Support grpc.so_reuseport in @grpc/grpc-js on Linux #3108

Is your feature request related to a problem? Please describe.

We want to run multiple worker threads for one gRPC service, all listening on the same port.

grpc-js currently ignores:

  new grpc.Server({
    'grpc.so_reuseport': 1
  });

so the second worker fails with EADDRINUSE.

This came up before in #794 and #1547. In #1547, Node did not yet expose a JavaScript API for SO_REUSEPORT. It does now:

  http2Server.listen({ host, port, reusePort: true });

Describe the solution you'd like

Make grpc-js honor grpc.so_reuseport when binding a TCP listener.

Something along these lines:

  const listenAddress =
    this.options['grpc.so_reuseport'] === 1 && 'port' in address
      ? { ...address, reusePort: true }
      : address;

  http2Server.listen(listenAddress, callback);

No behavior change unless the option is explicitly set to 1.

Describe alternatives you've considered

We can maintain a local patch-package patch or monkey-patch grpc-js internals, but both depend on private implementation details and need maintenance on grpc-js upgrades.

Keeping one worker per gRPC process works, but prevents worker-thread scaling.

Additional context

This is for several workers of the same service sharing one endpoint, not unrelated services sharing a port.

Linux only is fine for us. We run Node 24.