Measuring and monitoring Node.JS server performance [closed]

Answer 1

I recommend monitoring your event loop and if it starts to back up more than 200ms on a regular basis, you'll need to scale.

Answer 2

As @ThiefMaster said, this depends on your system. You need to monitor the requests for your site, the CPU load, memory footprint etc and decide if and when to add mode servers.

If you want to know more about Node.js performance read this good article: http://blog.3rd-eden.com/post/5809079469/theoretical-node-js-real-time-performance

If you need a Node.js metrics library, there are 2 ones which I can recommend:
https://github.com/felixge/node-measured
https://github.com/mikejihbe/metrics

Resources:

monitoring a node.js server