什么是进程(process)?什么是线程？

import timeimport requestsdef get_res():

    urls = ['','','','']

    start = time.time()for url in urls:print(url)

        resp = requests.get(url)print(resp)

    end = time.time()print('单线程运行时间:', end - start)

http://www.baidu.com<Response [200]>https://www.taobao.com/

<Response [200]>https://www.jd.com/

<Response [200]>http://www.meilishuo.com/

<Response [200]>单线程运行时间: 1.0470597743988037

import timeimport threadingdef run(count):#每次执行该方法，需要休息2stime.sleep(2)print(count)#开始创建多线程start = time.time()for i in range(5):#创建线程，指定运行哪个函数，也就是指定哪个函数运行需要创建多线程#target=要运行的函数名# args=函数运行传入的参数，run方法需要传入count，把创建th = threading.Thread(target=run, args=(i, ))#启动线程    th.start()#多线程创建完毕且运行结束end = time.time()print('运行时间：', end - start)

运行时间： 0.0

104

2

3

import timeimport threadingdef run(count):#每次执行该方法，需要休息2stime.sleep(2)print(count)#开始创建多线程start = time.time()#存放创建的所有线程threads_list = []for i in range(5):#创建线程，指定运行哪个函数，也就是指定哪个函数运行需要创建多线程#target=要运行的函数名# args=函数运行传入的参数，run方法需要传入count，把创建th = threading.Thread(target=run, args=(i, ))#启动线程    th.start()#把启动的每一个线程添加到线程组内    threads_list.append(th)for t in threads_list:#主线程循环等待每个子线程运行完毕， t代表每个子线程t.join()  #等待线程结束#多线程创建完毕且运行结束end = time.time()print('运行时间：', end - start)

01

2

4

3运行时间： 2.0011146068573

import threadingimport timedef run(count):

    time.sleep(2)print(count)for i in range(5):#循环创建线程，总共5个线程t = threading.Thread(target=run, args=(i, ))#设置守护线程,新创建的这些线程都是 主线程的 守护线程， 主线程创建一个线程后 就运行结束了    t.setDaemon(True)#启动线程，守护线程设置必须在start前面    t.start()print('over')

import threadingfrom threading import Lock#创建lock对象num = 0

lock = Lock()   #申请一把锁,创建锁的对象def run2():global num

    lock.acquire()      #修改数据前 加锁num += 1lock.release()      #修改后释放解锁lis = []for i in range(5):#创建线程t = threading.Thread(target=run2)#启动线程    t.start()#将启动的线程添加到线程组内    lis.append(t)for t in lis:#等待线程运行结束    t.join()#num的值为5，执行多次后，会出现不一样的值print('over', num)

import threading,timedef run1():print("grab the first part data")

    lock.acquire()global num

    num +=1lock.release()return numdef run2():print("grab the second part data")

    lock.acquire()global  num2

    num2+=1lock.release()return num2def run3():

    lock.acquire()

    res = run1()print('--------between run1 and run2-----')

    res2 = run2()

    lock.release()print(res,res2)if __name__ == '__main__':

    num,num2 = 0,0

    lock = threading.RLock()  # 声明递归锁# lock = threading.Lock() # 用互斥锁，会锁死了，弄混锁情况，可以试一下for i in range(10):

        t = threading.Thread(target=run3)

        t.start()while threading.active_count() != 1:print(threading.active_count())else:print('----all threads done---')print(num,num2)

import threadingimport timeclass MyThread(threading.Thread):def __init__(self, num):

        threading.Thread.__init__(self)

        self.num = numdef run(self):  # 定义每个线程要运行的函数print("running on number:%s" % self.num)

        time.sleep(3)if __name__ == '__main__':

    t1 = MyThread(1)

    t2 = MyThread(2)

    t1.start()

    t2.start()

from multiprocessing import Processdef f(name):

    time.sleep(2)print('hello', name)if __name__ == '__main__':for i in range(10):

        p = Process(target=f, args=('niu',))

        p.start()