Nothing new - Debugging UNIX Java process

Nothing is new here. Bits and pieces put together to debug Java process on resource management, thread dump and manually kill the process. I always develop software on Windows platform, but need to port to UNIX platform. Once moved to UNIX, ya hoooo... i see problem. How to solve ? :(

Step 1: Find out process id. Use "ps" command and "grep" command, this works great

Linux:
ps -aef | grep <java execution>>
Example: ps -aef | grep com.test.TestRunner
HP Unix:
ps -aefx | grep <java execution>

Result:
test 17559 17548 0 Oct01 pts/1 00:00:00 -ksh

Now get PID (Process ID) from the result, second column indicates process id (third column is the process which started this process)

Step 2: Find out what are all the resources used by the process (all the socket connections)

lsof -p <PID>
Example: lsof -p 17559

This result will give number of open files, TCP connections and UDP connections. This gives better insight of the process and its current status. We can solve most of the issues by seeing the resource usage snippet.

Step 3: This isnt enough to conclude, need to get better idea of the process. Get a thread dump.

kill -3 <PID>

This will not kill the process, this will dump output into .out files. Always start the process by redirecting results into .out file

nohup java com.test.TestRunner > testrunner.out &

This gives great insight of each thread and dead lock details.

Step 4: We are done with the analysis, need to start the process again to find out other problems :) , so kill the process

kill -9 <PID>

SIGQUIT is also another way to debug, i used long before dont remember now.