> ## Documentation Index
> Fetch the complete documentation index at: https://braintrust.dev/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Debug hanging eval processes with external dependencies

export const plans_0 = "Any"

export const deployments_0 = "Braintrust-hosted, Self-hosted"

export const data_plane_version_0 = undefined

export const use_case_0 = "Use case - Evals using TypeScript SDK with external dependencies (databases, message queues, caching layers)"

<Note>
  **Applies to:**

  * Plan - {plans_0}
  * Deployment - {deployments_0}
  * {data_plane_version_0}
  * {use_case_0}
</Note>

## Summary

**Issue:** Node.js process hangs indefinitely after `braintrust eval` completes successfully, preventing the process from exiting. The eval finishes but the CLI appears frozen with no output or error messages.

**Cause:** External dependencies (database connection pools, persistent connections, WebSocket clients) keep the Node.js event loop active after eval completion.

**Resolution:** Identify blocking dependencies using Node.js debugger and explicitly close all external connections after eval completion, or use in-memory alternatives during evals.

## Resolution Steps

### Step 1: Identify the blocking dependency

Run your eval with Node.js inspector to identify which module prevents process exit.

```bash theme={"theme":{"light":"github-light","dark":"github-dark-dimmed"}}
node --inspect-brk ./node_modules/.bin/braintrust eval your-eval.ts

```

Open `chrome://inspect`, pause execution when the process hangs, and check the call stack for active connections.

### Step 2: Close external connections after eval completion

Explicitly close all database connections, clients, and persistent resources in your eval code.

```javascript theme={"theme":{"light":"github-light","dark":"github-dark-dimmed"}}
import { Eval } from "braintrust";
import { MongoClient } from "mongodb";

const client = new MongoClient(process.env.MONGODB_URI);

Eval("my-eval", {
  data: async () => {
    await client.connect();
    // ... eval logic
    return data;
  },
  task: async (input) => {
    // ... task logic
  },
  scores: [/* ... */],
});

// Close connections after eval
process.on('beforeExit', async () => {
  await client.close();
});

```

### Alternative: Use in-memory implementations during evals

Replace blocking integrations with in-memory alternatives to avoid connection pool issues.

```javascript theme={"theme":{"light":"github-light","dark":"github-dark-dimmed"}}
const memoryStore = process.env.IS_EVAL
  ? new InMemoryStore()
  : new MongoDBStore(client);

```

### Step 3: Common culprits to check

Verify these dependencies are properly closed:

* MongoDB connection pools: `client.close()`
* Redis clients: `redis.disconnect()`
* PostgreSQL/MySQL pools: `pool.end()`
* WebSocket connections: `ws.close()`
* HTTP keep-alive agents: `agent.destroy()`