finding child cpu usage of a running child

[Karthik Gurusamy]

Hi,

Wondering if there is a way to measure a child process's cpu usage
(sys and user) when the child is still running. I see os.times()
working fine in my system (Linux 2.6.9-42.7.ELsmp), but it gives valid
data only after the child has exited. When the child is alive,
os.times() data for child is zero for both child-sys and child-user
cpu.

My script (process P1) launches child process P2 (using
popen2.Popen3). P2 is a long running process (big compilation). Every
minute or so, from P1, I want to measure how much cpu P2 has consumed
and based on that I can make some estimate on the completion time of
P2 (I have a rough idea how much total cpu P2 needs to complete).

I understand it may be too expensive to update this information to the
parent process when any of the child/grand-child completes; but
wondering if any there is any way to get this info; the expensive
operations is on-demand only when the request is made.

Thanks,
Karthik