Python – Auto kill process and child process of multiprocessing Pool

I am using multiprocessing module for parallel processing.
Bellow code snippet search the string filename in X location and return the file name where the string found.
But in some cases it take long time to search process so i was trying to kill the search process with take more than 300 seconds.For that i used timeout == 300 as given bellow , this kills the search process but it dosent kill the child process spawn by bellow code.

I tried to find multiple way but no success :/

How can i kill parent process from Pool along with its child process ?

import os
from multiprocessing import Pool

def runCmd(cmd):
     lresult = os.popen(cmd).read()
     return lresult

main ():
     p = Pool(4)
     data_paths = [list of paths of store data]
     search_cmds = [ "SearchText.exe %s < %s"%(data_path, filename) for data_path in data_paths ]
     results = [p.apply_async(runCmd, (cmd,), callback = log_result) for cmd in search_cmds]
     try:
        for result in results:
            root.append(result.get(timeout=300))
        #rool holds the result of search process
     except TimeoutError:
        for c in multiprocessing.active_children():
            print '----->',c.pid
            os.kill(c.pid, signal.SIGTERM)
     p.close()
     p.join()

if __name__ == '__main__':
    main()

Process Tree in Process Explorer :

cmd.exe
------python.exe
----------------python.exe
--------------------------cmd.exe
---------------------------------SearchText.exe
----------------python.exe
--------------------------cmd.exe
---------------------------------SearchText.exe
----------------python.exe
--------------------------cmd.exe
---------------------------------SearchText.exe
----------------python.exe
--------------------------cmd.exe
---------------------------------SearchText.exe

above code snippet dosnt kill the child process

--------------------------cmd.exe
---------------------------------SearchText.exe
--------------------------cmd.exe
---------------------------------SearchText.exe
--------------------------cmd.exe
---------------------------------SearchText.exe
--------------------------cmd.exe
---------------------------------SearchText.exe

Theses child search process retain , these child process also get killed .

Please guild.

Thanks