[jboss-user] [Performance Tuning] - Servers swapping memory

[Suchit Khobarekar]

Suchit Khobarekar [https://community.jboss.org/people/SuchitKhobarekar] created the discussion

"Servers swapping memory"

To view the discussion, visit: https://community.jboss.org/message/795421#795421

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Hi,

We have configured Liferay servers on JBoss AS 7.1.1. We have two environments Stage and Prod which are pretty much identical in terms of the hardware and software. However we are seeing some heavy swapping happening on the Prod servers. About a few hours after the servers are started they start swapping memory and this is how it read (as below):

Memory              Used          Total      Percentage
============================
Physical           4079M       7872M          51%
Actual                3630M       7872M          46%
Swap                    878M   2047M          42%

This is not a good sign for us. The JAVA_OPTS setting in standalone.conf is as below

JAVA_OPTS="$JAVA_OPTS -Dfile.encoding=UTF-8 -Djava.net.preferIPv4Stack=true -Duser.timezone=GMT -server -XX:NewSize=700m -XX:MaxNewSize=700m -Xms2048m -Xmx4096m -XX:MaxPermSize=1536m -XX:SurvivorRatio=6 -XX:TargetSurvivorRatio=90 -XX:MaxTenuringThreshold=15 -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSParallelRemarkEnabled -XX:ParallelGCThreads=16 -XX:+CMSCompactWhenClearAllSoftRefs -XX:CMSInitiatingOccupancyFraction=85 -XX:+CMSScavengeBeforeRemark -XX:+CMSConcurrentMTEnabled -XX:ParallelCMSThreads=2"

There are 2 nodes with 8 GB of RAM each

I found a thread which mentioned that the -Xms and -Xmx should ideally have the same values. This is the thread  https://community.jboss.org/message/221207#221207 https://community.jboss.org/message/221207

Any help on this is really appreciated. I
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