueue.size too small?
> {code}
> Based on feedback (http://search-hadoop.com/m/yITsc1WcDWP), I switched to 
> Delete.deleteColumn(family, qual, timestamp) where timestamp came from 
> KeyValue retrieved from scan based on domain objects.  This version of the 
> delete ran in about 500ms.
> User group thread titled "RS unresponsive after series of deletes" has 
> related logs and stacktraces.  
> Link to thread: http://search-hadoop.com/m/RmIyr1WcDWP
> Here is the stack dump of region server: http://pastebin.com/8y5x4xU7

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