Node.js新手求助：nodemon运行一段时间后突然失效

Hey there! Let's dig into why your Node.js/Express setup is throwing errors after running smoothly with nodemon for a few minutes. Since you only shared a snippet of your app.js, I'll cover the most common culprits and how to fix them:

1. Unhandled Async Errors or Memory Leaks #

If your routes or middleware include async operations (like database calls, API requests) that aren't properly error-handled, or if there's a memory leak (e.g., unclosed database connections, growing global variables), nodemon can crash after some time as resources get exhausted or uncaught errors pile up.

Fix Steps: #

• Wrap all async code in try/catch blocks (for async/await) or use .catch() for Promises to catch errors explicitly.
• Make sure to release resources (like database connections) after each request.
• Example of a properly handled home route:

  app.get('/', async (req, res) => {
    try {
      // Example async operation (e.g., fetching data from DB)
      const pageData = await fetchSomeData();
      res.render('index', { data: pageData });
    } catch (error) {
      console.error('Error in home route:', error);
      res.status(500).send('Oops, something went wrong!');
    }
  });
  

2. Nodemon File Watching Conflicts #

Nodemon might be monitoring too many files (like node_modules, log files that update frequently) which can cause unexpected restarts or crashes over time.

Fix Steps: #

• Create a nodemon.json file in your project root to exclude unnecessary files:

  {
    "ignore": ["node_modules/", "logs/", "*.log", "tmp/"]
  }
  

• Or start nodemon with the ignore flag directly:

  nodemon --ignore node_modules/ app.js
  

• Check if any files in your project are being modified continuously (like auto-generated logs) and add them to the ignore list.

3. Port Occupation or Unclosed Server Processes #

Sometimes, when nodemon restarts, the previous Express server process doesn't shut down completely. Over time, this leads to port conflicts or too many running processes, causing crashes.

Fix Steps: #

• Add code to your app.js to properly close the server when the process exits:

  const server = app.listen(3000, () => {
    console.log('Server up on http://localhost:3000');
  });
  
  // Handle graceful shutdown on Ctrl+C or process termination
  process.on('SIGINT', () => {
    server.close(() => {
      console.log('Server shut down gracefully');
      process.exit(0);
    });
  });
  
  process.on('SIGTERM', () => {
    server.close(() => {
      console.log('Server terminated');
      process.exit(0);
    });
  });
  

• If you get a "port already in use" error, kill the stuck process:
  • On Windows (GitBash): netstat -ano | findstr :3000 then taskkill /PID <pid> /F
  • On macOS/Linux: lsof -i :3000 then kill -9 <pid>

4. Incompatible Dependency Versions #

Sometimes, version mismatches between Express, Pug, or Nodemon can cause runtime errors that only show up after a few minutes of running.

Fix Steps: #

• Update your dependencies to their latest stable versions:

  npm update express pug nodemon
  

• If updates don't help, do a clean reinstall:

  rm -rf node_modules package-lock.json
  npm install
  

If none of these fixes work, share the full error message from GitBash and your complete app.js code—this will help pinpoint the exact issue!

内容的提问来源于stack exchange，提问作者jash patel