- From: Noam Rosenthal <nrosenthal@google.com>
- Date: Tue, 2 May 2023 18:34:29 +0300
- To: "Jansma, Nic" <njansma@akamai.com>
- Cc: "public-web-perf@w3.org" <public-web-perf@w3.org>
- Message-ID: <CAGf_Md032Z+C66TFSLxn2vq4HB2h+b05ybGfOJ-7k7BLFjZmQw@mail.gmail.com>
On Tue, May 2, 2023 at 5:44 PM Jansma, Nic <njansma@akamai.com> wrote: > Hi Noam! > > > > In the boomerang.js library (and thus in mPulse RUM data), we use > LongTasks to generate an aggregate RUM *Long Task Time* (LTT) metric and > as an input to our *Time To Interactive* (TTI) metric. > > > > Looking at our data for today, about 13% of the page loads we see are > marked as fully "hidden", i.e. for as long as boomerang.js is loaded, the > page is backgrounded or minimized. It sounds like in those cases, we would > not get any LongTasks reported, and our TTI metric may not work (or would > report better-than-expected results). This could cause some shifts in > reported data once this version of Chrome is shipped, so we'd likely want > to document the change for our customers. > Understood. We are still experimenting with this. > > > One other thought – if LongTasks reporting would start/stop as a page > transitioned between visible and not (switching between tabs during page > load, for example), might it confuse analytics in other ways? For example > if RUM sees LongTasks for some time, then none, then sees LongTasks again, > etc – the periods of "hidden" may be reported as "smooth-sailing" where it > just wasn't generating any LongTasks data (where it would today). > > You'll see the "visibility-state" entry which would allow you to discern that that's the reason for seeing no long tasks! > > > We can adapt either way, i.e. we may consider disabling TTI calculation if > the page is transitioning multiple times between hidden/invisible. > Thanks for the input :) > > > Nic Jansma > > [image: cidimage001.png@01D68B7B.AE0304C0] > > he/him > +1.408.650.0848 x70848 <(408)%20650-0848> > > Akamai Technologies > 150 Broadway > Cambridge, MA 02142 > > > > > > *From: *Noam Rosenthal <nrosenthal@google.com> > *Date: *Monday, May 1, 2023 at 10:17 AM > *To: *"public-web-perf@w3.org" <public-web-perf@w3.org> > *Subject: *PSA: longtasks & hidden windows > *Resent-From: *<public-web-perf@w3.org> > *Resent-Date: *Monday, May 1, 2023 at 10:16 AM > > > > Hola webperfies > > I'm planning to introduce a change to the implementation of longtask > reporting in chrome, that would fix a few longtask-related issues, but > would introduce a new change in behavior: long tasks would only be reported > for visible windows. > > > > Bug: https://bugs.chromium.org/p/chromium/issues/detail?id=1441419 > <https://urldefense.com/v3/__https:/bugs.chromium.org/p/chromium/issues/detail?id=1441419__;!!GjvTz_vk!WWEbBtKVU30R4-R-tF9PLs5OrO2tUo0amdp91SRdCTB4IgpmqAPW0J31kNxOci4xMyQzKhYsO5nvmrdrcA$> > > CL (behind a flag): > https://chromium-review.googlesource.com/c/chromium/src/+/4495305 > <https://urldefense.com/v3/__https:/chromium-review.googlesource.com/c/chromium/src/*/4495305__;Kw!!GjvTz_vk!WWEbBtKVU30R4-R-tF9PLs5OrO2tUo0amdp91SRdCTB4IgpmqAPW0J31kNxOci4xMyQzKhYsO5kF7XrwGw$> > > > > Before moving forward with this, I'd like to surface this to the group and > see if anyone is relying on longtasks being reported to hidden windows > (e.g. minimized, background tab). > > > > Thoughts? Objections? 👍s? >
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Received on Tuesday, 2 May 2023 15:34:47 UTC