Connectex: No connection could be made because the target machine actively refused it

Grafana k6
1

Hello guys.

I have a grpc service written in .net, set up on docker, when trying to connect with more virtual users (over 500) an error occurs:
ERRO[0002] GoError: connection error: desc = ‘transport: error while dialing: dial tcp 127.0.0.1:43333: connectex: No connection could be made because the target machine actively refused it.’
running at reflect.methodValueCall (native).
With the number of users at 100-200 this problem does not occur and the script executes without any problems.

Here’s the script:

import { Client } from "k6/net/grpc";

export const options = {
  scenarios: {
    constantvus: {
      executor: "per-vu-iterations",
      vus: 5000,
      iterations: 1,
    },
  },
};

const client = new Client();
client.load([ ], "../Protos/chat.proto");

export default () => {
  try{
    client.connect("localhost:5080", {
      plaintext: true,
    });
  
    client.close();
  } catch(e) { }
};