Out Of Memory Errors

Contents

[edit]

java.lang.OutOfMemoryError: PermGen space

This error will appear after Tomcat has exhausted all of its memory. This is typically caused by using the "Update" or "Reload" function on a webapp too many times. Currently, Tomcat and/or the JVM isn't releasing all of the memory when a webapp is destroyed/recreated. After several reloads Tomcat is out of its allotted memory and will hang or freeze.

[edit]

Solutions

  • Developers: Restart Tomcat after several updates/reloads
  • Developers and Implementers: Allow Tomcat to use more memory. This will not stop the error, just prolong times between tomcat restarts. Follow the 'Java Heap Size' solution instructions.
  • Implementers: Tell Tomcat to not leak memory
[edit]

Java Heap Size Exception

A Java Heap Size error occurs because of certain memory intensive actions (like Data Exporting). The new Spring managed API uses a lot of memory to cache the xml beans. You may need to increase the default memory allocation.

[edit]

Solutions

Three options for increasing Tomcat's allowed memory:

  • Start Tomcat with the parameters:
    -Xmx512m -Xms512m -XX:PermSize=256m -XX:MaxPermSize=256m -XX:NewSize=128m
    at the command line. (The current ANT task "Start Tomcat" will start with these options.)
  • OR, if running Tomcat as a Windows Service, open up the Tomcat Monitor (TOMCAT_HOME/bin/tomcat5w.exe) → Configure → Java → Java Options. Append:
    -Xmx512m
    -Xms512m
    -XX:PermSize=256m
    -XX:MaxPermSize=256m
    -XX:NewSize=128m
    Note: if you copy and paste the above into tomcat monitor, make sure that it doesn't insert an extra space at the end of each line, or tomcat will fail to start.
  • OR, if running Tomcat as a Linux daemon, open the /etc/init.d/Tomcat.sh script and add the the parameters to the CATALINA_OPTS:
    If CATALINA_OPTS is already set to this: CATALINA_OPTS="-Djava.library.path=/opt/tomcat/lib/.libs"
    Then change it to this:
    CATALINA_OPTS="-Djava.library.path=/opt/tomcat/lib/.libs -Xmx512m -Xms512m -XX:PermSize=256m -XX:MaxPermSize=256m -XX:NewSize=128m"

Solution for Tomcat memory leak:

  • In <TOMCAT HOME>/conf/web.xml file, in the jsp servlet definition add the following element:
    <init-param>
      <param-name>enablePooling</param-name>
      <param-value>false</param-value>
    </init-param>
[edit]

Finding Memory Solutions

OpenMRS developers use YourKit Profiler to discover and debug memory and cpu consumption.

YourKit is kindly supporting OpenMRS with its full-featured Java Profiler. YourKit, LLC is creator of innovative and intelligent tools for profiling Java and .NET applications. Take a look at YourKit's leading software products: YourKit Java Profiler and YourKit .NET Profiler.

Retrieved from "http://openmrs.org/wiki/Out_Of_Memory_Errors"