python异步处理请求_Python 异步请求
1. 正常下载漫画，requests 阻塞式。
import requests, bs4, time
import asyncio, aiohttp
def get_image_urls(url):
res = requests.get(url)
res.raise_for_status()
soup = bs4.BeautifulSoup(res.text, 'lxml')
imgs = soup.select('div.list img')
for img in imgs:
yield img.get('data-kksrc')
def download_image(image_url, filename):
res = requests.get(image_url)
res.raise_for_status()
image = res.content
with open(r'e:\path\mh\{}.jpg'.format(filename), 'wb') as fp:
fp.write(image)
if __name__ == '__main__':
site_url = 'https://www.kuaikanmanhua.com/web/comic/105372/'
t_url = 'https://www.kuaikanmanhua.com/web/comic/15559/'
image_urls = [image_url for image_url in get_image_urls(site_url)]
t_list = [image_url for image_url in get_image_urls(t_url)]
image_urls.extend(t_list)
start = time.time()
for filename, url in enumerate(image_urls, start=1):
download_image(url, filename)
print('总计：{:.2f}s'.format(time.time()-start))
2. 异步包 asyncio 基本用法
import asyncio
import time
async def asynct():
print('asyncio...')
await asyncio.sleep(1)
def main():
start = time.time()
loop = asyncio.get_event_loop()
tasks = [asynct() for i in range(10)]
tasks_wait = asyncio.wait(tasks)
loop.run_until_complete(tasks_wait)
loop.close()
print('total: {:.2f}s'.format(time.time()-start))
if __name__ == '__main__':
main()
结果：
asyncio...
asyncio...
asyncio...
asyncio...
asyncio...
asyncio...
asyncio...
asyncio...
asyncio...
asyncio...
total: 1.01s
asyncio.sleep(1) 并不会阻塞运行，而是返回主线程继续运行，所以不会等待 10s 时间。
3. 异步下载漫画
import asyncio, aiohttp
import requests, bs4
import time
import tqdm
import concurrent.futures as futures
async def download_images(url, filename):
async with aiohttp.ClientSession() as session:
async with session.get(url) as res:
image = await res.content.read()
with open(r'e:\path\mh\{}.jpg'.format(filename), 'wb') as fp:
fp.write(image)
def test():
site_url = 'https://www.kuaikanmanhua.com/web/comic/105372/'
t_url = 'https://www.kuaikanmanhua.com/web/comic/15559/'
image_urls = [image_url for image_url in get_image_urls(site_url)]
t_list = [image_url for image_url in get_image_urls(t_url)]
image_urls.extend(t_list)
start = time.time()
loop = asyncio.get_event_loop()
tasks = [download_images(url, filename) for filename, url in enumerate(image_urls, start=1)]
coro = asyncio.wait(tasks)
loop.run_until_complete(coro)
loop.close()
print('总计：{:.2f}s'.format(time.time() - start))
if __name__ == '__main__':
test()
4. 以线程方式异步请求
def download_image(image_url, filename):
res = requests.get(image_url)
res.raise_for_status()
image = res.content
with open(r'e:\path\mh\{}.jpg'.format(filename), 'wb') as fp:
fp.write(image)
def test1():
site_url = 'https://www.kuaikanmanhua.com/web/comic/105372/'
t_url = 'https://www.kuaikanmanhua.com/web/comic/15559/'
image_urls = [image_url for image_url in get_image_urls(site_url)]
t_list = [image_url for image_url in get_image_urls(t_url)]
image_urls.extend(t_list)
start = time.time()
loop = asyncio.get_event_loop()
for filename, url in enumerate(image_urls, start=1):
loop.run_in_executor(None, download_image, url, filename)
print('总计：{:.2f}s'.format(time.time() - start))
if __name__ == '__main__':
test1()
这种方式是最快的，244张漫画图片只需要 0.11s。上面的方式大约都要 10s，奇怪的是 3 异步下载需要 9s 多，并没有比正常下载快多少。
5. 异步下载加入进度条，更好的观察下载进度
async def download_images(url, filename):
async with aiohttp.ClientSession() as session:
async with session.get(url) as res:
image = await res.content.read()
with open(r'e:\path\mh\{}.jpg'.format(filename), 'wb') as fp:
fp.write(image)
async def download_images_tqdm(image_urls):
tasks = [download_images(url, filename) for filename, url in enumerate(image_urls, start=1)]
fs = asyncio.as_completed(tasks)
tqdm_iter = tqdm.tqdm(fs, total=len(image_urls))
for future in tqdm_iter:
await future
def test2():
site_url = 'https://www.kuaikanmanhua.com/web/comic/105372/'
t_url = 'https://www.kuaikanmanhua.com/web/comic/15559/'
image_urls = [image_url for image_url in get_image_urls(site_url)]
t_list = [image_url for image_url in get_image_urls(t_url)]
image_urls.extend(t_list)
start = time.time()
loop = asyncio.get_event_loop()
loop.run_until_complete(download_images_tqdm(image_urls))
loop.close()
print('总计：{:.2f}s'.format(time.time() - start))
if __name__ == '__main__':
test2()
6. 使用 concurrent.futures 线程方式请求
def download_image2(*args):
res = requests.get(args[0][1])
res.raise_for_status()
image = res.content
with open(r'e:\path\mh\{}.jpg'.format(args[0][0]), 'wb') as fp:
fp.write(image)
def test3():
site_url = 'https://www.kuaikanmanhua.com/web/comic/105372/'
t_url = 'https://www.kuaikanmanhua.com/web/comic/15559/'
image_urls = [image_url for image_url in get_image_urls(site_url)]
t_list = [image_url for image_url in get_image_urls(t_url)]
image_urls.extend(t_list)
start = time.time()
with futures.ThreadPoolExecutor(max_workers=16) as executor:
executor.map(download_image2, enumerate(image_urls, start=1))
print('总计：{:.2f}s'.format(time.time() - start))
if __name__ == '__main__':
test3()
这种方式根据 max_workers 最大线程数设置不同值，得到的结果差距在 1s 左右，总共耗时 3.95s，比异步请求要快。
总结：
各运行两次
正常下载： 9.44s， 9.87s
异步下载： 9.54s， 3.58s
线程方式异步下载： 0.11s， 0.23s
线程方式下载： 3.87s， 4.32s
最快且相对稳定的是 线程方式异步下载