High CPU Utilization in java application - why?

If a profiler is not applicable in your setup, you may try to identify the thread following steps in this post.

Basically, there are three steps:

1. run top -H and get PID of the thread with highest CPU.
2. convert the PID to hex.
3. look for thread with the matching HEX PID in your thread dump.

You may be victim of a garbage collection problem.

When your application requires memory and it's getting low on what it's configured to use the garbage collector will run often which consume a lot of CPU cycles.If it can't collect anything your memory will stay low so it will be run again and again.When you redeploy your application the memory is cleared and the garbage collection won't happen more than required so the CPU utilization stays low until it's full again.

You should check that there is no possible memory leak in your application and that it's well configured for memory (check the -Xmx parameter, see What does Java option -Xmx stand for?)

Also, what are you using as web framework? JSF relies a lot on sessions and consumes a lot of memory, consider being stateless at most!

In the thread dump you can find the Line Number as below.

for the main thread which is currently running...

"main" #1 prio=5 os_prio=0 tid=0x0000000002120800 nid=0x13f4 runnable [0x0000000001d9f000]   java.lang.Thread.State: **RUNNABLE**    at java.io.FileOutputStream.writeBytes(Native Method)    at java.io.FileOutputStream.write(FileOutputStream.java:313)    at com.rana.samples.**HighCPUUtilization.main(HighCPUUtilization.java:17)**