"Horrible Exception: null"
chen yang
Herrick, Rick
This is actually a Tomcat issue. The Tomcat configuration on the workshop VM is not tuned AT ALL. You can modify the file /etc/default/tomcat6 to configure the JVM heap settings. I’m not sure what the default state of this setting is, but what I currently have configured is:
JAVA_OPTS="-Djava.awt.headless=true -XX:+UseConcMarkSweepGC -Xms170m -Xmx512m -Xmn102m"
You can try bumping up that max value (the -Xmx option) to 1024m or something like that, but you should only do that if you set the physical memory available to the VM to 2GB or higher in your virtualization settings (i.e. VMWare or VirtualBox or whatever you’re using to run the VM).
The other possibility is that you might see PermGen errors. The PermGen space is actually another heap that’s used by the JVM for object allocation. When you increase your standard heap, you usually need to increase your permgen size. This uses the option:\
-XX:MaxPermSize= XXXm
I’ve read all kinds of guidelines on what that XXX number should be, but for a server under load the only thing I’ve found that’s a good solid rule is trial and error. With the PermGen space, you don’t want to just jack it way up and call it a day. That can lead to major performance degradation, as it gives the Java garbage collector too much junk to manage. So try setting that to a number, maybe 25% of your max heap space and increasing it from there as you run into PermGen errors. Don’t do this in production of course J
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Herrick, Rick
BTW, that “Horrible exception” message is not ours, it’s directly from Tomcat.