Often time, Tomcat may hits 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 after the Tomcat restarts a few times.

1. Solution

By default, Tomcat is assigned a very little PermGen memory for the running process. To fix it, increase the PermGen memory settings by using the following Java VM options.

-XX:PermSize<size> - Set initial PermGen Size.
-XX:MaxPermSize<size> - Set the maximum PermGen Size.

In the next step, we will show you how to set the VM options in Tomcat, under Windows and Linux environment.

2. Windows

Tomcat is managed by this script file catalina.bat, dive inside the script, you will find out that catalina.bat always find and run the setenv.bat file to set the environment variables.

rem Get standard environment variables
if not exist "%CATALINA_BASE%\bin\setenv.bat" goto checkSetenvHome
call "%CATALINA_BASE%\bin\setenv.bat"
goto setenvDone
if exist "%CATALINA_HOME%\bin\setenv.bat" call "%CATALINA_HOME%\bin\setenv.bat"

2.1 To set the environment variable on Windows, create a setenv.bat manually, and put it into the ${tomcat-folder}\bin folder.

set JAVA_OPTS=-Dfile.encoding=UTF-8 -Xms128m -Xmx1024m -XX:PermSize=64m -XX:MaxPermSize=256m

P.S No double quotes, set JAVA_OPTS={value}.

2.2 Restart Tomcat, it will call the setenv.bat file to set the environment variable automatically.

{$tomcat-folder}\bin\catalina.bat restart

3. Linux

On Linux, the process is same, just Tomcat is using catalina.sh and setenv.sh instead.

3.1 Find out where is catalina.sh :

$ sudo find / -name "catalina.sh"
find: /dev/fd/3: Not a directory
find: /dev/fd/4: Not a directory

3.2 Review the catalina.sh, script, it behaves like Windows, but use setenv.sh instead.

# Ensure that any user defined CLASSPATH variables are not used on startup,
# but allow them to be specified in setenv.sh, in rare case when it is needed.
if [ -r "$CATALINA_BASE/bin/setenv.sh" ]; then
  . "$CATALINA_BASE/bin/setenv.sh"
elif [ -r "$CATALINA_HOME/bin/setenv.sh" ]; then
  . "$CATALINA_HOME/bin/setenv.sh"

3.3 Create a setenv.sh manually, and put it into the ${tomcat-folder}\bin\ folder.

export JAVA_OPTS="-Dfile.encoding=UTF-8 -Xms128m -Xmx1024m -XX:PermSize=64m -XX:MaxPermSize=256m"

P.S With double quotes, export JAVA_OPTS=”{value}”.

3.4 Restart Tomcat.

The heap size and non-heap size (perm gen) value is just an example, you should change the value accordingly to suit your project needs.


  1. Configure Tomcat Memory Settings
  2. Oracle : Presenting the Permanent Generation
  3. Useful JVM Flags – Part 5 (Young Generation Garbage Collection)
  4. How To Install Tomcat On Ubuntu
  5. Find Out Your Java Heap Memory Size
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