h2
h2 copied to clipboard
StreamIDTooLowError when trying to send headers into closed stream
Hi!
I'm getting errors like this on the server-side:
Traceback (most recent call last):
File "/usr/local/lib/python3.6/dist-packages/grpclib/server.py", line 310, in request_handler
await method.func(stream)
File "/usr/local/lib/python3.6/dist-packages/featureflags/server/rpc/service.py", line 51, in Exchange
await self._queue.StoreStats.add(task, timeout=timeout)
File "/usr/local/lib/python3.6/dist-packages/taskqueue/client/queue.py", line 21, in add
await self._task_queue_stub.Add(task, timeout=timeout)
File "/usr/local/lib/python3.6/dist-packages/grpclib/client.py", line 473, in __call__
return await stream.recv_message()
File "/usr/local/lib/python3.6/dist-packages/grpclib/client.py", line 286, in recv_message
await self.recv_initial_metadata()
File "/usr/local/lib/python3.6/dist-packages/grpclib/client.py", line 221, in recv_initial_metadata
headers = await self._stream.recv_headers()
File "/usr/local/lib/python3.6/dist-packages/grpclib/protocol.py", line 215, in recv_headers
return await self.__headers__.get()
File "/usr/lib/python3.6/asyncio/queues.py", line 167, in get
yield from getter
concurrent.futures._base.CancelledError
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/usr/local/lib/python3.6/dist-packages/h2/connection.py", line 585, in _get_or_create_stream
return self.streams[stream_id]
KeyError: 48141
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/usr/local/lib/python3.6/dist-packages/grpclib/server.py", line 325, in request_handler
raise
File "/usr/local/lib/python3.6/dist-packages/grpclib/server.py", line 220, in __aexit__
status_message=status_message)
File "/usr/local/lib/python3.6/dist-packages/grpclib/server.py", line 170, in send_trailing_metadata
await self._stream.send_headers(headers, end_stream=True)
File "/usr/local/lib/python3.6/dist-packages/grpclib/protocol.py", line 267, in send_headers
end_stream=end_stream)
File "/usr/local/lib/python3.6/dist-packages/h2/connection.py", line 763, in send_headers
stream_id, AllowedStreamIDs(self.config.client_side)
File "/usr/local/lib/python3.6/dist-packages/h2/connection.py", line 587, in _get_or_create_stream
return self._begin_new_stream(stream_id, allowed_ids)
File "/usr/local/lib/python3.6/dist-packages/h2/connection.py", line 454, in _begin_new_stream
raise StreamIDTooLowError(stream_id, highest_stream_id)
h2.exceptions.StreamIDTooLowError: StreamIDTooLowError: 48141 is lower than 48143
This happens when client cancels stream with RST_STREAM, and on the server-side I have a logic which looks like this:
try:
conn.send_headers(stream_id, [...])
except h2.exceptions.StreamClosedError:
pass
And sometimes I'm getting StreamIDTooLowError
exception instead of StreamClosedError
, because this behavior depends on H2Connection.streams
dictionary, where streams are removed nondeterministically.
I think that H2Connection._get_or_create_stream
function should check not only H2Connection.streams
but also H2Connection._closed_streams
.
Of course I can refactor my code and check that stream is closed by myself, but I still think that there is a bug in H2Connection.send_headers
method.
Or it wasn't right to rely on StreamClosedError in the first place?