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From "Vijay (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (CASSANDRA-7030) Remove JEMallocAllocator
Date Mon, 14 Apr 2014 21:18:16 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-7030?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13968847#comment-13968847
] 

Vijay edited comment on CASSANDRA-7030 at 4/14/14 9:17 PM:
-----------------------------------------------------------

JEMalloc will be better if you have different sized objects (if of same size then there isn't
much fragmentation), the benchmark in the other ticket uses "50000 2000000" which will provide
you a distribution which can be compared... I don't think the test you are proposing is in
the same lines... 

Anyways i don't really have any bias on this ticket as we don't use this in production and
thinking on JNI alternatives for Serialized cache anyways...



was (Author: vijay2win@yahoo.com):
JEMalloc will be better if you have different sized objects (if of same size then there isn't
much fragmentation), the benchmark in the other ticket uses "50000 2000000" which will provide
you a distribution which can be compared... I don't think the test you are proposing is valid...


Anyways i don't really have any bias on this ticket as we don't use this in production and
thinking on JNI alternatives for Serialized cache anyways...


> Remove JEMallocAllocator
> ------------------------
>
>                 Key: CASSANDRA-7030
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7030
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Benedict
>            Assignee: Benedict
>            Priority: Minor
>              Labels: performance
>             Fix For: 2.1 beta2
>
>         Attachments: 7030.txt
>
>
> JEMalloc, whilst having some nice performance properties by comparison to Doug Lea's
standard malloc algorithm in principle, is pointless in practice because of the JNA cost.
In general it is around 30x more expensive to call than unsafe.allocate(); malloc does not
have a variability of response time as extreme as the JNA overhead, so using JEMalloc in Cassandra
is never a sensible idea. I doubt if custom JNI would make it worthwhile either.
> I propose removing it.



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