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Date: Sat, 17 Nov 2012 13:05:22 +0000 (UTC)
From: "Jonathan Ellis (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
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Subject: [jira] [Commented] (CASSANDRA-3997) Make SerializingCache Memory
 Pluggable
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    [ https://issues.apache.org/jira/browse/CASSANDRA-3997?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13499414#comment-13499414 ] 

Jonathan Ellis commented on CASSANDRA-3997:
-------------------------------------------

So to summarize:

- We don't need JNI
- LD_PRELOAD makes things segfault but LD_LIBRARY_PATH works fine

Right?

It looks to me like we can make Allocator just return a long.  Then the Memory heirarchy doesn't need to change at all.

Messier but easy: just add a static Allocator to Memory.

More refactoring but cleaner? move allocation outside of Memory and replace with constructor (long reference, long bytes); add allocate(long bytes) and allocateRefCounted(long bytes) factory to Allocator.  RefCountedMemory would need to wrap Memory instead of subclassing.

I also suggest adding a commented-out example to cassandra.yaml and cassandra-env.sh to illustrate how to enable this for those brave enough to try it.  (This will go into 1.3 so plenty of time to test.)
                
> Make SerializingCache Memory Pluggable
> --------------------------------------
>
>                 Key: CASSANDRA-3997
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3997
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Vijay
>            Assignee: Vijay
>            Priority: Minor
>              Labels: cache
>             Fix For: 1.3
>
>         Attachments: 0001-CASSANDRA-3997.patch, 0001-CASSANDRA-3997-v2.patch, 0001-CASSANDRA-3997-v3.patch, jna.zip
>
>
> Serializing cache uses native malloc and free by making FM pluggable, users will have a choice of gcc malloc, TCMalloc or JEMalloc as needed. 
> Initial tests shows less fragmentation in JEMalloc but the only issue with it is that (both TCMalloc and JEMalloc) are kind of single threaded (at-least they crash in my test otherwise).

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