Use ProcFS for memory and cpu usage on compatible OSes

[BenoitHanotte]

Currently Babar relies on the JVM intrumentation to get Memory and CPU data through the provided MXBean interface. However this brings the following limitations:

• only JVM information is available (eg: no sub-processes)
• off-heap memory is potentially not correctly accounted for
• JVM memory values are not the same as the values YARN uses to account for physical & virtual memory

This tickets proposes to use, on compatible systems, the proc filesystem to get for the process subtree (JVM and all sub-processed):

• RSS memory (rss pages * page size)
• virtual memory
• cpu time (user mode)
• cpu time (kernel mode)

The proc man page is available at http://man7.org/linux/man-pages/man5/proc.5.html

[BenoitHanotte]

Done with ProcFSProfiler