I use the signal function to kill all sub-processes in the mul-process program, the code is shown blow, save as a file named mul_process.py:

import time
import os
import signal
from multiprocessing import Process

processes = []

def fun(x):
    print 'current sub-process pid is %s' % os.getpid()
    while True:
        print 'args is %s' % x
        time.sleep(100)

def term(sig_num, frame):
    print 'terminate process %d' % os.getpid()
    for p in processes:
        print p.pid
    try:
        for p in processes:
            print 'process %d terminate' % p.pid
            p.terminate()
            p.join()
    except Exception as e:
        print str(e)

if __name__ == '__main__':
    print 'current main-process pid is %s' % os.getpid()
    for i in range(3):
        t = Process(target=fun, args=(str(i),))
        t.start()
        processes.append(t)
    signal.signal(signal.SIGTERM, term)
    try:
        for p in processes:
            p.join()
    except Exception as e:
        print str(e)

Using 'python mul_process.py' to launch the program on Ubuntu 10.04.4 and Python 2.6, when it start running, in another tab, I use kill -15 with the main process pid to send signal SIGTERM to kill all processes, when the main process receive the signal SIGTERM, it exit after terminate all sub processes, but when I use kill -15 with the sub process pid, it does not work, the program still alive and running as before, and does not print the sentence defined in the function term, seems that the subprocess doesn't receive the SIGTERM.As I know, the sub process will inherit the signal handler, but it doesn`t work, here is the first question.

And then I move the line 'signal.signal(signal.SIGTERM, term)' to position after line 'if name == 'main':', like this:

if __name__ == '__main__':
    signal.signal(signal.SIGTERM, term)
    print 'current main-process pid is %s' % os.getpid()
    for i in range(3):
        t = Process(target=fun, args=(str(i),))
        t.start()
        processes.append(t)
    try:
        for p in processes:
            p.join()
    except Exception as e:
        print str(e) 

Launch the program, and use kill -15 with the main process pid to send the signal SIGTERM, the program receive the signal and call the function term but also doesn't kill any subprocessed and exit itself, this is the second question.