grep Exception SystemOut.log | wc -l

I'm reminded today that after performance tests a simple check exists especially when adding more JVMs to a cluster.  Count the number of exceptions in the log files.  Of course, clear the logs before running the test.  If the counts are not all roughly the same (or significantly skewed from the other app servers) then it is clear there are issues with that JVM that need to be checked.  Sometimes it is configuration or a misplaced JAR file.