python多线程的适用场景

1.多线程对于计算密集型无用

需求:列表li1每个元素加1,列表li2每个元素加100
# 导入模块
import threading

li1 = [11, 22, 33]  # +1
li2 = [44, 55, 66]  # 100

def func(data, plus):
    for i in range(len(data)):
        data[i] = data[i] + plus

# 线程1：负责给li1每个元素加1
t1 = threading.Thread(target=func, args=(li1, 1))
t1.start()

# 线程2：负责给li2每个元素加100
t2 = threading.Thread(target=func, args=(li2, 100))
t2.start()

2.多线程对于IO操作有用

# 导入模块
import threading
import uuid
import requests

# 图片地址列表
url_list = [
    'https://www3.autoimg.cn/newsdfs/g28/M05/F9/98/120x90_0_autohomecar__ChsEnluQmUmARAhAAAFES6mpmTM281.jpg',
    'https://www2.autoimg.cn/newsdfs/g28/M09/FC/06/120x90_0_autohomecar__ChcCR1uQlD6AT4P3AAGRMJX7834274.jpg',
    'https://www2.autoimg.cn/newsdfs/g3/M00/C6/A9/120x90_0_autohomecar__ChsEkVuPsdqAQz3zAAEYvWuAspI061.jpg',
]

def task(img_url):
    ret = requests.get(img_url)
    file_name = str(uuid.uuid4()) + '.jpg'
    with open(file_name, mode='wb') as f:
        f.write(ret.content)

for url in url_list:
    t = threading.Thread(target=task, args=(url,))
    t.start()