python学习—Day41—多进程锁与多进程共享内存

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多进程锁：

需求：

一个进程写入一个文件，一个进程追加文件，一个进程读文件，同时启动起来

我们可以通过join()方法实现，这里为了学习Lock，用lock实现。

先看不加锁程序，再看加锁程序，对比两者的区别。

#@File :jinchenglock.pyimport multiprocessingimport timelock = multiprocessing.Lock()lock.acquire()                        #获得锁lock.release()                        #释放锁.这两者可以直接使用with lock一句实现#不加锁# number  +1# number  +3def add(number, value, lock):    # with lock:        print("init add{0} number = {1}".format(value, number))        for i in xrange(1, 6):            number += value            time.sleep(1)            print("add{0} number = {1}".format(value, number))if __name__ == "__main__":    lock = multiprocessing.Lock()    number = 0    p1 = multiprocessing.Process(target=add, args=(number, 1, lock))    p2 = multiprocessing.Process(target=add, args=(number, 3, lock))    p1.start()    p2.start()    print ("main end")

main end
init add1 number = 0
init add3 number = 0
add1 number = 1
add3 number = 3
add1 number = 2
add3 number = 6
add1 number = 3
add3 number = 9
add1 number = 4
add3 number = 12
add1 number = 5
add3 number = 15

使用锁：

#@File :jinchenglock.pyimport multiprocessingimport timelock = multiprocessing.Lock()lock.acquire()                        #获得锁lock.release()                        #释放锁.这两者可以直接使用with lock一句实现#不加锁# number  +1# number  +3def add(number, value, lock):    with lock:        print("init add{0} number = {1}".format(value, number))        for i in xrange(1, 6):            number += value            time.sleep(1)            print("add{0} number = {1}".format(value, number))if __name__ == "__main__":    lock = multiprocessing.Lock()    number = 0    p1 = multiprocessing.Process(target=add, args=(number, 1, lock))    p2 = multiprocessing.Process(target=add, args=(number, 3, lock))    p1.start()    p2.start()    print ("main end")

main end
init add1 number = 0
add1 number = 1
add1 number = 2
add1 number = 3
add1 number = 4
add1 number = 5
init add3 number = 0
add3 number = 3
add3 number = 6
add3 number = 9
add3 number = 12
add3 number = 15

#@File :jinchenglock.pyimport multiprocessingimport timelock = multiprocessing.Lock()lock.acquire()                        #获得锁lock.release()                        #释放锁.这两者可以直接使用with lock一句实现#不加锁# number  +1# number  +3def add(number, value, lock):    lock.acquire()    try:        print("init add{0} number = {1}".format(value, number))        for i in xrange(1, 6):            number += value            time.sleep(1)            print("add{0} number = {1}".format(value, number))    except Exception as e:        raise e    finally:        lock.release()if __name__ == "__main__":    lock = multiprocessing.Lock()    number = 0    p1 = multiprocessing.Process(target=add, args=(number, 1, lock))    p2 = multiprocessing.Process(target=add, args=(number, 3, lock))    p1.start()    p2.start()    print ("main end")

多进程共享内存：

#@File :jinchenglock.pyimport multiprocessingimport timedef add(number, add_value):    try:        print("init add{0} number = {1}".format(add_value, number.value))        for i in xrange(1, 6):            number.value += add_value            print("###############  add{0} has added ########### ".format(add_value))            time.sleep(1)            print("add{0} number = {1}".format(add_value, number.value))    except Exception as e:        raise eif __name__ == "__main__":    number = multiprocessing.Value('i', 0)    p1 = multiprocessing.Process(target=add, args=(number, 1))    p2 = multiprocessing.Process(target=add, args=(number, 3))    p1.start()    p2.start()    print ("main end")

main end
init add1 number = 0
############### add1 has added ###########
init add3 number = 1
############### add3 has added ###########
add1 number = 4
############### add1 has added ###########
add3 number = 5
############### add3 has added ###########
add1 number = 8
############### add1 has added ###########
add3 number = 9
############### add3 has added ###########
add1 number = 12
############### add1 has added ###########
add3 number = 13
############### add3 has added ###########
add1 number = 16
add3 number = 16
############### add1 has added ###########
############### add3 has added ###########
add1 number = 20
add3 number = 20

#@File :jinchenglock.pyimport multiprocessingimport time# Value()   数值# Array()   数组def add(number, add_value, lock):    lock.acquire()    try:        print("init add{0} number = {1}".format(add_value, number.value))        for i in xrange(1, 6):            number.value += add_value            print("###############  add{0} has added ########### ".format(add_value))            time.sleep(1)            print("add{0} number = {1}".format(add_value, number.value))    except Exception as e:        raise e    finally:        lock.release()def change(arr):    for i in range(len(arr)):        arr[i] = -arr[i]if __name__ == "__main__":    lock = multiprocessing.Lock()    number = multiprocessing.Value('i', 0)    arr = multiprocessing.Array('i', range(10))    p1 = multiprocessing.Process(target=add, args=(number, 1, lock))    p2 = multiprocessing.Process(target=add, args=(number, 3, lock))    p3 = multiprocessing.Process(target=change, args=(arr, ))    p1.start()    p2.start()    p3.start()    p3.join()    print(arr[:])    print ("main end")

init add1 number = 0
############### add1 has added ###########
[0, -1, -2, -3, -4, -5, -6, -7, -8, -9]
main end
add1 number = 1
############### add1 has added ###########
add1 number = 2
############### add1 has added ###########
add1 number = 3
############### add1 has added ###########
add1 number = 4
############### add1 has added ###########
add1 number = 5
init add3 number = 5
############### add3 has added ###########
add3 number = 8
############### add3 has added ###########
add3 number = 11
############### add3 has added ###########
add3 number = 14
############### add3 has added ###########
add3 number = 17
############### add3 has added ###########
add3 number = 20

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