single_multi_thread.py

import threading
import time
import requests

urls = [f"https://www.cnblogs.com/#p{page}" for page in range(1, 50+1)]

def craw(url):
 r = requests.get(url)
 print(url, r.text)


def single_thread():
 print('single thread begin')
 for url in urls:
 craw(url)
 print('single thread end')

def multi_thread():
 print('muiti thread begin')
 threads = []
 for url in urls:
 threads.append(
 threading.Thread(target=craw, args=(url,)) # 注意这里参数是一个元组，需要加逗号。否则识别为字符串
 )

 for thread in threads:
 thread.start() # 启动线程

 for thread in threads:
 thread.join() # 默认情况下，主线程会创建多个子线程，且互不干涉。如果希望主线程等待子线程完成后，在执行后续操作。需要使用join，将其阻塞。
 print('muiti thread end')

if __name__ == "__main__":
 start = time.time()
 single_thread()
 end = time.time()
 print('single thread cost', end - start, 'seconds') # 耗时12.030196905136108 seconds

 start = time.time()
 multi_thread()
 end = time.time()
 print('multi thread cost', end - start, 'seconds') # 耗时0.47228384017944336 seconds