进程_锁

#进程同步：加锁（串行）-----不建议使用，因为考虑到要释放锁
from multiprocessing import Process,Lock
import time

def work(lock):
    lock.acquire()
    print("target %s is running" %os.getpid())
    time.sleep(2)
    print("target %s is done" %os.getpid())
    lock.release()
if __name__=="__main__":
    lock=Lock()
    for i in range(3):
        p=Process(target=work,args=(lock,))
        p.start()
    print("主进程")
'''
target 10879 is running
主进程
target 10879 is done
target 10880 is running
target 10880 is done
target 10883 is running
target 10883 is done

'''

#共享数据，硬盘（文件），Lock --不推荐
from multiprocessing import Process,Lock
import time,json,random
import os
def search():
    dic=json.load(open('db.txt'))
    print('%s 剩余票数 %s ' %(os.getpid(),dic['count']))

def get():
    dic=json.load(open('db.txt'))
    time.sleep(0.1) #模拟读数据的网络延迟
    if dic['count'] >0:
        dic['count']-=1
        time.sleep(0.2) #模拟写数据的网络延迟
        json.dump(dic,open('db.txt','w'))
        print('%s 购票成功'%os.getpid())

def task(lock):
    search()
    lock.acquire()
    get()
    lock.release()
if __name__ == '__main__':
    lock=Lock()
    for i in range(10): #模拟并发100个客户端抢票
        p=Process(target=task,args=(lock,))
        p.start()

#共享数据，内存 Manager，Lock  --不推荐
from multiprocessing import Process,Manager,Lock

# def task(dic,lock):
#     lock.acquire()
#     dic["count"]-=1
#     lock.release()
    
def task(dic,lock):
    with lock:
        dic["count"]-=1
    

if __name__=="__main__":
    lock=Lock()
    m=Manager()
    dict=m.dict({"count":100})
    p_list=[]
    for i in range(100):
        p=Process(target=task,args=(dict,lock))
        p_list.append(p)
        p.start()
    for p in p_list:
        p.join()
    print(dict)