performance limitation of one client process #21332

[reme...@gmail.com]

What version of gRPC and what language are you using?

1.20

What operating system (Linux, Windows,...) and version?

linux

What runtime / compiler are you using (e.g. python version or version of gcc)

gcc

What did you do?

rpc communication from c++ grpc client to java grpc server.

one process, multiple threads(10-50), and one new channel/client (grpc::CreateChannel) per thread. When I start one process and send message from each threads through its rpc client, I can get only 6500qps/334MB/s. When I start two processes and send message with same pattern , I can get 11700qps/620MB/s.
After looking into the state, I found there is only one socket connected to the server for each process, even there is multiple client/channel sending messages to the server.
I'm guessing whether the online socket number is the root cause of bandwidth limitation.
Any response is appreciated.

What did you expect to see?

multiple http2 socket connections.

What did you see instead?

only one http2 socket connection.

[Sivaram Kumar Battu]

Subchannel pooling is enabled in gRPC around 1.8.0 version

If you start multiple connections to the same target from different threads within the same program they start using the same endpoint on the client side.

Starting from 1.19 version, there is an option to override this behavior by setting the following knob.

https://github.com/grpc/grpc/blob/2c6a7e1f19a899e88d2050a1cb5d05079598e880/include/grpc/impl/codegen/grpc_types.h#L396

If you specify this argument during channel creation time, you should be able to get one socket per each channel, sample below from C++ tests.

https://github.com/grpc/grpc/blob/526fcb5c7d4e48192edd8fdbba408101d23848f2/test/core/tsi/alts/handshaker/alts_concurrent_connectivity_test.cc#L87

Best,

- Ram.

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