Testing, Performance & Deployment

Node.js Graceful Shutdown

A graceful shutdown stops accepting new connections, lets in-flight requests finish, closes database connections, and only then exits — so a deploy or restart does not drop live requests.

What is Graceful Shutdown in Node.js?

A graceful shutdown stops accepting new connections, lets in-flight requests finish, closes database connections, and only then exits — so a deploy or restart does not drop live requests.

Graceful Shutdown example

Handling SIGTERM correctly

JavaScript

const server = app.listen(config.port);

async function shutdown(signal) {
  logger.info({ signal }, 'shutting down');

  server.close(async () => {          // stop accepting new connections
    try {
      await mongoose.connection.close();
      await redis.quit();
      logger.info('closed cleanly');
      process.exit(0);
    } catch (err) {
      logger.error({ err }, 'error during shutdown');
      process.exit(1);
    }
  });

  // do not hang forever if something refuses to close
  setTimeout(() => {
    logger.error('forced shutdown after timeout');
    process.exit(1);
  }, 10_000).unref();
}

process.on('SIGTERM', () => shutdown('SIGTERM'));
process.on('SIGINT', () => shutdown('SIGINT'));

Key points to remember

Docker, Kubernetes and PM2 all send SIGTERM before killing a process.
Always include a forced-exit timer — a stuck connection should not block the deploy.
unref() on that timer lets the process exit early if shutdown finishes first.

Common mistakes with Graceful Shutdown

No SIGTERM handler, so every deploy drops in-flight requests.
Calling process.exit() immediately, truncating responses and pending writes.

Node.js Graceful Shutdown— Interview Questions & FAQs

Why do requests fail during deployment?+

The process is killed while requests are in flight. Handle SIGTERM, call server.close() to stop accepting new connections, wait for existing ones to finish, then exit.