tonic client server side streaming call blocks when interfacing with csharp grpc server

[dougcooper]

I've tested this against a rust service and csharp service that effectively blocks forever before writing to the stream and am seeing different client behavior as follows:

• In the case of the rust service my tonic client gets a valid stream and i can call .next() to wait for a message.
• In the case of the csharp service my tonic client never returns from the initial api call and so i never have a valid stream to iterate over

In both cases i sleep in order to simulate a stream that doesnt have any data immediately available.

What Im trying to do is make several streaming based api calls and then use tokio::select! to multiplex the responses in an infinite loop or until a stream gets dropped.

Please let me know if i can clarify...cheers

[LucioFranco]

What sleep are you using in rust?

[dougcooper]

tokio::time::sleep(Duration::from_secs(3600)).await;

[LucioFranco]

Its hard to say without the full code context unfortunately.

[dougcooper]

I recreated the issue using trivially modified off the shelf examples and a python service. here's the setup:

python server (rust client does not return a stream when no data immediately available)

git clone https://github.com/dougcooper/grpc-test && cd grpc-test/examples/python
python3 -m venv .venv
. .venv/bin/activate
pip3 install grpcio-tools grpcio
make
python3 hellostreamingworld/async_greeter_server.py

rust server (rust client gets a stream as expected with no data immediately available)

git clone https://github.com/dougcooper/tonic-test && cd tonic-test/examples
cargo run --bin streaming-server

rust client

cargo run --bin streaming-client

expected behavior

after running the server then launching the client i should see a client log message that says "we have a stream" but not receive any data due to server side sleep.

[dougcooper]

i also tested the async_greeter_client.py against the async_greeter_server.py and it works as expected.

[LucioFranco]

If you think its a proper bug then I would open an issue with a minimal reproduction.