E-mail
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=128mat 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=128mNote: 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.Note: If running 64 bit version of Tomcat, you have to edit the Windows Registry HKEY_LOCAL_MACHINE\SOFTWARE\Apache Software Foundation\Procrun 2.0\Tomcat5\Parameters\JavaJVM settings in Registry
- OR, if running Tomcat as a Linux daemon, open the /etc/init.d/Tomcat.sh script and append the parameters to the CATALINA_OPTS variable: i.e. 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.