'Connection' object has no attribute '_transport'

[n00bsys0p]

Hi,

I am and have been regularly seeing this in our server logs. It's constant and quite frequent. I've had a look through the library and I can't see anywhere that would allow a Connection to have no Transport, as it's assigned in the constructor.

Here's a traceback (apologies for formatting, it's copied directly from our remote logging provider):

Task exception was never retrieved
future: <Task finished coro=<request_handler() done, defined at /usr/local/lib/python3.7/dist-packages/grpclib/server.py:342> exception=AttributeError("'Connection' object has no attribute '_transport'")>

grpclib/protocol.py in flush at line 219
                      stream_id=stream_id, wrapper=wrapper)

    def flush(self) -> None:
        data = self._connection.data_to_send()
        if data:
            self._transport.write(data)

    def close(self) -> None:
        if hasattr(self, '_transport'):
            self._transport.close()
            # remove cyclic references to improve memory usage

grpclib/protocol.py in ack at line 199
        return self._connection.receive_data(data)  # type: ignore

    def ack(self, stream_id: int, size: int) -> None:
        if size:
            self._connection.acknowledge_received_data(size, stream_id)
            self.flush()

    def pause_writing(self) -> None:
        self.write_ready.clear()

    def resume_writing(self) -> None:

        def release_stream(*, _streams: _Streams = self.streams) -> None:
            assert stream.id is not None
            _stream = _streams.pop(stream.id)
            self.connection.stream_close_waiter.set()
            self.connection.ack(stream.id, _stream.buffer.unacked_size())
        return release_stream

    def close(self, reason: str = 'Connection closed') -> None:
        self.connection.close()

grpclib/server.py in request_handler at line 446
    except ProtocolError:
        log.exception('Application error')
    except Exception:
        log.exception('Server error')
    finally:
        release_stream()

class _GC(abc.ABC):
    _gc_counter = 0

[nickpro]

met the same error

[vmagamedov]

This is not critical but should be fixed. We have an optimisation to remove cyclic references, that's why this error is so cryptic.

grpclib/grpclib/protocol.py

Line 243 in 0c20bb5

del self._transport

release_stream is trying to send information over a connection, but connection is already closed. We have to add a check for this case.

[edigaryev]

@vmagamedov care to cut a new PyPI release?

[vmagamedov]

@edigaryev just released https://pypi.org/project/grpclib/0.3.2rc2/, proper version release will follow very soon