Set Tomcat Memory Heap Size

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If your Java Web Application running on Tomcat ever crashes and throws the exception:

SEVERE: Servlet.service() for servlet WebAppServlet threw exception
java.lang.OutOfMemoryError: Java heap space

, you need to increase the allocated memory that Tomcat has for running applications. This is accomplished by adding "-Xms256m -Xmx512m" to the catalina.sh file found in the "bin" directory of the Tomcat installation, where 256 and 512 should be replaced with appropriate values for your application. Xms mean starting heap size and Xmx means maximum heap size. I was able to increase the memory allocated to Tomcat on a Mac running Mac OS X Leopard with Tomcat 6.0.20 installed. These instructions should work for any *nix machine, but I can't guarantee it.

Step 1: Open up the catalina.sh file with any text editor.

Step 2: Search for "JAVA_OPTS=" in the file and in particular locate the following lines of code:


if [ -z "$LOGGING_MANAGER" ]; then
JAVA_OPTS="$JAVA_OPTS -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager"
else
JAVA_OPTS="$JAVA_OPTS $LOGGING_MANAGER"
fi


Step 3: At the end of the JAVA_OPTS definitions add "-Xms256m -Xmx512m".


if [ -z "$LOGGING_MANAGER" ]; then
JAVA_OPTS="$JAVA_OPTS -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Xms256m -Xmx512m"
else
JAVA_OPTS="$JAVA_OPTS $LOGGING_MANAGER -Xms256m -Xmx512m"
fi


Step 4: Save the file and restart Tomcat.


Piece of Cake!!