added some comment

binarycpython/utils/grid.py

@@ -812,7 +812,7 @@ class Population(object):
         # TODO: calculate the chunksize value based on: total starcount and cores used. 
         r = list(p.imap_unordered(evolve_system, yield_system(), chunksize=20))
 
-        # Handle clean termination of the whole multiprocessing
+        # Handle clean termination of the whole multiprocessing (making sure there are no zombie processes (https://en.wikipedia.org/wiki/Zombie_process))
         p.close()
         p.join()