Aiohttp: How to handle ClientResponseError/ServerDisconnectedError properly
Hi,
It's not a bug, but a question. I am using this library to load a lot of http-files over a proxy. After some successful requests I always get a ServerDisconnectedError.
Is there a way to enable some sort of "auto-reconnect" and what is the recommended technique to handle this error?
Task exception was never retrieved
future: <Task finished coro=<load() done, defined at run.py:21> exception=ServerDisconnectedError()>
Traceback (most recent call last):
File "/usr/lib/python3.5/asyncio/tasks.py", line 237, in _step
result = coro.throw(exc)
File "run.py", line 23, in load
page = await fetch_page(client, 'http://example.com/{}'.format(channel))
File "run.py", line 12, in fetch_page
async with session.get(url, headers={' User-Agent': 'myuseragent'}) as response:
File "/var/loadViews/env/lib/python3.5/site-packages/aiohttp/client.py", line 538, in __aenter__
self._resp = yield from self._coro
File "/var/loadViews/env/lib/python3.5/site-packages/aiohttp/client.py", line 183, in _request
conn = yield from self._connector.connect(req)
File "/var/loadViews/env/lib/python3.5/site-packages/aiohttp/connector.py", line 310, in connect
transport, proto = yield from self._create_connection(req)
File "/var/loadViews/env/lib/python3.5/site-packages/aiohttp/connector.py", line 689, in _create_connection
resp = yield from proxy_resp.start(conn, True)
File "/var/loadViews/env/lib/python3.5/site-packages/aiohttp/client_reqrep.py", line 606, in start
message = yield from httpstream.read()
File "/var/loadViews/env/lib/python3.5/site-packages/aiohttp/streams.py", line 591, in read
result = yield from super().read()
File "/var/loadViews/env/lib/python3.5/site-packages/aiohttp/streams.py", line 446, in read
yield from self._waiter
File "/usr/lib/python3.5/asyncio/futures.py", line 385, in __iter__
yield self # This tells Task to wait for completion.
File "/usr/lib/python3.5/asyncio/tasks.py", line 288, in _wakeup
value = future.result()
File "/usr/lib/python3.5/asyncio/futures.py", line 274, in result
raise self._exception
aiohttp.errors.ServerDisconnectedError
outdated
inkrement
All 6 comments
I had similar problem and I was hoping that aiohttp could have a retry logic on connection errors and possible on HTTP status. Because there isn't just thing yet available I came up with the following which works for REST APIs where json is returned::
HTTP_STATUS_CODES_TO_RETRY = [500, 502, 503, 504]
class FailedRequest(Exception):
"""
A wrapper of all possible exception during a HTTP request
"""
code = 0
message = ''
url = ''
raised = ''
def __init__(self, *, raised='', message='', code='', url=''):
self.raised = raised
self.message = message
self.code = code
self.url = url
super().__init__("code:{c} url={u} message={m} raised={r}".format(
c=self.code, u=self.url, m=self.message, r=self.raised))
async def send_http(session, method, url, *,
retries=1,
interval=0.9,
backoff=3,
read_timeout=15.9,
http_status_codes_to_retry=HTTP_STATUS_CODES_TO_RETRY,
**kwargs):
"""
Sends a HTTP request and implements a retry logic.
Arguments:
session (obj): A client aiohttp session object
method (str): Method to use
url (str): URL for the request
retries (int): Number of times to retry in case of failure
interval (float): Time to wait before retries
backoff (int): Multiply interval by this factor after each failure
read_timeout (float): Time to wait for a response
"""
backoff_interval = interval
raised_exc = None
attempt = 0
if method not in ['get', 'patch', 'post']:
raise ValueError
if retries == -1: # -1 means retry indefinitely
attempt = -1
elif retries == 0: # Zero means don't retry
attempt = 1
else: # any other value means retry N times
attempt = retries + 1
while attempt != 0:
if raised_exc:
log.error('caught "%s" url:%s method:%s, remaining tries %s, '
'sleeping %.2fsecs', raised_exc, method.upper(), url,
attempt, backoff_interval)
await asyncio.sleep(backoff_interval)
# bump interval for the next possible attempt
backoff_interval = backoff_interval * backoff
log.info('sending %s %s with %s', method.upper(), url, kwargs)
try:
with aiohttp.Timeout(timeout=read_timeout):
async with getattr(session, method)(url, **kwargs) as response:
if response.status == 200:
try:
data = await response.json()
except json.decoder.JSONDecodeError as exc:
log.error(
'failed to decode response code:%s url:%s '
'method:%s error:%s response:%s',
response.status, url, method.upper(), exc,
response.reason
)
raise aiohttp.errors.HttpProcessingError(
code=response.status, message=exc.msg)
else:
log.info('code:%s url:%s method:%s response:%s',
response.status, url, method.upper(),
response.reason)
raised_exc = None
return data
elif response.status in http_status_codes_to_retry:
log.error(
'received invalid response code:%s url:%s error:%s'
' response:%s', response.status, url, '',
response.reason
)
raise aiohttp.errors.HttpProcessingError(
code=response.status, message=response.reason)
else:
try:
data = await response.json()
except json.decoder.JSONDecodeError as exc:
log.error(
'failed to decode response code:%s url:%s '
'error:%s response:%s', response.status, url,
exc, response.reason
)
raise FailedRequest(
code=response.status, message=exc,
raised=exc.__class__.__name__, url=url)
else:
log.warning('received %s for %s', data, url)
print(data['errors'][0]['detail'])
raised_exc = None
except (aiohttp.errors.ClientResponseError,
aiohttp.errors.ClientRequestError,
aiohttp.errors.ClientOSError,
aiohttp.errors.ClientDisconnectedError,
aiohttp.errors.ClientTimeoutError,
asyncio.TimeoutError,
aiohttp.errors.HttpProcessingError) as exc:
try:
code = exc.code
except AttributeError:
code = ''
raised_exc = FailedRequest(code=code, message=exc, url=url,
raised=exc.__class__.__name__)
else:
raised_exc = None
break
attempt -= 1
if raised_exc:
raise raised_exc
unixsurfer
on 16 Apr 2016
👍11
👎3
wow. great, Thanks!
inkrement
on 16 Apr 2016
Don't forget to adjust the parsing of the json as it is very specific to my needs.
unixsurfer
on 17 Apr 2016
My question is whether this error is related only to this library, and should thus always be ignored/caught/retried, or whether I should expect that this error could also be due to something server-sided?
kootenpv
on 4 May 2018
The exception is raised when a peer had closed the socket.
It's up to you how to process this situation.
asvetlov
on 4 May 2018
👍2
Try setting the client to tell the server to close the connection after each request:
self._session = aiohttp.ClientSession(
...
headers={"Connection": "close"},
)
HTTP keep-alive allows the same connection to be used for multiple requests, which can improve performance, especially over HTTPS, where the connection handshake can be lengthy. But the server may have a limit as to how long it's willing to keep the connection alive or how many requests it will accept on the same connection. When the limit runs out, it closes the connection.
rogerdahl
on 11 Mar 2019
👍7
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Most helpful comment
I had similar problem and I was hoping that aiohttp could have a retry logic on connection errors and possible on HTTP status. Because there isn't just thing yet available I came up with the following which works for REST APIs where json is returned::