J. Ryan Earl created CASSANDRA-6126:
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Summary: 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: Config
Environment: glibc >= 2.10
Reporter: J. Ryan Earl
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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