Re: WebPerfWG call - July 21st 2022 @ 8am PT / 11am ET

Minutes are now available:

    Linked to from our WebPerf WG Agenda document
    Published to the web-performance Github meetings page
    ... and copied below:

Dan Shappir, Noam Helfman, Rafael Lebre, Alex N.Jose, Pat Meenan, Nic
Jansma, Yoav Weiss, Ian Clelland, Michal Mocny, Hao Liuk, Barry Pollard,
Amiya Gupta, Carine Bournez, Benjamin De Kosnik

Nic: Next meeting - August 4th 10am PT

.. TPAC is September 12-16

… Meeting on Mon, Tue, Thu, Fri

… WIP agenda

… Add yourself to the attendees list

… Still capturing what people want to talk about

… Please add proposals near the top

… Registration is now available - need to be a WG member or invited expert

… Planning on being a hybrid meeting

… Organizers purchased some remote-friendly equipment

Yoav: Unload beacon is heading toward an Origin Trial

… provide feedback at

MinutesBFCache restoration entry

Presentation recording

Ian: Short update.

… issue 182 on performance timeline

… Resolution was that we want a different entry type

… Tie them all together with the concept of navigation id

… Can bikeshed the name

… Want to encapsulate the timing of the page show event

… Looking for feedback on the API shape

… Are there additional fields we should capture?

Nic: What duration will be set in this case?

Ian: Defined on performance entry directly

Nic: So duration is from the start of the user-initiated navigation to the
end of the pageshow events being completed?

Hao: Defined as a performance entry, and the start time would be the
navigation start

Nic: Navigation ID - this would be the first use for this? Is it an auto
incrementing number? Unique ID?

Ian: Currently auto-incrementing number, starts with 1 for BFCache and SPA
navs in the future

… Point to be made that an unguessable token would be better. When we’d
introduce SPA navs, we don’t want to break people’s expectations.

… makes testing this more difficult

Nic: One thing seen in the field data, not every telemetry makes it to the

… incrementing beacon numbers can help us spot cases where telemetry is

… May be able to notice this otherwise, so may not be applicable

Michal: Does that increment across page loads?

Nic: yeah. Slightly different concept, but may be relevant.

Michal: Navigation ID is separate?

Ian: yeah

Nic: And other things link to this concept of navigation ID?

Ian: That’s the thinking. Allows you to tie entries together.

Nic: thinking through the duration - nice to have the breakdown of page
show. Any other interesting breakdowns we could expose here?

Ian: I suspect it’s mostly browser internal, there’s some delay involved in
retrieving the page from the cache that's unavoidable. From the start of
the navigation, there may also be the time required to process any pagehide
handlers on the previous page, which we certainly cannot expose.

Yoav: Regarding the entry’s name, it was an empty string (the first),
because there’s no way to meaningfully name one bfcache registration vs
another.  So we wouldn’t want to support getEntriesByName() at all

Ian: One other type that doesn’t have a name

Hao: If you do getEntriesByName in JS, you get no result. So we shouldn’t
implement it

Nic: Will we have getEntriesByNavigationId?

Ian: There was a proposed method. I should dig it up

Michal: useful solution for a question I had. If I care about event timing
but want to slice it by navigations. I’d have to go through all navigation.

… But just the first event with this navigation ID should be what I want.

… So I’d just want the filter

Yoav: Why won’t filters work?

Michal: I’d have to listen to every possible type of navigation entry in
order to do that.

Hao: So you’d have to know which navigation type incremented the navigation
ID counter?

Michal: if all I care about is event timing, and this event had a
navigation ID, I’d have to go back and find the thing. I’d have to build my
own timeline in parallel.

… But if a new tpe of navigation entry is added, my script becomes stale

… but getByNavigationId would help me

Yoav: answered my question

Ian: LCP spec says that LCP has an empty name

Nic: Layout shifts may be the same

Yoav: makes sense to not support getEntriesByName for them

Hao: tried it and it returns nothing

Nic: There’s the new navigate API, would that add entries to that?

Michal: wouldn’t by default. It’s a cleaner way to use the browser’s API,
but it won’t by default change the perf timeline

Ian: Talked to Domenic about this, and it’s outside of scope for the
navigation API

… We may leverage parts of the API to inform the heuristics for what
triggers an SPA navigation entry to be emitted, but that API doesn't
attempt to define what is and is not an SPA navigation.

Michal: Not all uses of the navigation API are guaranteed to be a soft

… the API makes it easier for frames to manage state. But that doesn’t mean
they are “navigations”

Nic: found the discussion

Michal: Any way that unload beacon should play together?

.. I guess I’m not sure how it works with BFCache

Ian: unload beacon triggers when the page is in BFCache and not coming back

.. so restoration would cancel the beacon’s timeout if set

Nic: And the page can choose to add to the pending beacon.

Ian: No direct interaction between them

Michal: For some of these things you may want to slice, but that’s a

- Nic

On Wed, Jul 20, 2022 at 9:00 PM Nic Jansma <> wrote:

> Hi everyone!
> On the agenda
> <>
> for our next call (July 21st @ 8am PT / 11am ET) we will discuss:
>    - TPAC 2022 WIP Agenda
>    - BFCache restoration entry
> * <>*
> The agenda is a little light, so if there are any other topics or issues
> that members are interested in discussing, please let us know.
> If you have additional items, please add them to the agenda
> <>
> .
> Join us <>!
> The presentations will be recorded and published online afterwards.
> See you soon!
> - Nic
> @NicJ

Received on Tuesday, 2 August 2022 17:10:07 UTC