Suggestion with cluster module when use "maxConnection" in its worker process

[EchoFUN]

What is the problem this feature will solve?

When the node service is under a very high load, multiple connections are processed at the same time in one worker ( we use the cluster module currently in our project ). We set the "maxConnections" to limit the connections of the worker. But we found that if a new request reach the limit of the "maxConnections", the request will retry on other workers. I think can we have an option, if a new request reach the limit, we can just drop the request instead of retrying the request on other workers ? Because as the system is under a very high load, the other workers may also be very busy at this moment. Here is a example on "v22.7.0".

const cluster = require('cluster');
const http = require('http');
const process = require('process');

if (cluster.isPrimary) {
  console.log(`Master ${process.pid} is running.\n`);
  for (let i = 0; i < 1; i++) {
    cluster.fork();
  }
} else {
  const server = http.createServer((req, res) => {
    res.writeHead(200);
    res.end('hello world\n');
  });

  server.maxConnections = 0;

  server.listen(8000, () => {
    console.log(`Worker ${process.pid} started`);
  });
}

What is the feature you are proposing to solve the problem?

For example, add An option "--maxconnections-drop-request" to the node "Command-line options" while on start up.

What alternatives have you considered?

No response

[EchoFUN]

The above sample code is used to better demonstrating this issue, it will cause the request to fail to return, and the CPU will run to the usage of 50%+.

[theanarkh]

I think it makes sense.

[EchoFUN]

And on the documentation, it says "It is not recommended to use this option once a socket has been sent to a child with child_process.fork()." So, I can think of it as not recommended to use this API in cluster mode ? Is anyone have more detail information about it ? Thanks. It may be useful while the traffic is much heavy.

[theanarkh]

I think It is not recommended to use this option in chld_process module.

If process A receives a socket, then process A's maxConnection will increase by one, and then you send it to process B, and process B's maxConnection will also increase by one, which may not be your expected behavior.

But I think it is ok if you close the socket of process A after sending successfully because the maxConnection will reduced by one.