multiprocessing.Pool: When to use apply, apply_async or map?

Question

I have not seen clear examples with use-cases for Pool.apply, Pool.apply_async and Pool.map. I am mainly using Pool.map; what are the advantages of others?

Answer 1

Regarding apply vs map:

pool.apply(f, args): f is only executed in ONE of the workers of the pool. So ONE of the processes in the pool will run f(args).

pool.map(f, iterable): This method chops the iterable into a number of chunks which it submits to the process pool as separate tasks. So you take advantage of all the processes in the pool.