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https://issues.apache.org/jira/browse/CASSANDRA-6126?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14087238#comment-14087238
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graham sanderson edited comment on CASSANDRA-6126 at 8/6/14 4:43 AM:
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I don't seem to be able to re-open this, but we just noticed when checking
cassandra-env.sh diffs during upgrade (we already have MALLOC_ARENA_MAX=4 as
our own change)
In the patch in the 2.0 codebase for this issue {{MALLOC_ARENA_MAX}} is not
{{EXPORTed}}
was (Author: graham sanderson):
I don't seem to be able to re-open this, but we just noticed when checking
cassandra-env.sh diffs during upgrade (we already have MALLOC_ARENA_MAX=4 as
our own change)
In the patch in the 2.0 codebase for this issue {{MALLOC_ARENA_MAX}} is not
{{EXPORT}}ed
> Set MALLOC_ARENA_MAX in cassandra-env.sh for new glibc per-thread allocator
> ---------------------------------------------------------------------------
>
> Key: CASSANDRA-6126
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6126
> Project: Cassandra
> Issue Type: Improvement
> Components: Packaging
> Environment: glibc >= 2.10
> Reporter: J. Ryan Earl
> Assignee: Brandon Williams
> Priority: Minor
> Fix For: 2.0.2
>
>
> Cassandra does not take into account particular GLIBC environment variables
> and the nature of the JVM. Cassandra should set the MALLOC_ARENA_MAX
> variable, ideally in cassandra-env.sh, to have something like the following:
> {noformat}
> export MALLOC_ARENA_MAX=${MALLOC_ARENA_MAX:-4}
> {noformat}
> This will limit the number of per-thread memory allocation arenas (ie
> separate memory ranges dedicated to each thread for memory allocation) for
> the new per-thread GLIBC malloc found in distribution like Enterprise Linux 6
> and newer. The net effect is a performance gain, specifically through
> reduced page-table size and kernel overhead of memory management. Without
> the setting, Cassandra will occupy more than double the amount of virtual
> memory space, and due to increased pagetable size, the resident amount of
> memory will also be somewhat larger (~10% or so). For more discussion, see
> HADOOP-7154. Bottom line, cassandra-env.sh need to be setting
> MALLOC_ARENA_MAX to better use system resources.
> In general it can be stated all JVMs should use this environment setting as
> JVMs tend to be highly threaded and manage their own heap. Cassandra and
> Hadoop in particular seem to benefit from my testing.
> More background:
> http://siddhesh.in/journal/2012/10/24/malloc-per-thread-arenas-in-glibc/
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