memoru usage of process

[Jacek Popławski]

I need to know how much memory uses child process (after 
subprocess.Popen), so I want function:

get_memory_usage(pid)

I found two ways:

- call "ps" and analyze its output - this is not portable (different 
output on Linux, Cygwin and QNX)

- use resource.getrusage - but it works for self/children, not for 
single process with given pid

Do you know any ideas how to do it in Python?