More for my own reference than anything else, a means to establish which java thread is using CPU time on Linux.
- Get the process ID (PID) using ps -ef
- Enter the command
- Press shift-h
- All threads in the parent java process should start to appear with their lightweight process IDs and CPU usage - this takes some time
- Now send a
kill -3 <pid>to the process - this will trigger a thread dump without ending the process.
CTL-\will also work if you have java running in a console.
- Convert the PIDs of the lightweight process you are interested in into hex (so 2042 = 0x7FA)
- Find the file where the Java process was sending system.out and grep for
nid=<lightweight pid in hex>