Utility Process Topologies

Electron’s utility process runs in a separate Node.js thread. You can connect it via MessagePort for offloading heavy computation.

Utility Worker

// utility-process.ts (runs in a utility process)
import { createParentPortHandler } from 'electron-messageport-trpc/utility';
import { utilityRouter } from './router';

createParentPortHandler({
  router: utilityRouter,
  parentPort: process.parentPort,
});

Main to Utility

// main process
import { createTRPCClient } from '@trpc/client';
import { MessageChannelMain, utilityProcess } from 'electron';
import { mainPortLink } from 'electron-messageport-trpc/main';

const child = utilityProcess.fork('utility-process.js');
const { port1, port2 } = new MessageChannelMain();

child.postMessage({ type: 'connect' }, [port1]);

const client = createTRPCClient({
  links: [mainPortLink({ port: port2 })],
});

Renderer to Utility

// main process broker
import { createPortBroker } from 'electron-messageport-trpc/main';
import { utilityProcess } from 'electron';

const child = utilityProcess.fork('utility-process.js');
const broker = createPortBroker();

win.webContents.on('did-finish-load', () => {
  const { serverPort } = broker.createRendererPort(win.webContents);
  child.postMessage({ type: 'connect' }, [serverPort]);
});

This keeps the main process out of the request path. It only creates and transfers the port pair.

Architecture

Renderer <== MessagePort ==> Main Process <== parentPort ==> Utility Process

Choosing a Topology

Topology	Use Case	Pros	Cons
Renderer to Main	Standard RPC, DB access, native APIs	Simple setup	Main process is the bottleneck
Main to Utility	Heavy computation, background tasks	Offloads main thread	Extra process overhead
Renderer to Utility	Direct offloading via broker	Keeps main out of the request path	Most complex setup