Monitoring Node.js: Watch Your Event Loop Lag!

Event loop lag is an essential, but often overlooked performance metric for Node.js applications. What is it and why does it matter?

David Hettler
Jan 14, 2020 · 9 min read

If you ask any Node.js developer for their number one performance tip chances are close to a hundred percent that they will give you the following advice:

Avoid synchronous work.

Why is synchronous work bad? Because in Node.js, there is only a single thread. If you keep that single…