Tomcat 7: How to set initial heap size correctly?

I was trying to adjust initial heap size of a tomcat 7 (CentOS, java -version: 1.6.0_25-b06) instance by adding the following line to catalina.sh:

export CATALINA_OPTS="-Xms=512M -Xmx=1024M"

Starting up tomcat fails and logs the following message to catalina.out:

Invalid initial heap size: -Xms=512m
Could not create the Java virtual machine.

What is wrong with these options?

You must not use =. Simply use this:

export CATALINA_OPTS="-Xms512M -Xmx1024M"

Use following command to increase java heap size for tomcat7 (linux distributions) correctly:

echo 'export CATALINA_OPTS="-Xms512M -Xmx1024M"' > /usr/share/tomcat7/bin/setenv.sh

You might no need to having export, just add this line in catalina.sh :

CATALINA_OPTS="-Xms512M -Xmx1024M"

setenv.sh is better, because you can easily port such configuration from one machine to another, or from one Tomcat version to another. catalina.sh changes from one version of Tomcat to another. But you can keep your setenv.sh unchanged with any version of Tomcat.

Another advantage is, that it is easier to track the history of your changes if you add it to your backup or versioning system. If you look how you setenv.sh changes along the history, you will see only your own changes. Whereas if you use catalina.sh, you will always see not only your changes, but also changes that came with each newer version of the Tomcat.

Go to "Tomcat Directory"/bin directory

if Linux then create setenv.sh else if Windows then create setenv.bat

content of setenv.* file :

export CATALINA_OPTS="$CATALINA_OPTS -Xms512m"
export CATALINA_OPTS="$CATALINA_OPTS -Xmx8192m"
export CATALINA_OPTS="$CATALINA_OPTS -XX:MaxPermSize=256m"

after this restart tomcat with new params.

explanation and full information is here

http://crunchify.com/how-to-change-jvm-heap-setting-xms-xmx-of-tomcat/