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Date: Sun, 30 Jan 2011 13:59:44 -0500 (EST)
From: "Vijay (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
Subject: [jira] Commented: (CASSANDRA-1969) Use BB for row cache - To
 Improve GC performance.
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    [ https://issues.apache.org/jira/browse/CASSANDRA-1969?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12988632#action_12988632 ] 

Vijay commented on CASSANDRA-1969:
----------------------------------

Thanks Jonathan, This indeed looks cleaner than allocateDirect.... wasnt aware of jna.Memory earlier.... 

Regarding "and allocation is O(N)" --- It provides O(1) as it is backed by Queue and HashMap (which can have maximum of Integer.Max elements in HM) ... the idea was to reduce the number of operations while write..... With the assumption that the GC will cleanup the WeekReference immediately, and wont grow or fragment.... 

+1 for Jonathan's approach....

> Use BB for row cache - To Improve GC performance.
> -------------------------------------------------
>
>                 Key: CASSANDRA-1969
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1969
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>         Environment: Linux and Mac
>            Reporter: Vijay
>            Assignee: Vijay
>            Priority: Minor
>         Attachments: 0001-Config-1969.txt, 0001-introduce-ICache-InstrumentingCache-IRowCacheProvider.txt, 0002-implement-SerializingCache.txt, 0002-Update_existing-1965.txt, 0003-New_Cache_Providers-1969.txt, 0004-TestCase-1969.txt, BB_Cache-1945.png, JMX-Cache-1945.png, Old_Cahce-1945.png, POC-0001-Config-1945.txt, POC-0002-Update_existing-1945.txt, POC-0003-New_Cache_Providers-1945.txt
>
>
> Java BB.allocateDirect() will allocate native memory out of the JVM and will help reducing the GC pressure in the JVM with a large Cache.
> From some of the basic tests it shows around 50% improvement than doing a normal Object cache.
> In addition this patch provide the users an option to choose BB.allocateDirect or store everything in the heap.

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