BrokenPipeErrors while using datastore (dev)

We’ve recently started to see more BrokenPipeErrors while using gcloud-python. We started noticing them more when we upgraded to Kubernetes 1.2.4 (vs 1.1), if that makes any difference. But, I think this was just a coincidence.

Anyway, I delved deeper and saw that the dev datastore version was sending FIN ACK, and then RST ACK packets after some inactivity. The datastore client machine sees these packets as well. The next time the client tries to do a query against datastore, we get a broken pipe error. It would be nice if the gcloud-python / httplib2 did some pre-emptive checking to see if the connection was closed retried the query itself.

Some code snippets:

This is one way to detect if the socket on the other side has closed a connection.

  possibly_disconnected = False
    data_waiting = bytes() 
    try: 
        data_waiting = conn.recv(BUFFER_SIZE, socket.MSG_DONTWAIT|socket.MSG_PEEK) 
    except BlockingIOError: 
        # There is no data available... and the socket still seems good 
        pass 
    else: 
        possibly_disconnected = len(data_waiting) == 0

Here is a stack trace of the exception

  File "/root/pyenvs/my_env/lib/python3.5/site-packages/gcloud/datastore/client.py", line 250, in get
    deferred=deferred)
  File "/root/pyenvs/my_env/lib/python3.5/site-packages/gcloud/datastore/client.py", line 291, in get_multi
    transaction_id=transaction and transaction.id,
  File "/root/pyenvs/my_env/lib/python3.5/site-packages/gcloud/datastore/client.py", line 123, in _extended_lookup
    transaction_id=transaction_id,
  File "/root/pyenvs/my_env/lib/python3.5/site-packages/gcloud/datastore/connection.py", line 203, in lookup
    _datastore_pb2.LookupResponse)
  File "/root/pyenvs/my_env/lib/python3.5/site-packages/gcloud/datastore/connection.py", line 121, in _rpc
    data=request_pb.SerializeToString())
  File "/root/pyenvs/my_env/lib/python3.5/site-packages/gcloud/datastore/connection.py", line 93, in _request
    method='POST', headers=headers, body=data)
  File "/root/pyenvs/my_env/lib/python3.5/site-packages/oauth2client/client.py", line 621, in new_request
    redirections, connection_type)
  File "/root/pyenvs/my_env/lib/python3.5/site-packages/httplib2/__init__.py", line 1314, in request
    (response, content) = self._request(conn, authority, uri, request_uri, method, body, headers, redirections, cachekey)
  File "/root/pyenvs/my_env/lib/python3.5/site-packages/httplib2/__init__.py", line 1064, in _request
    (response, content) = self._conn_request(conn, request_uri, method, body, headers)
  File "/root/pyenvs/my_env/lib/python3.5/site-packages/httplib2/__init__.py", line 988, in _conn_request
    conn.request(method, request_uri, body, headers)
  File "/usr/local/lib/python3.5/http/client.py", line 1083, in request
    self._send_request(method, url, body, headers)
  File "/usr/local/lib/python3.5/http/client.py", line 1128, in _send_request
    self.endheaders(body)
  File "/usr/local/lib/python3.5/http/client.py", line 1079, in endheaders
    self._send_output(message_body)
  File "/usr/local/lib/python3.5/http/client.py", line 911, in _send_output
    self.send(msg)
  File "/usr/local/lib/python3.5/http/client.py", line 885, in send
    self.sock.sendall(data)
BrokenPipeError: [Errno 32] Broken pipe

[jennolsen84]

@dhermes @jonparrott

This SO answer goes over how retries are usually done with requests/urllib3, perhaps it helps:

http://stackoverflow.com/questions/21371809/cleanly-setting-max-retries-on-python-requests-get-or-post-method http://www.coglib.com/~icordasc/blog/2014/12/retries-in-requests.html

I think it would be great to get some of this functionality built in to gcloud-python, and then easily be able to disable the retry mechanism if desired.

This will help users write less retry logic in their app, and can focus on just error handling when service is truly unavailable, etc.

[lukesneeringer]

Hello, One of the challenges of maintaining a large open source project is that sometimes, you can bite off more than you can chew. As the lead maintainer of google-cloud-python, I can definitely say that I have let the issues here pile up.

As part of trying to get things under control (as well as to empower us to provide better customer service in the future), I am declaring a “bankruptcy” of sorts on many of the old issues, especially those likely to have been addressed or made obsolete by more recent updates.

My goal is to close stale issues whose relevance or solution is no longer immediately evident, and which appear to be of lower importance. I believe in good faith that this is one of those issues, but I am scanning quickly and may occasionally be wrong. If this is an issue of high importance, please comment here and we will reconsider. If this is an issue whose solution is trivial, please consider providing a pull request.

Thank you!