`make profile`

runs: node --prof app.js

creates: v8.log

(not human-readable. gibberish.)

`make profile-results`

runs: nprof v8.log

top-down: overview of the call stack; system vs application time (total vs nonlib).

bottom-up: "heavy" sections of code. indents underneath mean "called by." * means "optimized by v8"

Evaluate and improve the identified bottlenecks.

Repeat until performance meets requirements.

Web Apps have "special needs."

They're idle most of the time and only ramp up when a user makes a request. Running a blanket profile will hide bottlenecks with very high idle / system usage.

Instead, we turn on and off the profiler to measure only what's important: request handling.

https://github.com/bnoordhuis/node-profiler

I've added lib/profiler to the middleware stack. It ties profiling sessions to actual requests.

It's configurable in config.*.js:

{ profiler: true }