cpython/Doc/includes/mp_synchronize.py

#
# A test file for the `multiprocessing` package
#
# Copyright (c) 2006-2008, R Oudkerk
# All rights reserved.
#

import time
import sys
import random
from queue import Empty

import multiprocessing               # may get overwritten


#### TEST_VALUE

def value_func(running, mutex):
    random.seed()
    time.sleep(random.random()*4)

    mutex.acquire()
    print('\n\t\t\t' + str(multiprocessing.current_process()) + ' has finished')
    running.value -= 1
    mutex.release()

def test_value():
    TASKS = 10
    running = multiprocessing.Value('i', TASKS)
    mutex = multiprocessing.Lock()

    for i in range(TASKS):
        p = multiprocessing.Process(target=value_func, args=(running, mutex))
        p.start()

    while running.value > 0:
        time.sleep(0.08)
        mutex.acquire()
        print(running.value, end=' ')
        sys.stdout.flush()
        mutex.release()

    print()
    print('No more running processes')


#### TEST_QUEUE

def queue_func(queue):
    for i in range(30):
        time.sleep(0.5 * random.random())
        queue.put(i*i)
    queue.put('STOP')

def test_queue():
    q = multiprocessing.Queue()

    p = multiprocessing.Process(target=queue_func, args=(q,))
    p.start()

    o = None
    while o != 'STOP':
        try:
            o = q.get(timeout=0.3)
            print(o, end=' ')
            sys.stdout.flush()
        except Empty:
            print('TIMEOUT')

    print()


#### TEST_CONDITION

def condition_func(cond):
    cond.acquire()
    print('\t' + str(cond))
    time.sleep(2)
    print('\tchild is notifying')
    print('\t' + str(cond))
    cond.notify()
    cond.release()

def test_condition():
    cond = multiprocessing.Condition()

    p = multiprocessing.Process(target=condition_func, args=(cond,))
    print(cond)

    cond.acquire()
    print(cond)
    cond.acquire()
    print(cond)

    p.start()

    print('main is waiting')
    cond.wait()
    print('main has woken up')

    print(cond)
    cond.release()
    print(cond)
    cond.release()

    p.join()
    print(cond)


#### TEST_SEMAPHORE

def semaphore_func(sema, mutex, running):
    sema.acquire()

    mutex.acquire()
    running.value += 1
    print(running.value, 'tasks are running')
    mutex.release()

    random.seed()
    time.sleep(random.random()*2)

    mutex.acquire()
    running.value -= 1
    print('%s has finished' % multiprocessing.current_process())
    mutex.release()

    sema.release()

def test_semaphore():
    sema = multiprocessing.Semaphore(3)
    mutex = multiprocessing.RLock()
    running = multiprocessing.Value('i', 0)

    processes = [
        multiprocessing.Process(target=semaphore_func,
                                args=(sema, mutex, running))
        for i in range(10)
        ]

    for p in processes:
        p.start()

    for p in processes:
        p.join()


#### TEST_JOIN_TIMEOUT

def join_timeout_func():
    print('\tchild sleeping')
    time.sleep(5.5)
    print('\n\tchild terminating')

def test_join_timeout():
    p = multiprocessing.Process(target=join_timeout_func)
    p.start()

    print('waiting for process to finish')

    while 1:
        p.join(timeout=1)
        if not p.is_alive():
            break
        print('.', end=' ')
        sys.stdout.flush()


#### TEST_EVENT

def event_func(event):
    print('\t%r is waiting' % multiprocessing.current_process())
    event.wait()
    print('\t%r has woken up' % multiprocessing.current_process())

def test_event():
    event = multiprocessing.Event()

    processes = [multiprocessing.Process(target=event_func, args=(event,))
                 for i in range(5)]

    for p in processes:
        p.start()

    print('main is sleeping')
    time.sleep(2)

    print('main is setting event')
    event.set()

    for p in processes:
        p.join()


#### TEST_SHAREDVALUES

def sharedvalues_func(values, arrays, shared_values, shared_arrays):
    for i in range(len(values)):
        v = values[i][1]
        sv = shared_values[i].value
        assert v == sv

    for i in range(len(values)):
        a = arrays[i][1]
        sa = list(shared_arrays[i][:])
        assert a == sa

    print('Tests passed')

def test_sharedvalues():
    values = [
        ('i', 10),
        ('h', -2),
        ('d', 1.25)
        ]
    arrays = [
        ('i', list(range(100))),
        ('d', [0.25 * i for i in range(100)]),
        ('H', list(range(1000)))
        ]

    shared_values = [multiprocessing.Value(id, v) for id, v in values]
    shared_arrays = [multiprocessing.Array(id, a) for id, a in arrays]

    p = multiprocessing.Process(
        target=sharedvalues_func,
        args=(values, arrays, shared_values, shared_arrays)
        )
    p.start()
    p.join()

    assert p.exitcode == 0


####

def test(namespace=multiprocessing):
    global multiprocessing

    multiprocessing = namespace

    for func in [test_value, test_queue, test_condition,
                 test_semaphore, test_join_timeout, test_event,
                 test_sharedvalues]:

        print('\n\t######## %s\n' % func.__name__)
        func()

    ignore = multiprocessing.active_children()      # cleanup any old processes
    if hasattr(multiprocessing, '_debug_info'):
        info = multiprocessing._debug_info()
        if info:
            print(info)
            raise ValueError('there should be no positive refcounts left')


if __name__ == '__main__':
    multiprocessing.freeze_support()

    assert len(sys.argv) in (1, 2)

    if len(sys.argv) == 1 or sys.argv[1] == 'processes':
        print(' Using processes '.center(79, '-'))
        namespace = multiprocessing
    elif sys.argv[1] == 'manager':
        print(' Using processes and a manager '.center(79, '-'))
        namespace = multiprocessing.Manager()
        namespace.Process = multiprocessing.Process
        namespace.current_process = multiprocessing.current_process
        namespace.active_children = multiprocessing.active_children
    elif sys.argv[1] == 'threads':
        print(' Using threads '.center(79, '-'))
        import multiprocessing.dummy as namespace
    else:
        print('Usage:\n\t%s [processes | manager | threads]' % sys.argv[0])
        raise SystemExit(2)

    test(namespace)