os.wait() losing child?

[Jason Zheng]

Greg,

That explains it! Thanks a lot for your help. I guess this is something 
they do to prevent zombie threads?

~Jason

greg wrote:
> Jason Zheng wrote:
>> Hate to reply to my own thread, but this is the working program that 
>> can demonstrate what I posted earlier:
> 
> I've figured out what's going on. The Popen class has a
> __del__ method which does a non-blocking wait of its own.
> So you need to keep the Popen instance for each subprocess
> alive until your wait call has cleaned it up.
> 
> The following version seems to work okay.
> 
> import os
> from subprocess import Popen
> 
> pids = {}
> counts = [0,0,0]
> p = [None, None, None]
> 
> for i in xrange(3):
>   p[i] = Popen('sleep 1', shell=True)
>   pids[p[i].pid] = i
>   print "Starting child process %d (%d)" % (i,p[i].pid)
> 
> while (True):
>   (pid,exitstat) = os.wait()
>   i = pids[pid]
>   del pids[pid]
>   counts[i]=counts[i]+1
> 
>   #terminate if count>10
>   if (counts[i]==10):
>     print "Child Process %d terminated." % i
>     if reduce(lambda x,y: x and (y>=10), counts):
>       break
>     continue
> 
>   print "Child Process %d (%d) terminated, restarting" % (i, pid),
>   p[i] = Popen('sleep 1', shell=True)
>   pids[p[i].pid] = i
>   print "(%d)" % p[i].pid
> 
> -- 
> Greg