proc = Popen(child_command, stdin=None, stdout=None, stderr=None, env=None, shell=True)

vmpeak = -1
while proc.returncode == None:
    vmpeak = max(get_vsize(sid), vmpeak)
    log("Waiting for child to exit. vmpeak={}".format(vmpeak))
    proc.poll()
    sleep(0.1) # Time in seconds (float)

out.write("memusg: vmpeak: {} kbn".format(vmpeak))