I need to make script which on some condition spawns parallel proccess (worker) and makes it to do some IO job. And when it finished - close that process.
But looks like the processes do not tend co exit by default.
Here is my approach:
pool = multiprocessing.Pool(4)
r = pool.map_async(f, [1,2,3,4,5,6,7,8,9,10])
Pool spawns worker processes when you declare the pool. They do not get killed until the pool is shut down. Instead, they wait there for more work to appear in the queue.
If you change your code to:
r = pool.map_async(f, [1,2,3,4,5,6,7,8,9,10]) pool.close() pool.join() print "check ps ax now" sleep (10)
you will see the pool processes have disappeared.
Another thing, your program might not work as intended as you declare function f after you declare your pool. I had to change pool = multiprocessing.Pool(4) to follow function f declaration, but this may vary between Python versions. Anyway, if you get odd "module has no attribute" -exceptions, this is the reason.