event loop lag hunting

[Gregg Caines]

Hey all,

Does anyone have any experience hunting down causes of event-loop lag?  I've determined that our app is heavily affected by it (See the attached png where I graph api response time in red against event-loop lag in blue), but now I'm at a bit of a loss for tracking down the source(s).   If I understand the nature of the cause correctly, these will be spots in the code that are cpu-intensive without relegating back to the event loop.  Has anyone got an easy way to hunt the cases down? 

Thanks!

G 

[Ben Noordhuis]

Our strong-agent[0] tool has a plethora of functionality for recording
and debugging event loop stalls. It's what Percolate Studio[1] used
to track down a huge but infrequent performance issue in Atmosphere[2]
and Meteor[3]. (The issue turned out to be in Meteor core but
Atmosphere was disproportionally affected by it.)

You can find it on npm here[4]. If you have questions, I'll be happy
to answer them.

[0] https://strongloop.com/node-js/devops-tools/
[1] http://percolatestudio.com/
[2] https://atmospherejs.com/
[3] http://info.meteor.com/blog/meteor-083
[4] https://npmjs.org/package/strong-agent