requests.Session, retry on network errors

session.py

import requests
from requests.adapters import HTTPAdapter
from urllib3.util.retry import Retry


def create_session(num_hosts: int, num_workers: int, retry: int) -> requests.Session:
  session = requests.Session()
  adapter = HTTPAdapter(
      pool_connections=num_hosts,   # number of different hosts we will be talking to
      pool_maxsize=num_workers,     # number of maximum concurrent requests the session will be doing (i.e. with multiple threads that share it)
      max_retries=Retry(
        total=retry,
        read=retry,
        connect=retry,
        status=retry,
        backoff_factor=0.3,
        status_forcelist=Retry.RETRY_AFTER_STATUS_CODES.union((500, 502, 503, 504)),
    ),
  )
  session.mount("http://", adapter)
  session.mount("https://", adapter)
  return session