When JBoss, or any Java application, runs into OutOfMemory error, you should exit your app and fix the real issue that cause it to consume that much memory. Don't just simply restarting the server and hope it go away by itself!

Either fix it by increase your JBoss server heap memory size to reach your need, or fix your app that runs on JBoss to use less memory.

Google Java options on -Xmx usage.