On Jan 9, 4:07 pm, "bruce" <bedoug...@earthlink.net> wrote: > thanks jason.... > > or i could also, simply iterate through a loop of the names of the "child > processes" i want to spawn, using the names in the subprocess.popen, and > then proceeding with the rest of your example.. > > question though... if i have a child app that's hanging.. how do i kill it. > > or is this getting into the aspect of using interprocess pipes, where if the > parent isn't getting a 'live ping' via the pipe back from the child after a > certain amount of time... it could kill the child... > > thoughts/comments... > > thanks > > -----Original Message----- > From: python-list-bounces+bedouglas=earthlink....@python.org > > [mailto:python-list-bounces+bedouglas=earthlink....@python.org]on Behalf > Of Jason Scheirer > Sent: Friday, January 09, 2009 3:59 PM > To: python-l...@python.org > Subject: Re: spawning pyhon apps... > > On Jan 9, 3:43 pm, "bruce" <bedoug...@earthlink.net> wrote: > > hi jason.... > > > forgive me... but in your sample: > > my_popenobjects = [subprocess.Popen("foo.py", "--filename=file > > %i.txt"%x) for x in xrange(10)] > > are you spawning 'foo.py' 10 times? that can't be right! > > so just what is "foo.py" used for? what am i missing... > > > it looks like the my_popenobjects array is iterated through to check the > > statuscode. is the statuscode the value that would be returned from a > child > > python script via something like "return(2)".... > > > i've seen mention of os.waitpid(..) does this play into waiting for child > > processes to complete, or determine if they've terminated?? > > > thanks > > > -----Original Message----- > > From: python-list-bounces+bedouglas=earthlink....@python.org > > > [mailto:python-list-bounces+bedouglas=earthlink....@python.org]on Behalf > > Of Jason Scheirer > > Sent: Friday, January 09, 2009 3:19 PM > > To: python-l...@python.org > > Subject: Re: spawning pyhon apps... > > > On Jan 9, 2:47 pm, "bruce" <bedoug...@earthlink.net> wrote: > > > hi... > > > > toying with an idea.. trying to figure out a good/best way to spawn > > multiple > > > python scripts from a parent python app. i'm trying to figure out how to > > > determine when all child apps have completed, or to possibly determine > if > > > any of the child processes have died/halted.. > > > > parent app > > > spawn child1 > > > spawn child2 > > > spawn child3 > > > . > > > . > > > . > > > spawn childn > > > > do i iterate through a os.waitpid(pid) for each pid of the child > processes > > i > > > create? > > > > is there another approach? code samples/tutorial...?? > > > > i've seen various approaches via google, but not just what i'm looking > > for.. > > > > thanks > > > Investigate the subprocess module, you probably want Popen objects. > > You can do a poll loop like > > > my_popenobjects = [subprocess.Popen("foo.py", "--filename=file > > %i.txt"%x) for x in xrange(10)] > > > while any(popenobject.returncode is None for popenobject in > > my_popenobjects): > > time.sleep(0.25) > > > If your tasks are more like function calls and less like shell > > scripts, then investigate writing your python as an importable module > > and use the multiprocessing module, which will do threading/ > > subprocessing for you. > > --http://mail.python.org/mailman/listinfo/python-list > > Correction: statuscode is wrong. It's returncode. > > Foo.py is the hypothetical Python script you want to run in a > subprocess. In this example, I have an external shell script named > foo.py, and I am indeed spawning 10 copies of it, each with a second > argument that varies (foo.py --filename=file0.txt, foo.py -- > filename=file1.txt, ... foo.py --filename=file9.txt). You don't need > os.waitpid() with a Popen object, there is a Popen.wait() method you > can call which will accomplish the exact same thing. I'm polling the > Popen.returncode for each process' return code (which is the numeric > code a process returns when it finishes, like sys.exit(x) or return, > or gives None if it's not done yet. What this sample is doing is > opening 10 copies of the script and running them in parallel, if you > want to run it is serial then you can do a simple for loop and .wait() > on each: > > for cmd in ('a', 'b', 'c'): > sp = subprocess.Popen(cmd) > sp.wait() > print "Command %r completed with status %i" % (cmd, sp.returncode) > > I'm still not 100% sure what you're trying to accomplish. What is the > exact problem you are wishing to solve? > --http://mail.python.org/mailman/listinfo/python-list > >
Yes, so to open your processes you can loop over a list of commands and create new subprocess.Popen(cmd) objects for each. Everything is explained: http://docs.python.org/library/subprocess.html#popen-objects You can do .terminate() to kill a process that may be hanging, you can get the .stdout and poll on its .read() to see if it's still putting anything out to the console. -- http://mail.python.org/mailman/listinfo/python-list
