7/13/2021python 核心编程02-02-15

生产者与消费者的解耦问题：

耦合时代码之前联系性很强，不好

解耦： 减少之间的联系

所以第一版本就要想的长远一点 

这个例子使用队列作为缓冲部分

#encoding=utf-8
import threading
import time
from queue import Queue

class Producer(threading.Thread):
    def run(self):
        global queue
        count = 0
        while True:
            if queue.qsize()<1000:
                count = count +1
                msg = '生产产品'+str(count)
                queue.put(msg)
                print(msg)
            time.sleep(1)

class Consumer(threading.Thread):
    def run(self):
        global queue
        count = 0
        while True:
            if queue.qsize()>100:
                for i in range(3):
                    msg = self.name +'消费了'+queue.get()
                    print(msg)
            time.sleep(1)

if __name__ == "__main__":
    queue = Queue()
    for i in range(500):
        queue.put("初始产品"+str(i))
    for i in range(2):
        p = Producer()
        p.start()
    for i in range(5):
        c = Consumer()
        c.start()
ThreadLocal在线程中的应用
这是一个特殊的全局变量，多线程访问可以独自使用不会对其它线程有影响
一般来说，全局变量是共享的对于多线程

import threading

#创建全局threadlocal对象
local_school = threading.local()

def process_student():
    #获取当前线程关联的student：
    std = local_school.student
    print("hello, %s (in %s)"%(std, threading.current_thread().name))

def process_thread(name):
    #绑定threadlocal的student
    local_school.student = name #注意。可以增添一个属性
    process_student()

t1 = threading.Thread(target= process_thread, args=('dongge',), name='Thread-A')
t2 = threading.Thread(target= process_thread, args=('laowang',), name='Thread-B')
t1.start()
t2.start()
t1.join()
t2.join()
Result：

hello, dongge (in Thread-A)
hello, laowang (in Thread-B)