Increasing the Memory used by Tomcat in Linux

Following on from my blog entry on installing Java 5 and Tomcat entry here on Linux and then moving the shutdown port so I could have to versions of Tomcat, blog entry here. So After doing that my next step was to increase the memory to my version of Tomcat on Linux

The basic premise of increasing the memory Tomcat uses is by increasing the memory the JVM Tomcat uses. You do this by passing in some variables to the JVM. You can see a list of the variables you pass in by doing on a dos or terminal

Java -X

You probably won’t need to use these settings very often, Tomcat on windows sets these automatically and IDE’s have usually slapped a nice GUI for you to use but in the end they are usually setting up the values passed to the JVM on initialisation. Except when you use Linux where you have to start getting your hands dirty because there aren’t many nice GUI’s to help you out.

The two main settings I am interested in for increasing the memory in Tomcat are

-Xms sets the initial Java heap size in megabytes
-Xmx sets the maximum Java heap size in megabytes

So how do we get these changes into Tomcat, well the answer is we have to change the Catalina.sh and add in the extra memory allocation into the JAVA_OPTS variable. I have read that you can also add values to the CATALINA_OPTS but when I tried I couldn’t get it to work so I decided to use the JAVA_OPTS instead. Below are the instructions how I increased the memory for my Tomcat on Linux

I edited the file

catalina.sh

which can be found here or where ever you tomcat home is

/usr/local/tomcat/bin

I edited the line

# Set juli LogManager if it is present
if [ -r "$CATALINA_HOME"/bin/tomcat-juli.jar ]; then
JAVA_OPTS="$JAVA_OPTS "-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager"

"-Djava.util.logging.config.file="$CATALINA_BASE/conf/logging.properties"
fi

to

# Set juli LogManager if it is present
if [ -r "$CATALINA_HOME"/bin/tomcat-juli.jar ]; then
JAVA_OPTS="$JAVA_OPTS "-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager" "-Xms256m"

"-Xmx512m"

"-Djava.util.logging.config.file="$CATALINA_BASE/conf/logging.properties"
fi

I have added the two variables which are passed to the JVM when starting Tomcat and they are memory settings

"-Xms256m"
"-Xmx512m"

-Xms sets the initial Java heap size in megabytes
-Xmx sets the maximum Java heap size in megabtyes

saved the file and then stopped and started the tomcat server

to test that the changed had worked I went to the tomcat manager

http://localhost:8181/manager/html

and then clicked on the Server Status hyperlink and half way down the page you will see some information regarding the JVM
JVM

Free memory: 1.66 MB Total memory: 8.30 MB Max memory: 508.06 MB