Python Requests连接异常：是请求超时还是本地网络故障？

我怀疑自己的某个端点偶尔会出现超时情况，因此编写了一段Python脚本，每隔30秒循环发送POST请求并打印响应内容：

if __name__ == '__main__':
    counter = 0
    while True:
        res = requests.post(url, payload)

        try:
            response = res.json()
        except json.JSONDecodeError:
            response = res.text
        print(response)
        if res.status_code != 201:
            break
        time.sleep(30)
    print(res)
    print(dir(res))
    print(res.status_code)
    print(response)

脚本最终抛出如下异常栈信息：

{'success': True, 'created_on': '2022-09-08 22:42'} # --- 201 response
{'success': True, 'created_on': '2022-09-08 22:43'} # --- 201 response
Traceback (most recent call last):
  File "C:\Users\user\AppData\Local\Programs\Python\Python39\lib\site-packages\urllib3\connection.py", line 169, in _new_conn
    conn = connection.create_connection(
  File "C:\Users\user\AppData\Local\Programs\Python\Python39\lib\site-packages\urllib3\util\connection.py", line 73, in create_connection
    for res in socket.getaddrinfo(host, port, family, socket.SOCK_STREAM):
  File "C:\Users\user\AppData\Local\Programs\Python\Python39\lib\socket.py", line 953, in getaddrinfo
    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno 11004] getaddrinfo failed

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\user\AppData\Local\Programs\Python\Python39\lib\site-packages\urllib3\connectionpool.py", line 699, in urlopen
    httplib_response = self._make_request(
  File "C:\Users\user\AppData\Local\Programs\Python\Python39\lib\site-packages\urllib3\connectionpool.py", line 382, in _make_request
    self._validate_conn(conn)
  File "C:\Users\user\AppData\Local\Programs\Python\Python39\lib\site-packages\urllib3\connectionpool.py", line 1010, in _validate_conn
    conn.connect()
  File "C:\Users\user\AppData\Local\Programs\Python\Python39\lib\site-packages\urllib3\connection.py", line 353, in connect
    conn = self._new_conn()
  File "C:\Users\user\AppData\Local\Programs\Python\Python39\lib\site-packages\urllib3\connection.py", line 181, in _new_conn
    raise NewConnectionError(
urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPSConnection object at 0x000001F5485BB9A0>: Failed to establish a new connection: [Errno 11004] getaddrinfo failed

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\user\AppData\Local\Programs\Python\Python39\lib\site-packages\requests\adapters.py", line 439, in send
    resp = conn.urlopen(
  File "C:\Users\user\AppData\Local\Programs\Python\Python39\lib\site-packages\urllib3\connectionpool.py", line 755, in urlopen
    retries = retries.increment(
  File "C:\Users\user\AppData\Local\Programs\Python\Python39\lib\site-packages\urllib3\util\retry.py", line 574, in increment
    raise MaxRetryError(_pool, url, error or ResponseError(cause))
urllib3.exceptions.MaxRetryError: HTTPSConnectionPool(host='url', port=443): Max retries exceeded with url: /new_lead/5kbLWVNXHQ3U6lJ9trME8hPSf (Caused by NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x000001F5485BB9A0>: Failed to establish a new connection: [Errno 11004] getaddrinfo failed'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\user\dev\pythonProject\main.py", line 13, in <module>
    res = requests.post(
  File "C:\Users\user\AppData\Local\Programs\Python\Python39\lib\site-packages\requests\api.py", line 119, in post
    return request('post', url, data=data, json=json, **kwargs)
  File "C:\Users\user\AppData\Local\Programs\Python\Python39\lib\site-packages\requests\api.py", line 61, in request
    return session.request(method=method, url=url, **kwargs)
  File "C:\Users\user\AppData\Local\Programs\Python\Python39\lib\site-packages\requests\sessions.py", line 542, in request
    resp = self.send(prep, **send_kwargs)
  File "C:\Users\user\AppData\Local\Programs\Python\Python39\lib\site-packages\requests\sessions.py", line 655, in send
    r = adapter.send(request, **kwargs)
  File "C:\Users\user\AppData\Local\Programs\Python\Python39\lib\site-packages\requests\adapters.py", line 516, in send
    raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPSConnectionPool(host='url', port=443): Max retries exceeded with url: /new_lead/5kbLWVNXHQ3U6lJ9trME8hPSf (Caused by NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x000001F5485BB9A0>: Failed to establish a new connection: [Errno 11004] getaddrinfo failed'))

我的疑问：如果是服务器超时，应该会返回500状态码，脚本也会退出循环并打印响应对象。那这个异常是否意味着我的本地网络断开，导致脚本无法发起请求？

解答 #

这个异常核心是DNS解析失败，不是服务器超时，也不一定是本地网络完全断开，具体说明：

1. 错误本质
   socket.gaierror: [Errno 11004] getaddrinfo failed 表示Python调用getaddrinfo函数时无法将目标域名解析为对应的IP地址。这个步骤发生在建立HTTP连接之前，连请求都没发出去，自然不会有服务器返回的响应对象，直接触发连接异常。

2. 和服务器超时的区别

   • 服务器超时（比如请求发送后长时间没响应）会触发requests.exceptions.Timeout异常；如果服务器返回5xx状态码，你能正常拿到res对象，脚本会进入状态码判断逻辑。
   • 而当前错误是连接建立前的失败，根本没和服务器建立通信。

3. 可能的原因

   • 本地DNS服务器无法解析目标域名（比如DNS服务临时故障）
   • 本地网络的DNS配置错误
   • 目标域名的DNS记录临时变更或失效
   • 本地网络波动（比如WiFi断连瞬间、网络丢包导致DNS请求失败）

4. 脚本优化建议
   给请求增加异常捕获和超时设置，避免脚本直接崩溃，同时记录异常信息：

if __name__ == '__main__':
    import requests
    import json
    import time

    url = "你的目标URL"
    payload = {}

    while True:
        try:
            # 设置超时时间，避免无限等待
            res = requests.post(url, payload, timeout=10)
            try:
                response = res.json()
            except json.JSONDecodeError:
                response = res.text
            print(response)
            if res.status_code != 201:
                print(f"收到非201状态码: {res.status_code}")
                break
        except requests.exceptions.ConnectionError as e:
            print(f"连接错误: {str(e)}")
            # 可以选择继续循环或做其他处理
        except requests.exceptions.Timeout as e:
            print(f"请求超时: {str(e)}")
        time.sleep(30)

内容的提问来源于stack exchange，提问作者codego