My 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)
        at org.apache.catalina.loader.WebappClassLoader.findClassInternal
(WebappClassLoader.java:1847)
        at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:873)
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1326)
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1205)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:620)

It’s usually happening when my Tomcat start and stop few time. It’s just funny, however we can fine tune it with some minor changes in Tomcat configuration setting. By default, Tomcat assigned very little memory for the running process. We need to 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 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.

P.S Change Xms and PermSize base on your server capability.