title: multiprocessing.Pool: When to use apply, apply_async or map?
body: <p>I have not seen clear examples with use-cases for <a href="https://docs.python.org/2/library/multiprocessing.html#multiprocessing.pool.multiprocessing.Pool.apply" rel="noreferrer">Pool.apply</a>, <a href="https://docs.python.org/2/library/multiprocessing.html#multiprocessing.pool.multiprocessing.Pool.apply_async" rel="noreferrer">Pool.apply_async</a> and <a href="https://docs.python.org/2/library/multiprocessing.html#multiprocessing.pool.multiprocessing.Pool.map" rel="noreferrer">Pool.map</a>. I am mainly using <code>Pool.map</code>; what are the advantages of others?</p>