python使用gevent实现协程，限制gevent协程数量

from gevent import monkey
from gevent.pool import Pool

# 猴子补丁，替换底层thread/socket实现非阻塞
monkey.patch_all()
import gevent
import requests


def func(url):
    print('GET: %s' % url)
    resp = requests.get(url)
    data = resp.text
    print('%d bytes received from %s.' % (len(data), url))
    result_list.append(data)


result_list = []
if __name__ == "__main__":
    # gevent实现协程
    gevent.joinall([
        gevent.spawn(func, 'https://www.python.org/'),
        gevent.spawn(func, 'https://www.yahoo.com/'),
        gevent.spawn(func, 'https://github.com/'),
    ])
    print(f'result length:{len(result_list)}')

    # gevent限制协程数量
    inputs = ['https://www.python.org/', 'https://www.yahoo.com/', 'https://github.com/', 'https://www.baidu.com',
              'https://www.qq.com', 'https://www.meituan.com', 'https://www.iqiyi.com']
    pool = Pool(5)
    threads = [pool.spawn(func, i) for i in inputs]
    gevent.joinall(threads)
    print(f'finish1, data length:{len(result_list)}')

结果:

"D:\Program Files\Python36\python.exe" "D:\Program Files\JetBrains\PyCharm Community Edition 2019.2.4\helpers\pydev\pydevd.py" --multiproc --qt-support=auto --client 127.0.0.1 --port 62826 --file D:/04_project/tools/tools/yield_request.py
pydev debugger: process 3876 is connecting

Connected to pydev debugger (build 192.7142.42)
GET: https://www.python.org/
GET: https://www.yahoo.com/
GET: https://github.com/
50225 bytes received from https://www.python.org/.
219487 bytes received from https://github.com/.
632593 bytes received from https://www.yahoo.com/.
result length:3


GET: https://www.python.org/
GET: https://www.yahoo.com/
GET: https://github.com/
GET: https://www.baidu.com
GET: https://www.qq.com     # 执行5个协程后等待返回结果 
2443 bytes received from https://www.baidu.com.
GET: https://www.meituan.com
99681 bytes received from https://www.qq.com.
GET: https://www.iqiyi.com
50225 bytes received from https://www.python.org/.
38273 bytes received from https://www.meituan.com.
219493 bytes received from https://github.com/.
325656 bytes received from https://www.iqiyi.com.
628076 bytes received from https://www.yahoo.com/.
finish1, data length:10

Process finished with exit code 0