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From "Yuan Kang (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-4888) Not close ResultScanner cause the cluster abnormal ( RS memory increase)
Date Wed, 30 Nov 2011 02:17:43 GMT

    [ https://issues.apache.org/jira/browse/HBASE-4888?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13159750#comment-13159750
] 

Yuan Kang commented on HBASE-4888:
----------------------------------

I came into this issus in online system and find some reference in 《HBase: The Definitive
Guide》. 

It writes  "Scanner Leases
Make sure you release a scanner instance as timely as possible. An open scanner holds quite
a few resources on the server side, which could accumulate to a large amount of heap space
occupied. When you are done with the current scan call close(), and consider adding this into
a try/finally construct to ensure it is called, even if there are exceptions or errors during
the iterations.

Like row locks, scanners are protected against stray clients blocking resources for too long,
using the same lease based mechanisms. You need to set the same configuration property to
modify the timeout threshold (in milliseconds):
<property>
<name>hbase.regionserver.lease.period</name>
<value>120000</value>
</property>
You need to make sure that the property is set to an appropriate value that make sense for
locks and the scanner leases.
"

But I find 'hbase.regionserver.lease.period' don't work well and Our RS hold high memory for
a much longer time more than 'hbase.regionserver.lease.period' .After I add 'rs.close()' in
my code,it disappeared



                
> Not close ResultScanner cause the cluster abnormal ( RS memory increase)
> ------------------------------------------------------------------------
>
>                 Key: HBASE-4888
>                 URL: https://issues.apache.org/jira/browse/HBASE-4888
>             Project: HBase
>          Issue Type: Bug
>          Components: client
>    Affects Versions: 0.90.3
>         Environment: CentOS 5.5 final, hadoop-0.20.2-cdh3u1,hbase-0.20.2-cdh3u1
>            Reporter: Yuan Kang
>              Labels: ResultScanner
>   Original Estimate: 672h
>  Remaining Estimate: 672h
>
> A ResultScanner is created in client side, If the user doesn't invoke the "ResultScanner.close()"
,it happens that the memory of RegionServer increase rapidly and hold for a long time. Finally,the
cluster goes to an abnormal status
>  

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