gRPC slower as iPerf benchmark

[Kevin Mayrhofer]

Hi, I started using gRPC in a C++ project some time ago. Now I have to send 13 MB of data. And that seemed to be slow for me. So I created a new project with a really simple proto file that only sends a 13 MB array via a synchronous gRPC call. I did the same thing with iPerf. Always over localhost. Now, when I look at Wireshark, it seems like iPerf3 sends the data in about 13ms (from packet 16-246) and gRPC takes about 47ms (from packet 0-179).
I get similar results if i repeat the test. Seemed weird to me, but I'm neither a gRPC nor a Wireshark expert, so maybe I'm missing something.

gRPC: https://drive.google.com/file/d/1aNCUWg4J8yWouwlnBr0joizKUE_ZyPRO/view?usp=sharing

iPerf: https://drive.google.com/file/d/13diJsZE_GeO7b66pbg1ERaE42SglGTAl/view?usp=sharing

Best Regards,
Kevin

[veb...@google.com]

Hi Kevin, performance depends on how you organize your client and backend. https://grpc.io/docs/guides/performance/ would be a good starting point to get better performance.

Also gRPC has a flow control starting from small size of window so it usually takes some time to get the maximum throughput.