Today I met a strange issue while installing hadoop on a linux machine.

I started all the processes, it was working fine also, but those processes were not listed in jps. I struggled with issue for some time, later I found the solution. The reason was because, some files like hsperfdata_<username> were present in /tmp folder. I deleted those files, after that jps listed all the running processes.. 🙂

Actually this hsperfdata_ is a feature Not bug. It’s a log directory created by jvm while running and its a part of Java performance counter. This folder created inside tmp folder of any operating system by default.
JVM uses this folder for process monitoring.
This folder contains perfdata corresponding to java process id running from user mentioned in hsperf Data folder name.