Protobuf messages are thread-compatible. You can read a protobuf message
concurrently in multiple threads. But if you need to update it at the same
time, all threads must acquire a lock before accessing or updating the
message.
On Tuesday, January 15, 2013 7:45:35 PM UTC+8, Johannes Wienke wrote:
>
> Hi,
>
> I couldn't find any information about whether the python generated classes
> are thread-safe, or can at least be used for read-only purposes by several
> threads in parallel. Is anything known about that?
>
> The reason I am asking is that we receive an exception in one of our
> systems where actually two threads are operating on a message in parallel.
> One prints out the whole message and the other one reads some attributes
> from the message. The printing thread consistently crashes with the
> following backtrace:
>
> File
> "/vol/humavips/releases/y3demo/lib/python2.7/site-packages/rsb_python-0.7.0-py2.7.egg/rsb/util.py",
> line 252, in push
> self.__logger.debug("Got new message to dispatch: %s" % message)
> File
> "/vol/humavips/releases/y3demo/lib/python2.7/site-packages/rsb_python-0.7.0-py2.7.egg/rsb/__init__.py",
> line 1068, in __str__
> % ("Event", self.__id, self.__scope, printData, self.__type,
> self.__metaData, self.__causes)
> File
> "/usr/lib/python2.7/dist-packages/google/protobuf/internal/python_message.py",
> line 660, in __str__
> return text_format.MessageToString(self)
> File "/usr/lib/python2.7/dist-packages/google/protobuf/text_format.py",
> line 58, in MessageToString
> PrintMessage(message, out, as_utf8=as_utf8, as_one_line=as_one_line)
> File "/usr/lib/python2.7/dist-packages/google/protobuf/text_format.py",
> line 67, in PrintMessage
> for field, value in message.ListFields():
> File
> "/usr/lib/python2.7/dist-packages/google/protobuf/internal/python_message.py",
> line 554, in ListFields
> all_fields = [item for item in self._fields.iteritems() if
> _IsPresent(item)]
> RuntimeError: dictionary changed size during iteration
>
>
> Would be nice if someone could point out the exact threading guarantees of
> the python API.
>
> Kind regards,
> Johannes
>
--
You received this message because you are subscribed to the Google Groups
"Protocol Buffers" group.
To view this discussion on the web visit
https://groups.google.com/d/msg/protobuf/-/KVRYLPZ0knsJ.
To post to this group, send email to protobuf@googlegroups.com.
To unsubscribe from this group, send email to
protobuf+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/protobuf?hl=en.
