Protobuf Unexpected end-group tag

[Wei Chiang Lim]

Hi all

I'm trying parse protobuf messages subscribed from a zeromq feed using Python. Intermittently when I parse the message string, my script crashes with the following error

  File "ale-feed-location-reader.py", line 37, in <module>

    aleEvent.ParseFromString(recvMsg)

  File "/usr/lib/python2.7/dist-packages/google/protobuf/message.py", line 182, in ParseFromString

    self.MergeFromString(serialized)

  File "/usr/lib/python2.7/dist-packages/google/protobuf/internal/python_message.py", line 798, in MergeFromString

    raise message_mod.DecodeError('Unexpected end-group tag.')

google.protobuf.message.DecodeError: Unexpected end-group tag.

My script looks like the following, seems fairly simple enough. Has anyone seen this before, and how would you fix this? My guess is that it is not any corruption on the message from the zmq server, as a vendor provided c++ compiled program is able to parse the messages without any problem.

----------snip----------

# Socket to talk to server

context = zmq.Context()

clientSock = context.socket(zmq.SUB)

clientSock.connect ("tcp://%s:%s" % (serverAddr, serverPort))

print('Connected to {0} at port {1}'.format(serverAddr, serverPort))

topicfilter = ""

clientSock.setsockopt(zmq.SUBSCRIBE, topicfilter)

while(1):

# Receive Message

recvMsg = ''.join(clientSock.recv_multipart())

# Parse Message

aleEvent = schema_pb2.nb_event()

aleEvent.ParseFromString(recvMsg)

if aleEvent.IsInitialized():

time = datetime.datetime.fromtimestamp(aleEvent.timestamp)

----------snip----------

Thanks for any insight!

[Jie Luo]

We are going to change the c++ implementation to the same behavior
with pure python which will raise 'Unexpected end-group tag.' too.
Please see http://b/27494216

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[Lim Wei Chiang]

Hi Jie Luo,

What does the error denote, what should I be checking for?

The link you sent has a typo I believe.

Thanks for any advice.

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[Jie Luo]

It checks the end group tag 4 which should be deprecated.

https://developers.google.com/protocol-buffers/docs/encoding#structure

[vladimir...@teamaol.com]

Hi Jie Luo,

Could you explain a little more which C++ code you are talking about - one that creates message
(that is later parsed in Python) or something else?

If so, could you provide your changes?

Thanks,
Vladimir

Thanks for any advice.

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[Jie Luo]

I am talking about C++ implementation for python. We should add more checks for MergeFromString() in message.cc. I have a change in internal code, however it was blocked by another team because they have a lot of  corrupted data which haven't fix yet

Thanks for any advice.

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