[All Platforms] Improve documentation examples for cascaded processes

[dinuta]

Consider this example slightly modified from your documentation:

import os
import signal
import psutil

def kill_proc_tree(sig=signal.SIGTERM, include_parent=False,
                   timeout=None, on_terminate=None):
    """Kill a process tree (including grandchildren) with signal
    "sig" and return a (gone, still_alive) tuple.
    "on_terminate", if specified, is a callabck function which is
    called as soon as a child terminates.
    """
    parent = psutil.Process(os.getpid())
    children = parent.children(recursive=True)
    if include_parent:
        children.append(parent)
    for p in children:
        p.send_signal(sig)
    gone, alive = psutil.wait_procs(children, timeout=timeout,
                                    callback=on_terminate)
    return (gone, alive)

1. os.getpid() is the Flask microservice
2. The service parent process opens childs using another python script in detached mode with p = subprocess.Popen(PYTHON_SCRIPT, env=CmdUtils.__env.get_env_and_virtual_env())
3. The PYTHON_SCRIPT is running system commands with variable run times (from milliseconds to minutes/hour...).

The problem is that the above piece of code will raise an error for the processes that were closed very fast.

Please revisit the examples and documentation.

[giampaolo]

Good catch.