python学习—Day41—多进程锁与多进程共享内存

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.py
import multiprocessing

import time

lock = 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  +3
def 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.py
import multiprocessing

import time

lock = 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  +3
def 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.py
import multiprocessing
import time

lock = 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  +3
def 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")

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

多进程共享内存：

#@File :jinchenglock.py
import multiprocessing
import time

def 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 e
if __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.py
import multiprocessing
import 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