Internal gRPC error when querying for data

[Tomás Sabat Stöfsel]

(this bug only happens sometimes)

Description

I am testing client python with different read queries. Before running into the errors described below, the query was working fine. But after running it twice, I now get the Exceptions below.

Environment

1. OS: Mac OS 10.14
2. Grakn version: Grakn Core 2.0.0-alpha
3. Grakn client-python version: client-python 2.0.0-alpha-4
4. Python version: 3.9

Reproducible Steps

Steps to create the smallest reproducible scenario:

1. Run this grakn distribution: https://www.dropbox.com/s/1y3ophwlv6xyg2z/grakn-2.0-alpha-tomas-20210109.zip?dl=0
2. In a terminal run python, and run:

from grakn.client import GraknClient, SessionType, TransactionType
client = GraknClient("localhost:1729")
session = client.session("biograkn_covid_16", SessionType.DATA)
tx = session.transaction(TransactionType.READ)
answer_iterator = tx.query().match("match $x isa protein, has uniprot-id $uid; get $uid;")
for answer in answer_iterator:
	person = answer.get("uid")
	print("Retrieved protein with id " + person.get_iid())

4. After some data gets returned, I see this error:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/grakn/rpc/stream.py", line 57, in __next__
    return next(self)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/grakn/rpc/stream.py", line 50, in __next__
    res = self._transaction._fetch(self._request_id)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/grakn/rpc/transaction.py", line 136, in _fetch
    response = next(self._response_iterator)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/grpc/_channel.py", line 416, in __next__
    return self._next()
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/grpc/_channel.py", line 778, in _next
    operating = self._call.operate(
  File "src/python/grpcio/grpc/_cython/_cygrpc/channel.pyx.pxi", line 277, in grpc._cython.cygrpc.IntegratedCall.operate
  File "src/python/grpcio/grpc/_cython/_cygrpc/channel.pyx.pxi", line 102, in grpc._cython.cygrpc._operate_from_integrated_call
  File "src/python/grpcio/grpc/_cython/_cygrpc/channel.pyx.pxi", line 110, in grpc._cython.cygrpc._operate_from_integrated_call
  File "src/python/grpcio/grpc/_cython/_cygrpc/channel.pyx.pxi", line 57, in grpc._cython.cygrpc._raise_call_error_no_metadata
ValueError: Internal gRPC call error 8. Please report to https://github.com/grpc/grpc/issues

5. Then I run again:

answer_iterator = tx.query().match("match $x isa protein, has uniprot-id $uid; get $uid;")
for answer in answer_iterator:
	person = answer.get("uid")
	print("Retrieved protein with id " + person.get_iid())

And I see this error:

Exception in thread Thread-29:
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/threading.py", line 954, in _bootstrap_inner
    self.run()
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/threading.py", line 892, in run
    self._target(*self._args, **self._kwargs)
  File "src/python/grpcio/grpc/_cython/_cygrpc/thread.pyx.pxi", line 53, in grpc._cython.cygrpc._run_with_context._run
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/grpc/_channel.py", line 1238, in channel_spin
    call_completed = event.tag(event)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/grpc/_channel.py", line 166, in handle_event
    callbacks = _handle_event(event, state, response_deserializer)
  File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/grpc/_channel.py", line 131, in _handle_event
    state.due.remove(operation_type)
KeyError: 5

Expected Output

I expect data to be returned in the console.

Actual Output

The first error returns a ValueError: Internal gRPC call error 8., and the second time I am returned with an Exception in thread Thread-29:

Additional information

After this error, I close both the session and transaction. After I open a new session, I try to open a new transaction. However, this hangs and nothing happens:

[Tomás Sabat Stöfsel]

With the latest version (Alpha-2.0.0-version2) I am unable to reproduce this bug.

[Haikal Ryclova-Pribadi]

We've proceeded far beyond the steps above with BioGrakn now. So we can safely assume this bug no longer exists. Going to close it for now.