Fix Apache Tomcat: java.lang.OutOfMemoryError: PermGen spaceError

java.lang.OutOfMemoryError: PermGen space

There are many reasons that you may get an OutOfMemoryError when you are running your application in Apache Tomcat server.

1. Too many classes loaded in PermGen area.
2. Memory leaks in your application.
3. Trying to parse a huge file in memory.
4. Using DOM XML parser to parse a huge XML file.
5. Huge resultset received from Database.

You get this error when the PermGen memory area is full. The PermGen area is the part of the Java heap that is used to store information related to metadata like class declarations, methods and object arrays.

How to fix PermGen Error

Its also recommended to use profiling tools such as jconsole to see which classes are taking up space. If you think its due to the size allocated from PermGen using the JVM argument, then change them as follows in the Tomcat configuration file,

1. Open Tomcat -> bin directory.
2. Create a file named "setenv.bat" if on Windows or setenv.sh for macOS/Linux/Unix,
3. Add the below lines in the file.
   
   Windows

   set "JAVA_OPTS=%JAVA_OPTS% -Xms512m -Xmx1024m -XX:MaxPermSize=512m -server"

   
   macOS/Linux/Unix

   export "JAVA_OPTS=%JAVA_OPTS% -Xms512m -Xmx1024m -XX:MaxPermSize=512m -server"

4. Restart tomcat.