python之路——38

Posted 2021-11-30 wan2-0

复习

1.多进程
    1.方法
        进程对象.start()    开启一个进程
        进程对象.join()    感知一个进程的结束
        进程对象.terminate()    结束一个进程
        进程对象.is_alive()    查看某个进程是否存在
    2.属性
        进程对象.name   进程名
        进程对象.pid    进程号
        进程对象.daemon    值为True，新的子进程为守护进程
                           随着主进程代码执行的结束而结束
                           start之前设置

学习内容

见代码区

代码区

1.子进程中不能有input操作

from multiprocessing import Process

def func():
    num = input(‘>>> ‘)
    print(num)


if __name__ == ‘__main__‘:
    Process(target=func).start()

2.进程同步控制——信号量 （多个锁）

from multiprocessing import Process
from multiprocessing import Semaphore
import time
import random


def ktv(i,sem):
    sem.acquire()
    print(‘%s走进ktv‘%i)
    time.sleep(random.randint(5,10))
    print(‘%s走出ktv‘%i)
    sem.release()

if __name__ == ‘__main__‘:
    sem = Semaphore(4)
    for i in range(20):
        p = Process(target=ktv,args=(i,sem))
        p.start()

3.事件——一个信号控制多个进程同时执行或阻塞   红绿灯

from multiprocessing import Process
from  multiprocessing import Event
import time,random

def cars(i,e):
    if not e.is_set():
        print(‘车辆%s在等待 ‘%i)
        e.wait()
    print(‘车辆%s通过 ‘%i)



def traffic_light(e):
    while 1:
        if e.is_set():
            e.clear()
            print(‘\033[31m红灯亮了\033[0m‘)
        else:
            e.set()
            print(‘\033[32m绿灯亮了\033[0m‘)
        time.sleep(2)


if __name__ == ‘__main__‘:
    e = Event()
    traffic = Process(target=traffic_light,args=(e,))
    traffic.start()
    for i in range(20):
        car = Process(target=cars, args=(i,e))
        car.start()
        time.sleep(random.randint(1,3))

4.队列

from multiprocessing import Process,Queue
def produce(q):
    q.put(‘from func-produce‘)
def consume(q):
    print(q.get())
if __name__ == ‘__main__‘:
    q = Queue()
    p = Process(target=produce,args=(q,))
    p.start()
    c = Process(target=consume,args=(q,))
    c.start()

5.消费者，生产者模型——joinablequeue

from multiprocessing import Process,JoinableQueue
import time,random
def producer(name,food,q):
    for i in range(5):
        time.sleep(random.randint(1,2))
        f = ‘%s生产了%s%s‘%(name,food,i)
        print(f)
        q.put(f)
    q.join()

def consumer(name,q):
    while 1:
        c = q.get()
        if c == None:
            print(‘%s 得到一个None‘%name)
            break
        print(‘\033[31m%s消费了%s\033[0m‘%(name,c))
        time.sleep(random.randint(1,2))
        q.task_done()
if __name__ == ‘__main__‘:
    q = JoinableQueue()
    p1 = Process(target=producer,args=(‘alex‘,‘包子‘,q))
    p2 = Process(target=producer,args=(‘egon‘,‘馒头‘,q))
    p1.start()
    p2.start()
    c1 = Process(target=consumer,args=(‘小明‘,q))
    c2 = Process(target=consumer,args=(‘小华‘,q))
    c1.daemon = True
    c2.daemon = True
    c1.start()
    c2.start()
    p1.join()
    p2.join()