Increasing Permgen size in your Web Server

In previous posts , we had talked about Increasing the Heap size of your server

Here will talk about the Permgen space , how it is different from heap size and why just increasing the heap size will not help you in getting rid of this error 

Java.lang.OutOfMemoryError: PermGen space

The permanent generation should not be ignored, because you need enough memory allocated to it to hold all classes in all of your applications including the JSP’s. So if you have an application which uses a good number of third party libraries , has lot of files , you will definitely need a lot of Permgen space. If you are running two applications on the same server , definitely allocate some good chunk of memory to your Perm gen.

How to increase PermGen?

When you add this line in your catalina.bat or catalina.sh

export JAVA_OPTS=-Xms128m -Xmx192m

It only increase heap size. This is how it would look like (assuming your default PermGen is 64MB)

PermGen does not change

To increase PermGen , it would be

export JAVA_OPTS=-Xms128m -Xmx192m -XX:MaxPermSize=256m

See how the size of PermGen has increased.

Perm Gen increased

This was done on Tomcat 6.0.14

Preventing Tomcat java.lang.OutOfMemoryError: PermGen space failure

The "OutOfMemoryError: PermGen space" message is normally encountered during development activites where a long-running JVM is asked to load/unload builds. However it can also be encountered in a recently spawned JVM under the "right" set of conditions.

The message is a symptom of an incomplete garbage collection sweep where resources are not properly released upon unload/restart.

Tomcat production server sometime will hit the following java.lang.OutOfMemoryError: PermGen space error.

java.lang.OutOfMemoryError: PermGen space
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)


It’s usually happened when the Tomcat start and stop few times. It’s just funny, however you can fine tune it with some minor changes in the Tomcat configuration setting. By default, Tomcat assigned very little memory for the running process, you should increase the memory by make change in catalina.sh or catalina.bat file.

How to fix it?

1) Find where is Cataline.sh located. We need to make some changes in "catalina.sh" file.
P.S Cataline.sh is located at \tomcat folder \bin\catalina.sh

2) Assign following line to JAVA_OPTS variable and add it into catalina.sh file.

JAVA_OPTS="-Djava.awt.headless=true -Dfile.encoding=UTF-8
-server -Xms1536m -Xmx1536m
-XX:NewSize=256m -XX:MaxNewSize=256m -XX:PermSize=256m
-XX:MaxPermSize=256m -XX:+DisableExplicitGC"


Partial example of the catalina.sh file

# JSSE_HOME (Optional) May point at your Java Secure Sockets Extension
# (JSSE) installation, whose JAR files will be added to the
# system class path used to start Tomcat.
#
# CATALINA_PID (Optional) Path of the file which should contains the pid
# of catalina startup java process, when start (fork) is used
#
# $Id: catalina.sh 609438 2008-01-06 22:14:28Z markt $
# -----------------------------------------------------------------------------

JAVA_OPTS="-Djava.awt.headless=true -Dfile.encoding=UTF-8 -server -Xms1536m
-Xmx1536m -XX:NewSize=256m -XX:MaxNewSize=256m -XX:PermSize=256m
-XX:MaxPermSize=256m -XX:+DisableExplicitGC"


# OS specific support. $var _must_ be set to either true or false.
cygwin=false
os400=false
darwin=false
case "`uname`" in
CYGWIN*) cygwin=true;;
OS400*) os400=true;;
Darwin*) darwin=true;;
esac

# resolve links - $0 may be a softlink
PRG="$0"


3) Done. Restart Tomcat.

You should change the “Xms” and “PermSize” value base on your server capability.