run npm install in here
Don't analyze app.js before trying the task
Open app.js and modify HOW_OBVIOUS_THE_FLAME_GRAPH_SHOULD_BE_ON_SCALE_1_TO_100
It will affect how hard it is to find the function you're looking for.
| difficulty level | value |
|---|---|
| a month old baby would spot it | 100 |
| still easy | 30 |
| normal | 10 (default) |
| hard | 5 |
| please try normal first ;) | 1 |
Run the app through perf. Make the following request:
curl http://localhost:8080/api/tick
Or just open it in the browser.
Generate a flame graph, identify the function in your code that performs the long synchronous computation.
Now for something more realistic.
Start the app, open http://localhost:8080/ to simulate traffic (it repeatedly makes requests to /api/tick), run a short perf on the running process and generate a flame graph. See if you would identify the function under real traffic. Try with shorter sleep and lower profiling frequency too.