Page MenuHomePhabricator

Investigate first visual change performance alert on emulated mobile
Closed, ResolvedPublic

Description

This is what it looks like, and the red line is Chrome 74 rolling out:

Screen Shot 2019-04-25 at 9.22.24 AM.png (662×996 px, 108 KB)
'

So it looks like there's a Chrome change that made the emulated test slower on mobile.

I updated on to Chrome 74 beta some time ago on WebPageReplay and no alerts where fired, but I went and looked at my other testing setup and indeed 74 changes something. I updated to 74 beta the 11th, there's a jump there in user timings.

Screen Shot 2019-04-25 at 9.26.09 AM.png (640×2 px, 237 KB)

In first visual change it's harder to see because the instance I'm using isn't super stable:

Screen Shot 2019-04-25 at 9.27.18 AM.png (1×1 px, 314 KB)

but I think we can see a jump there too.

This is most sure a Chrome issue, but I wanna understand why we didn't get a WebPageReplay alert, so I'll look into that too.

Event Timeline

We had the same thing on WebPageReplay too. I actually didn't pay attention to it since we had so unstable metrics on Desktop with 73 T220796

Screen Shot 2019-04-26 at 7.26.15 AM.png (964×1 px, 240 KB)

Since this is Chrome running in emulated mode, it's hard to say if it will affect users or not. At least know we know the reason for the increase.