Port seems to be shared between to separate grpc channels in same process

user_1543167 0
Viewed 217

My questions concerns gRPC clients using the C core, specifically C++

I've been debugging one of our servers, and I've noticed a certain two-client flow worked when the clients were launched from separate processes (two separate console windows) but not from within an automated test case (which runs within a single process). The flow in question involves two "clients" (channels, basically) which are alive at the same time and concurrently issuing requests to the same server

Digging further, I discovered that in the working flow the server received requests from two different ip:port combinations: 127.0.0.1:xxxx and 127.0.0.1:yyyy. In the failing scenario however, both requests come from the same ip:port.

I create a separate channel for every client, so this behavior confused me. I have a couple of questions

  1. Does gRPC share ports between channels in the same process like this? If not, then I have to imagine there's a bug in my code
  2. If yes to (1), is there any way to avoid this port reuse?

I do see the "grpc.so_reuseport" option in the channel's metadata, and note that it is enabled by default. This seems more related to servers than clients (though perhaps I'm making an arbitrary distinction), but I'll disable it and try things out

EDIT: The so_reuseport option doesn't do anything, but I am on Windows so I should have expected that anyways :/ I also found a related question without any answers here

EDIT 2: The discussion on this question seems promising. Will try it out and report back

grpc
1 Answers

This is mentioned/explained in the question I link in edit 2, but the answer is to use

auto metadata = grpc::ChannelArguments();
metadata.SetInt(GRPC_ARG_USE_LOCAL_SUBCHANNEL_POOL, 1);

and pass it to grpc::CreateCustomChannel

user_15431670
Related