Python的进程锁，进程队列

import json,time,random

# 1.读写数据库当中的票数
def wr_info(sign , dic=None):
    if sign == "r":
        with open("ticket",mode="r",encoding="utf-8") as fp:
            dic = json.load(fp)
        return dic
        
    elif sign == "w":
        with open("ticket",mode="w",encoding="utf-8") as fp:
            json.dump(dic,fp)

# dic = wr_info("w",dic={"count":0})
# print(dic , type(dic) )

# 2.执行抢票的方法
def get_ticket(person):
    # 先获取数据库中实际票数
    dic = wr_info("r")
    
    # 模拟一下网络延迟
    time.sleep(random.uniform(0.1,0.7))
    
    # 判断票数
    if dic["count"] > 0:
        print("{}抢到票了".format(person))
        # 抢到票后,让当前票数减1
        dic["count"] -= 1
        # 更新数据库中的票数
        wr_info("w",dic)
    else:
        print("{}没有抢到票哦".format(person))
        
# 3.对抢票和读写票数做一个统一的调用
def main(person,lock):
    
    # 查看剩余票数
    dic = wr_info("r")
    print("{}查看票数剩余: {}".format(person,dic["count"]))
    
    # 上锁
    lock.acquire()
    # 开始抢票
    get_ticket(person)
    # 解锁 
    lock.release()
    
if __name__ == "__main__":
    lock = Lock()
    lst = ["梁新宇","康裕康","张保张","于朝志","薛宇健","韩瑞瑞","假摔先","刘子涛","黎明辉","赵凤勇"]
    for i in lst:
        p = Process(    target=main,args=(  i  , lock  )   )
        p.start()
    

from multiprocessing import Semaphore , Process
import time , random

    # 同一时间允许多个进程上5把锁
    sem = Semaphore(5)
    #上锁
    sem.acquire()
    print("执行操作 ... ")
    #解锁
    sem.release()


def singsong_ktv(person,sem):
    # 上锁
    sem.acquire()
    
    print("{}进入了唱吧ktv , 正在唱歌 ~".format(person))
    # 唱一段时间
    time.sleep( random.randrange(4,8) ) # 4 5 6 7
    
    print("{}离开了唱吧ktv , 唱完了 ... ".format(person))
    
    # 解锁
    sem.release()

if __name__ == "__main__":
    sem = Semaphore(5)
    lst = ["赵凤勇" , "沈思雨", "赵万里" , "张宇" , "假率先" , "孙杰龙" , "陈璐" , "王雨涵" , "杨元涛" , "刘一凤"   ]
    for i  in lst:
        p = Process(target=singsong_ktv , args = (i , sem)        )
        p.start()

try:
    print(  q.get_nowait()  )
    print(  q.get_nowait()  )
    print(  q.get_nowait()  )
    print(  q.get_nowait()  )
except : #queue.Empty
    pass


# put_nowait() 非阻塞版本的put
# 设置当前队列最大长度为3 ( 元素个数最多是3个 )
"""在指定队列长度的情况下,如果塞入过多的数据,会导致阻塞"""
# q2 = Queue(3)
# q2.put(111)
# q2.put(222)
# q2.put(333)
# q2.put(444)

q2 = Queue(3)
try:
    q2.put_nowait(111)
    q2.put_nowait(222)
    q2.put_nowait(333)
    q2.put_nowait(444)
except:
    pass

# put() 存放
# get() 获取
# get_nowait() 拿不到报异常
# put_nowait() 非阻塞版本的put
q.empty()      检测是否为空  (了解)
q.full()        检测是否已经存满 (了解)
q.qsize()     检测队列元素个数(了解)

def func(q):
    # 2.子进程获取主进程存放的数据
    res = q.get()
    print(res,"<22>")
    # 3.子进程中存放数据
    q.put("刘一缝")

if __name__ == "__main__":
    q3 = Queue()
    p = Process(target=func,args=(q3,))
    p.start()

    # 1.主进程存入数据
    q3.put("赵凤勇")
    
    # 为了等待子进程把数据存放队列后,主进程在获取数据;
    p.join()
    
    # 4.主进程获取子进程存放的数据
    print(q3.get() , "<33>")