پاسخ تمرینات آموزش ماژول Multiprocessing – کلاس Lock

import multiprocessing

lock = multiprocessing.Lock()
shared_counter = multiprocessing.Value('i', 0)

def increment_counter(shared_counter, lock):
    with lock:
        for _ in range(100000):
            shared_counter.value += 1

if __name__ == '__main__':
    processes = [multiprocessing.Process(target=increment_counter, args=(shared_counter, lock))
                 for _ in range(5)]
    for p in processes: p.start()
    for p in processes: p.join()
    print("Final value:", shared_counter.value)   # 500000

import multiprocessing

lock = multiprocessing.Lock()
shared_counter = multiprocessing.Value('i', 0)

def increment_counter(shared_counter, lock):
    with lock:
        for _ in range(100000):
            shared_counter.value += 1

if __name__ == '__main__':
    processes = [multiprocessing.Process(target=increment_counter, args=(shared_counter, lock))
                 for _ in range(5)]
    for p in processes: p.start()
    for p in processes: p.join()
    print("Final value:", shared_counter.value)   # 500000

import multiprocessing

shared_counter = multiprocessing.Value('i', 0)

def increment_counter(shared_counter):
    with shared_counter.get_lock():        # Value's built-in lock
        for _ in range(100000):
            shared_counter.value += 1

if __name__ == '__main__':
    processes = [multiprocessing.Process(target=increment_counter, args=(shared_counter,))
                 for _ in range(5)]
    for p in processes: p.start()
    for p in processes: p.join()
    print("Final value:", shared_counter.value)   # 500000

import multiprocessing

shared_counter = multiprocessing.Value('i', 0)

def increment_counter(shared_counter):
    with shared_counter.get_lock():        # Value's built-in lock
        for _ in range(100000):
            shared_counter.value += 1

if __name__ == '__main__':
    processes = [multiprocessing.Process(target=increment_counter, args=(shared_counter,))
                 for _ in range(5)]
    for p in processes: p.start()
    for p in processes: p.join()
    print("Final value:", shared_counter.value)   # 500000

import multiprocessing

def worker(chunk, success_count, lock):
    local = sum(1 for x in chunk if x % 2 == 0)   # heavy work OUTSIDE the lock
    with lock:
        success_count.value += local               # only the shared update is locked

if __name__ == '__main__':
    lock = multiprocessing.Lock()
    success_count = multiprocessing.Value('i', 0)
    data = list(range(100))
    chunks = [data[i::4] for i in range(4)]

    procs = [multiprocessing.Process(target=worker, args=(c, success_count, lock)) for c in chunks]
    for p in procs: p.start()
    for p in procs: p.join()
    print("total evens found:", success_count.value)   # 50

import multiprocessing

def worker(chunk, success_count, lock):
    local = sum(1 for x in chunk if x % 2 == 0)   # heavy work OUTSIDE the lock
    with lock:
        success_count.value += local               # only the shared update is locked

if __name__ == '__main__':
    lock = multiprocessing.Lock()
    success_count = multiprocessing.Value('i', 0)
    data = list(range(100))
    chunks = [data[i::4] for i in range(4)]

    procs = [multiprocessing.Process(target=worker, args=(c, success_count, lock)) for c in chunks]
    for p in procs: p.start()
    for p in procs: p.join()
    print("total evens found:", success_count.value)   # 50