process - Python What is the difference between a Pool of worker processes and just running multiple Processes? -

i not sure when use pool of workers vs multiple processes.

processes = []  m in range(1,5):        p = process(target=some_function)        p.start()        processes.append(p)  p in processes:        p.join() 

vs

if __name__ == '__main__':     # start 4 worker processes     pool(processes=4) pool:         pool_outputs = pool.map(another_function, inputs) 

as says on pymotw:

the pool class can used manage fixed number of workers simple cases work done can broken , distributed between workers independently.

the return values jobs collected , returned list.

the pool arguments include number of processes , function run when starting task process (invoked once per child).

please have @ examples given there better understand application, functionalities , parameters.

basically pool helper, easing management of processes (workers) in cases need consume common input data, process in parallel , produce joint output.

the pool quite few things otherwise should code (not hard, still, it's convenient find pre-cooked solution)

i.e.

• the splitting of input data
• the target process function simplified: can designed expect 1 input element only. pool going call providing each element subset allocated worker
• waiting workers finish job (i.e. joining processes)
• ...
• merging output of each worker produce final output