91 lines
2.0 KiB
Python
91 lines
2.0 KiB
Python
#
|
|
# 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).
|
|
#
|
|
# Copyright (c) 2006-2008, R Oudkerk
|
|
# All rights reserved.
|
|
#
|
|
|
|
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()
|