How to get percentage_smooth using a prerecorded timeline json file

[Srinivas Kowtal]

Hello,

I have an uncommon question. So please bear with me.

I am interested in calculating the percentage_smooth of say a website like www.ebay.com before and after some modifications. The way run_benchmark works now is that it launches ebay, scrolls, and calculates smoothness. I wanted modify the website before the scroll begins. I tried putting break point in the smoothness_controller.py and in smoothness.py {one in telemetry\...\metric} and once it was hit modified the HTML of ebay {by opening DevTools} and restarted the benchmark. However, after restarting telemetry crashes indicating DevTools has crashed. Since I didn't know how to fix this crash or the timeout that results in telemetry due to the time it takes to edit the HTML file, I wanted to see if I can just extract the smoothness calculation code from rendering_stats.py and feed it the timeline json data directly {which would have been saved after running ebay independently without using telemetry}. However, the chain of data structures involved convinced me that I need to ask for help on this group. 

So my question is, how can I use the json file saved from timeline window and calculate the percentage_smooth value {it should match the calculation from timeline}? 

Regards

Srini

[Dave Tu]

Hi,

The metric computation is very sensitive to timing differences and I don't recommend trying to pull the code out and running it without Telemetry. Do you have another way to modify the HTML? Ideally you'd be able to use record_wpr to record two versions of the website - with and without the HTML changes. If you need to modify the website at runtime, you could try executing JavaScript inside the benchmark after page load to modify it.

Dave