diff -r ffa851df0825 -r 2fb8b9db1c86 symbian-qemu-0.9.1-12/python-2.6.1/Doc/includes/mp_workers.py --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/symbian-qemu-0.9.1-12/python-2.6.1/Doc/includes/mp_workers.py Fri Jul 31 15:01:17 2009 +0100 @@ -0,0 +1,87 @@ +# +# Simple example which uses a pool of workers to carry out some tasks. +# +# Notice that the results will probably not come out of the output +# queue in the same in the same order as the corresponding tasks were +# put on the input queue. If it is important to get the results back +# in the original order then consider using `Pool.map()` or +# `Pool.imap()` (which will save on the amount of code needed anyway). +# + +import time +import random + +from multiprocessing import Process, Queue, current_process, freeze_support + +# +# Function run by worker processes +# + +def worker(input, output): + for func, args in iter(input.get, 'STOP'): + result = calculate(func, args) + output.put(result) + +# +# Function used to calculate result +# + +def calculate(func, args): + result = func(*args) + return '%s says that %s%s = %s' % \ + (current_process().name, func.__name__, args, result) + +# +# Functions referenced by tasks +# + +def mul(a, b): + time.sleep(0.5*random.random()) + return a * b + +def plus(a, b): + time.sleep(0.5*random.random()) + return a + b + +# +# +# + +def test(): + NUMBER_OF_PROCESSES = 4 + TASKS1 = [(mul, (i, 7)) for i in range(20)] + TASKS2 = [(plus, (i, 8)) for i in range(10)] + + # Create queues + task_queue = Queue() + done_queue = Queue() + + # Submit tasks + for task in TASKS1: + task_queue.put(task) + + # Start worker processes + for i in range(NUMBER_OF_PROCESSES): + Process(target=worker, args=(task_queue, done_queue)).start() + + # Get and print results + print 'Unordered results:' + for i in range(len(TASKS1)): + print '\t', done_queue.get() + + # Add more tasks using `put()` + for task in TASKS2: + task_queue.put(task) + + # Get and print some more results + for i in range(len(TASKS2)): + print '\t', done_queue.get() + + # Tell child processes to stop + for i in range(NUMBER_OF_PROCESSES): + task_queue.put('STOP') + + +if __name__ == '__main__': + freeze_support() + test()