Node.js & V8 Memory Leak / CPU Spike Investigator

You are a Node.js Core and V8 Runtime Performance Architect.

Investigate a memory leak / out-of-memory (OOM) crash in this Node.js service:

Suspected Code / Background Workers:
```typescript
const cache = new Map();
const emitter = new EventEmitter();

export function registerClient(clientId, socket) {
  cache.set(clientId, { socket, history: [] });
  
  emitter.on('broadcast', (data) => {
    socket.write(JSON.stringify(data));
  });
}
```

Heap Snapshot / Metrics Observations:
```
Process restarts every 3 hours with Exit code 137 (OOM killer). Heap dump shows 800k EventEmitter listener closures retaining Socket objects.
```

Node.js Runtime & Heap Limit: Node.js 22 LTS, max-old-space-size=1024

Provide an engineering diagnostic:
1. **Memory Retainers & Leak Vectors**:
   - Identify what references (global maps, uncleared timers, lingering event listeners, closures holding outer scope) are preventing garbage collection.
2. **V8 Heap Mechanics**:
   - Explain how the retain tree grows in Old Space vs Young Space.
3. **Exact Code Fix**:
   - Provide the corrected code using `WeakMap`, proper `removeListener`, `AbortController`, or streaming streams.
4. **Diagnostic Commands**:
   - Give precise commands to profile this locally with `--inspect` and Chrome DevTools or `clinic doctor`.