How do you implement a custom IPC (Inter-Process Communication) system?

Question

Accepted Answer

**IPC** — communication between processes.

```javascript
const { fork } = require("child_process");

// Parent process
const child = fork("./worker.js");

// Send task to child
child.send({ type: "process", data: { input: "hello" } });

// Receive result
child.on("message", (msg) => {
    console.log("Result:", msg);
});

// Error handling
child.on("error", (err) => console.error("Worker error:", err));
child.on("exit", (code) => console.log("Worker exited:", code));

// worker.js
process.on("message", (msg) => {
    if (msg.type === "process") {
        const result = heavyComputation(msg.data.input);
        process.send({ type: "result", data: result });
    }
});
```

**SharedArrayBuffer (shared memory):**
```javascript
const { Worker, isMainThread, parentPort, workerData } = require("worker_threads");

if (isMainThread) {
    const shared = new SharedArrayBuffer(1024);
    const arr = new Int32Array(shared);
    arr[0] = 42;

const worker = new Worker(__filename, { workerData: shared });
    worker.on("message", () => console.log(arr[0])); // 100
} else {
    const arr = new Int32Array(workerData);
    arr[0] = 100;
    parentPort.postMessage("done");
}
```

Node.js: How do you implement a custom IPC (Inter-Process Communication) system?