JVM settings and recommendations

Tigase configuration file tigase.conf (described in more detail in the section called “Startup File for tigase.sh - tigase.conf”) mentioned a couple of environmental variables which are related to the operation of the JVM. In this guide we would like to expound on those configuration options and provide hints for the optimal settings.

Settings included in the etc/tigase.conf are as follows:

#GC="-XX:+UseBiasedLocking -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:NewRatio=2 -XX:+CMSIncrementalMode -XX:-ReduceInitialCardMarks -XX:CMSInitiatingOccupancyFraction=70 -XX:+UseCMSInitiatingOccupancyOnly"
#EX="-XX:+OptimizeStringConcat -XX:+DoEscapeAnalysis -XX:+UseNUMA"

#GC_DEBUG=" -XX:+PrintTenuringDistribution -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintGCTimeStamps -Xloggc:logs/jvm.log -verbose:gc "

#PRODUCTION_HEAP_SETTINGS=" -Xms5G -Xmx5G " # heap memory settings must be adjusted on per deployment-base!

And while this file utilizes bash variables, JVM configuration options can be used in the same manner on all operating systems.

The guide will consists of two main parts - memory settings and Garbage Collector tweaks descriptions and hints.

We recommend using -server JVM parameter in all cases.