进程和线程

Posted 2022-07-16 dorami

线程池

import threadpool
import threading
import requests
import hashlib

def down_load_file(url):
    r = requests.get(url)
    m = hashlib.md5(url.encode())
    print(‘正在下载====%s‘%m.hexdigest())
    with open(‘%s.jpg‘%m.hexdigest(),‘wb‘) as fw:
        fw.write(r.content)


url_list = [‘http://www.nnzhp.cn/wp-content/uploads/2019/02/jiami.jpeg‘,
            ‘http://www.nnzhp.cn/wp-content/uploads/2019/03/js.png‘,
            ‘http://www.nnzhp.cn/wp-content/uploads/2018/08/ab389f04cb5b57344ef9655428bccaec.png‘
            ]
pool = threadpool.ThreadPool(10)#创建一个线程池，指定线程池最多有多少个线程

reqs = threadpool.makeRequests(down_load_file,url_list) #调用生成启动线程用的参数

# for req in reqs:
#     pool.putRequest(req)

[pool.putRequest(req) for req in reqs]

print(‘当前的线程数‘,threading.activeCount())

pool.wait() #等待

print(‘测试结束‘)

守护线程

import time,threading,os
import threadpool

count = 0
lock = threading.Lock() #申请一把锁

def lajfenlei():
    global count

    # lock.acquire()
    # count += 1
    # lock.release()
    with lock:
        count+=1
    print(‘干垃圾‘)

for i in range(10):
    syy = threading.Thread(target=lajfenlei,)
    # syy.setDaemon(True) #把子线程设置成守护线程
    syy.start()
while threading.activeCount() != 1:
    pass

print(count)
print(‘完成！‘)


#8
#python GIL 全局解释器锁，导致python的多线程利用不了多核cpu，但是多进程可以。

#锁

多进程

import multiprocessing
import time
import threading

def say():
    time.sleep(2)
    print(‘hhhh‘)

def lajfenlei():
    for i in range(10):
        t = threading.Thread(target=say)
        t.start()
    print(threading.activeCount())
    print(‘垃圾分类‘)

if __name__ == ‘__main__‘:
    for i in range(5):
        p = multiprocessing.Process(target=lajfenlei)
        p.start()
        print(p.pid )

    while len(multiprocessing.active_children())!=0:#等待子进程执行完成
        pass

    print(‘子进程都运行完了。‘)

多线程

import threading
import requests,time

def lajfenlei():
    time.sleep(2)
    print(‘干垃圾‘)

# start_time = time.time()
# for i in range(10):
#     lajfenlei()
# print( time.time() - start_time)

def shangke():
    print(‘上课‘)

start_time = time.time()


#第一种方法，主线程等待子线程
# threads =[]
#
# for i in range(10):
#     syy = threading.Thread(target=lajfenlei,)
#     syy.start()
#     threads.append(syy)
#
# for t in threads:
#     t.join()

for i in range(10):
    syy = threading.Thread(target=lajfenlei,)
    syy.start()

while True:
    if threading.activeCount()==1:
        break

end_time = time.time()

print(end_time - start_time)