KeyError in LanguageServiceClient with 'grpc_asyncio' transport

[nemanja-m]

Hi,

When language_v1.LanguageServiceClient is used with grpc_asyncio transport, a KeyError is raised on any language service method call (e.g. annotate_text).

After investigation, I've found that the issue is in LanguageServiceGrpcAsyncIOTransport.__init__. Stubs are set to empty dictionary after super().__init__ which causes KeyError on service method calls.

Environment details

• OS type and version: macOS Catalina v10.15.6
• Python version: 3.8.5
• pip version: 20.3
• google-cloud-language version: 2.0.0

Steps to reproduce

1. Create a language_v1.LanguageServiceClient client with transport="grpc_asyncio".
2. Call any service method

Code example

from google.cloud import language_v1

client = language_v1.LanguageServiceClient(transport="grpc_asyncio")

document = language_v1.Document(
    content="Example content.",
    language="en",
    type_=language_v1.Document.Type.PLAIN_TEXT,
)

response = client.annotate_text(
    request={
        "document": document,
        "features": {"extract_document_sentiment": True, "classify_text": True},
        "encoding_type": language_v1.EncodingType.UTF8,
    }
)

Stack trace

Traceback (most recent call last):
  File "example.py", line 11, in <module>
    response = client.annotate_text(
  File "/Users/nemanja/.pyenv/versions/example/lib/python3.8/site-packages/google/cloud/language_v1/services/language_service/client.py", line 725, in annotate_text
    rpc = self._transport._wrapped_methods[self._transport.annotate_text]
KeyError: <grpc.aio._channel.UnaryUnaryMultiCallable object at 0x10abc6d90>
Error in sys.excepthook:

Original exception was:

[busunkim96]

Hi,

I'll come take a closer look tomorrow, but my guess is that this is from using the asyncio transport with the regular client. Could you try with the async client instead?

python-language/google/cloud/language_v1/services/language_service/async_client.py

Line 38 in 8c9fdeb

class LanguageServiceAsyncClient:

[nemanja-m]

It seems that we have the same problem because LanguageServiceAsyncClient is using LanguageServiceClient with grpci_asyncio transport.

This means that LanguageServiceGrpcAsyncIOTransport is used as a transport class and _stubs will be set to empty dict after super().__init__ here.

[busunkim96]

Hi,

The plain grpc transport does the same thing with stubs and I haven't seen reports of it causing issues when used with the regular client. The stubs get populated when individual methods are called for the first time.

python-language/google/cloud/language_v1/services/language_service/transports/grpc.py

Lines 233 to 260 in 8c9fdeb

	@property
	def analyze_sentiment(
	self,
	) -> Callable[
	[language_service.AnalyzeSentimentRequest],
	language_service.AnalyzeSentimentResponse,
	]:
	r"""Return a callable for the analyze sentiment method over gRPC.
	Analyzes the sentiment of the provided text.
	Returns:
	Callable[[~.AnalyzeSentimentRequest],
	~.AnalyzeSentimentResponse]:
	A function that, when called, will call the underlying RPC
	on the server.
	"""
	# Generate a "stub function" on-the-fly which will actually make
	# the request.
	# gRPC handles serialization and deserialization, so we just need
	# to pass in the functions for each.
	if "analyze_sentiment" not in self._stubs:
	self._stubs["analyze_sentiment"] = self.grpc_channel.unary_unary(
	"/google.cloud.language.v1.LanguageService/AnalyzeSentiment",
	request_serializer=language_service.AnalyzeSentimentRequest.serialize,
	response_deserializer=language_service.AnalyzeSentimentResponse.deserialize,
	)
	return self._stubs["analyze_sentiment"]

The synchronous client fetches pre-wrapped methods from self._transport._wrapped_methods.

python-language/google/cloud/language_v1/services/language_service/client.py

Lines 316 to 318 in 8c9fdeb

	# Wrap the RPC method; this adds retry and timeout information,
	# and friendly error handling.
	rpc = self._transport._wrapped_methods[self._transport.analyze_sentiment]

python-language/google/cloud/language_v1/services/language_service/transports/base.py

Lines 107 to 122 in 8c9fdeb

	def _prep_wrapped_messages(self, client_info):
	# Precompute the wrapped methods.
	self._wrapped_methods = {
	self.analyze_sentiment: gapic_v1.method.wrap_method(
	self.analyze_sentiment,
	default_retry=retries.Retry(
	initial=0.1,
	maximum=60.0,
	multiplier=1.3,
	predicate=retries.if_exception_type(
	exceptions.ServiceUnavailable, exceptions.DeadlineExceeded,
	),
	),
	default_timeout=600.0,
	client_info=client_info,
	),

This dictionary is only used for (and at the moment only works for) the synchronous client. The async_client wraps the methods with a different method gapic_v1.method_async.wrap_method.

python-language/google/cloud/language_v1/services/language_service/async_client.py

Lines 162 to 176 in 8c9fdeb

	# Wrap the RPC method; this adds retry and timeout information,
	# and friendly error handling.
	rpc = gapic_v1.method_async.wrap_method(
	self._client._transport.analyze_sentiment,
	default_retry=retries.Retry(
	initial=0.1,
	maximum=60.0,
	multiplier=1.3,
	predicate=retries.if_exception_type(
	exceptions.ServiceUnavailable, exceptions.DeadlineExceeded,
	),
	),
	default_timeout=600.0,
	client_info=DEFAULT_CLIENT_INFO,
	)

Even if the async methods were in self._transport._wrapped_methods I don't think you could use the async_client with the synchronous transport or the synchronous client with the async transport. The async client expects an Awaitable.

python-language/google/cloud/language_v1/services/language_service/async_client.py

Lines 259 to 260 in 8c9fdeb

	# Send the request.
	response = await rpc(request, retry=retry, timeout=timeout, metadata=metadata,)

python-language/google/cloud/language_v1/services/language_service/client.py

Lines 320 to 324 in 8c9fdeb

	# Send the request.
	response = rpc(request, retry=retry, timeout=timeout, metadata=metadata,)
	# Done; return the response.
	return response

[nemanja-m]

Hi,

I've tried async client with grpc_asyncio again, and everything works (sorry for the previous wrong results). So the conclusion is that the sync language client should not be configured with grpc_asyncio.

Thank you!

[busunkim96]

@Neenu1995 Yes exactly! The sync client will only work with grpc, and the async client will only work with grpc_asyncio.