英文:
Is it possible for program to crash even with try/except statement that captures Exception in Python?
问题
我正在创建一些自动化程序，用于在特定时间重新启动设备。为了在设备重启后重新连接，我希望在等待一段时间后继续尝试连接，直到最终重新连接成功。由于在重新连接失败时会出现错误，我认为我可以捕获所有异常，然后休眠一段时间，然后再次运行连接代码并继续此循环。然而，我的程序在达到连接错误后仍会崩溃。是否有一些异常无法捕获？
这是我创建的函数供参考，但我仍然遇到各种不同的错误，如“requests.exceptions.ConnectionError”、“urllib3.exceptions.MaxRetryError”、“urllib3.exceptions.NewConnectionError”和“ConnectionRefusedError”。
def establish_session(device):
try:
sess = IdentityServicesEngineAPI(username=config.username,
password=config.password,
base_url='https://' + device,
verify=False)
except Exception as e:
print("连接被拒绝。节点正在重新启动。60秒后重试")
time.sleep(60)
return establish_session(device) # 在此嵌套...
return sess
非常感谢您的反馈。
英文:
I am creating some automation that restarts a device at a certain point. In order to reconnect after it reboots, I want to continue to attempt to connect after a wait period until it finally reconnects. Since there will be errors when it fails to reconnect, I thought I could catch all exceptions and then just sleep for some time period and then run the connection code again and continue this loop. However, my program still crashes after it reaches the connection errors. Are there just some exceptions that can not be caught?
This is the function I created for reference and I am still just getting a bunch of different errors like requests.exceptions.ConnectionError, urllib3.exceptions.MaxRetryError, urllib3.exceptions.NewConnectionError, and ConnectionRefusedError
def establish_session(device):
try:
sess = IdentityServicesEngineAPI(username=config.username,
password=config.password,
base_url='https://' + device,
verify=False)
except Exception as e:
print("connection refused. node rebooting. Trying again in 60 seconds")
time.sleep(60)
return establish_session(device) # Nested here...
return sess
Any feedback would be greatly appreciated
Update: adding full traceback.
Traceback (most recent call last):
File "/python3.10/site-packages/urllib3/connection.py", line 174, in _new_conn
conn = connection.create_connection(
File "/python3.10/site-packages/urllib3/util/connection.py", line 95, in create_connection
raise err
File "/python3.10/site-packages/urllib3/util/connection.py", line 85, in create_connection
sock.connect(sa)
ConnectionRefusedError: [Errno 61] Connection refused
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/python3.10/site-packages/urllib3/connectionpool.py", line 714, in urlopen
httplib_response = self._make_request(
File "/python3.10/site-packages/urllib3/connectionpool.py", line 403, in _make_request
self._validate_conn(conn)
File "/python3.10/site-packages/urllib3/connectionpool.py", line 1053, in _validate_conn
conn.connect()
File "/python3.10/site-packages/urllib3/connection.py", line 363, in connect
self.sock = conn = self._new_conn()
File "/python3.10/site-packages/urllib3/connection.py", line 186, in _new_conn
raise NewConnectionError(
urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPSConnection object at 0x104e2b670>: Failed to establish a new connection: [Errno 61] Connection refused
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/python3.10/site-packages/requests/adapters.py", line 486, in send
resp = conn.urlopen(
File "/python3.10/site-packages/urllib3/connectionpool.py", line 798, in urlopen
retries = retries.increment(
File "/python3.10/site-packages/urllib3/util/retry.py", line 592, in increment
raise MaxRetryError(_pool, url, error or ResponseError(cause))
urllib3.exceptions.MaxRetryError: HTTPSConnectionPool(host='device1', port=443): Max retries exceeded with url: /api/v1/task (Caused by NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x104e2b670>: Failed to establish a new connection: [Errno 61] Connection refused'))
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/python3.10/site-packages/ciscoisesdk/restsession.py", line 497, in request
response = self._req_session.request(method, abs_url, **kwargs)
File "/python3.10/site-packages/requests/sessions.py", line 589, in request
resp = self.send(prep, **send_kwargs)
File "/python3.10/site-packages/requests/sessions.py", line 703, in send
r = adapter.send(request, **kwargs)
File "/python3.10/site-packages/requests/adapters.py", line 519, in send
raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPSConnectionPool(host='device1', port=443): Max retries exceeded with url: /api/v1/task (Caused by NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x104e2b670>: Failed to establish a new connection: [Errno 61] Connection refused'))
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/python3.10/site-packages/urllib3/connection.py", line 174, in _new_conn
conn = connection.create_connection(
File "/python3.10/site-packages/urllib3/util/connection.py", line 95, in create_connection
raise err
File "/python3.10/site-packages/urllib3/util/connection.py", line 85, in create_connection
sock.connect(sa)
ConnectionRefusedError: [Errno 61] Connection refused
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/python3.10/site-packages/urllib3/connectionpool.py", line 714, in urlopen
httplib_response = self._make_request(
File "/python3.10/site-packages/urllib3/connectionpool.py", line 403, in _make_request
self._validate_conn(conn)
File "/python3.10/site-packages/urllib3/connectionpool.py", line 1053, in _validate_conn
conn.connect()
File "/python3.10/site-packages/urllib3/connection.py", line 363, in connect
self.sock = conn = self._new_conn()
File "/python3.10/site-packages/urllib3/connection.py", line 186, in _new_conn
raise NewConnectionError(
urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPSConnection object at 0x104e29930>: Failed to establish a new connection: [Errno 61] Connection refused
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/lib/python3.10/site-packages/requests/adapters.py", line 486, in send
resp = conn.urlopen(
File "/python3.10/site-packages/urllib3/connectionpool.py", line 798, in urlopen
retries = retries.increment(
File "/python3.10/site-packages/urllib3/util/retry.py", line 592, in increment
raise MaxRetryError(_pool, url, error or ResponseError(cause))
urllib3.exceptions.MaxRetryError: HTTPSConnectionPool(host='device1', port=443): Max retries exceeded with url: /api/v1/task (Caused by NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x104e29930>: Failed to establish a new connection: [Errno 61] Connection refused'))
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/lib/python3.10/site-packages/ciscoisesdk/restsession.py", line 504, in request
response = self._req_session.request(method, abs_url,
File "/python3.10/site-packages/requests/sessions.py", line 589, in request
resp = self.send(prep, **send_kwargs)
File "/python3.10/site-packages/requests/sessions.py", line 703, in send
r = adapter.send(request, **kwargs)
File "/python3.10/site-packages/requests/adapters.py", line 519, in send
raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPSConnectionPool(host='device1', port=443): Max retries exceeded with url: /api/v1/task (Caused by NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x104e29930>: Failed to establish a new connection: [Errno 61] Connection refused'))
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/Pre_Post_Checks_Automation/test_api_calls.py", line 5, in <module>
hold = api.tasks.get_task_status().response
File "python3.10/site-packages/ciscoisesdk/api/v3_1_patch_1/tasks.py", line 123, in get_task_status
_api_response = self._session.get(endpoint_full_url, params=_params)
File "/python3.10/site-packages/ciscoisesdk/restsession.py", line 609, in get
response = self.request('GET', url, erc, 0, params=params, **kwargs)
File "python3.10/site-packages/ciscoisesdk/restsession.py", line 507, in request
raise ciscoisesdkException('Socket error {}'.format(e))
ciscoisesdk.exceptions.ciscoisesdkException: Socket error HTTPSConnectionPool(host='device1', port=443): Max retries exceeded with url: /api/v1/task (Caused by NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x104e29930>: Failed to establish a new connection: [Errno 61] Connection refused'))
答案1
得分: 0
回答标题中的问题，是的，有些异常不是Exception。例如，GeneratorExit，KeyboardInterrupt和SystemExit不是Exception的子类，而是BaseException的子类，这意味着它们不会在except Exception子句中被捕获。
请参考此链接以获取内置异常的层次结构：
https://docs.python.org/3/library/exceptions.html#exception-hierarchy
以及来自mCoding的这个非常有用的视频：
https://www.youtube.com/watch?v=zrVfY9SuO64
英文:
To answer the question in the title, yes, some exceptions are not Exception. For example, GeneratorExit, KeyboardInterrupt and SystemExit are not subclasses of Exception but of BaseException, meaning they won't be caught in the except Exception clause.
See this for a hierarchy of builtin exceptions:
https://docs.python.org/3/library/exceptions.html#exception-hierarchy
as well as this very useful video from mCoding:
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
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