[root@localhost ~]# cat twoproces.py 
#!/usr/bin/env python
from multiprocessing import Process
import os
def output():
 print "My pid is :%d\n" % os.getpid()
 print "My parent is:%d\n" % os.getppid()
def main():
 p=Process(target=output) 
 p.start()
 print "I am parent %d\n" % os.getpid()
if __name__=="__main__":
 main()

[root@localhost ~]# ./twoproces.py 
I am parent 7656
My pid is :7660
My parent is:7656

[root@localhost ~]# cat badprocessID.py 
#!/usr/bin/env python
from multiprocessing import Process
import os
def output(mypid):
 print "I am child %d ID :%d\n" % (os.getpid(),mypid)
def main():
 mypid=os.getpid()
 p=Process(target=output,args=(mypid,)) 
 print "I am parent %d\n" % os.getpid()
 p.start()
if __name__=="__main__":
 main()

[root@localhost ~]# cat simplechina.py 
#!/usr/bin/env python
import os
from multiprocessing import Process
def output(howmany,childpid):
 info = (howmany,os.getpid(),os.getppid(),childpid)
 print "i:%d process ID:%d parent ID%d child ID %d\n" % info
def chain(howmany):
 howmany = howmany-1
 if howmany > 0:
 p = Process(target=chain,args=(howmany,)) 
 p.start()
 output(howmany,p.pid)
def main():
 childpid = 0
 howmany=6
 p = Process(target=chain,args=(howmany,))
 p.start()
if __name__=="__main__":
 main()

[root@localhost ~]# ./simplechina.py 
i:5 process ID:13581 parent ID13580 child ID 13582
i:4 process ID:13582 parent ID13581 child ID 13583
i:3 process ID:13583 parent ID13582 child ID 13584
i:2 process ID:13584 parent ID13583 child ID 13585
i:1 process ID:13585 parent ID13584 child ID 13586

[root@localhost ~]# cat simplefan.py 
#!/usr/bin/env python
import os
from multiprocessing import Process
def output(howmany,childpid):
 info = (howmany,os.getpid(),os.getppid(),childpid)
 print "i:%d process ID:%d parent ID%d child ID %d\n" % info
def fan(i):
 output(i,os.getpid())
def main():
 pList=[]
 for i in range(6):
 p = Process(target=fan,args=(i,))
 pList.append(p)
 for p in pList:
 p.start()
 for p in pList:
 p.join()
if __name__=="__main__":
 main()

[root@localhost ~]# ./simplefan.py 
i:0 process ID:13594 parent ID13593 child ID 13594
i:2 process ID:13596 parent ID13593 child ID 13596
i:3 process ID:13597 parent ID13593 child ID 13597
i:1 process ID:13595 parent ID13593 child ID 13595
i:4 process ID:13598 parent ID13593 child ID 13598
i:5 process ID:13599 parent ID13593 child ID 13599