Tried to run jinfo on my Ubuntu 12.04 and got this error message:
$ ./jinfo <vmid> Error attaching to process: sun.jvm.hotspot.debugger.DebuggerException: Can't attach to the process
enabled debugging:
echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope
and tried again:
$ ./jinfo <vmid> Attaching to process ID <vmid>, please wait... Debugger attached successfully. Server compiler detected. ... ... $
Solution found here:
http://blog.thecodingmachine.com/fr/content/fixing-java-memory-leaks-ubuntu-1104-using-jmap