[jboss-jira] [JBoss JIRA] (WFCORE-2960) Export a low MALLOC_ARENA_MAX value in standalone.conf and domain.conf

[Brian Stansberry (JIRA)]

Brian Stansberry created WFCORE-2960:
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             Summary: Export a low MALLOC_ARENA_MAX value in standalone.conf and domain.conf
                 Key: WFCORE-2960
                 URL: https://issues.jboss.org/browse/WFCORE-2960
             Project: WildFly Core
          Issue Type: Enhancement
          Components: Scripts
            Reporter: Brian Stansberry
            Assignee: Tomaz Cerar


This is a task that came out of research done by [~andy.miller] on WF/EAP memory use in cloud environments.

Our launch scripts for *nix environments should set MALLOC_ARENA_MAX, e.g.

export MALLOC_ARENA_MAX=${MALLOC_ARENA_MAX:-1}

See http://info.prelert.com/blog/java-8-and-virtual-memory-on-linux for background.

The default glibc settings of allowing up to 128 malloc arenas make very little sense for a java application, since the vm asks the os for a few large memory allocations and then manages those areas itself. Leaving that default setting in place will result in a very large virtual memory size for the VM. It's just virtual, not resident, memory, so controlling this to a large extent is just a matter of having a better image for people who don't understand the distinction. But as is mentioned in the linked blog post's discussion of mlockall() and Elasticsearch, there may be some more concrete implications as well.

The initial recommendation on this was to set the value to 1, but this bears some research/discussion. For example hadoop uses 4 (https://issues.apache.org/jira/browse/HADOOP-7154), and a bit of googling of "MALLOC_ARENA_MAX java" leads to some entries mentioning using 2 or 3.





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