IO timeout in threaded application

[Gordon Messmer]

Gordon Messmer wrote:
> The other approach I'd thought about would be to open a pipe and fork a 
> process to do the check.  The external process could handle signals 
> properly.


This almost works right, except that the new pid ends up as a zombie... 
  Why doesn't the main thread reap the status of this process?  I don't 
get zombies if I start a thread and use os.system() or os.popen2() (both 
  of which should also fork & exec):

 >>> def test2():
...     child=os.fork()
...     if not child:
...             print "newpid", os.getpid()
...             time.sleep(30)
...             print 'returning from test2'
...             os._exit(0)
...
 >>> import thread
 >>> thread.start_new_thread( test2, () )
1125342512
 >>> newpid 21072
returning from test2


$ ps axfm| grep python
21060 pts/2    S      0:00  |   \_ python
21072 pts/2    Z      0:00  |       \_ [python <defunct>]