1538364 - Consider firing the load/loadend/final readyState events for XHR later during page load (after page load event if possible)

Status: RESOLVED FIXED

(Core :: DOM: Networking, enhancement, P2)

Description

[Olli Pettay [:smaug][[e-mail]]]

Many pages use XHR during page load, and the final events for such end up firing during the load. That may affect page load time rather heavily.
https://hg.mozilla.org/try/rev/5b88b11dce7f2240bb0dba6a7ec442aa82b9c6a8 is not a well working patch, but just a quick hack to test how much XHR may affect.

Initial results with Gmail don't look too bad, and I can definitely see
the difference locally.
linux https://i.ibb.co/jVGgjs8/image.png
windows https://i.ibb.co/b6Wxh8N/image.png

GDocs and GSlides hero seem to be affected too (but we don't measure loadtime on those ??)
Doesn't seem to affect much to other tp6 sites.

Comment 1

[Olli Pettay [:smaug][[e-mail]]]

Attachment: xhr_during_load_v1.diff

Comment 2

[Olli Pettay [:smaug][[e-mail]]]

raptor: https://treeherder.mozilla.org/#/jobs?repo=try&revision=3f27a14b62a6ff8b56f2cb3ed375d3669b74d7a5
tests: https://treeherder.mozilla.org/#/jobs?repo=try&revision=91915ca6e5ff830103e90bc43ca56c2d1fe39fd3

Comment 3

[Olli Pettay [:smaug][[e-mail]]]

Attachment: xhr_during_load_v1.diff

And silly mistake fixed.

raptor: https://treeherder.mozilla.org/#/jobs?repo=try&revision=90cb3bfe8f8498a4a539664f69f569e2cda5a03b
tests: https://treeherder.mozilla.org/#/jobs?repo=try&revision=aebb1ada6fbc466682947da405c9a52f03189b8d

Comment 4

[Olli Pettay [:smaug][[e-mail]]]

We should do something similar to fetch() too, but that is still way less often used.

Comment 5

[Olli Pettay [:smaug][[e-mail]]]

Attachment: Bug 1538364 - Fire the load/loadend/final readyState events for XHR later during page load (after page load event if possible), r=baku

Comment 6

[Olli Pettay [:smaug][[e-mail]]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=2feafcf6e93163fc686e9550c7b659948cb9f6e8

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/c8d17bfeca07
Fire the load/loadend/final readyState events for XHR later during page load (after page load event if possible), r=baku

Comment 8

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/c8d17bfeca07

Comment 9

[Chris Peterson [:cpeterson]]

67=wontfix because I assume that XHR changes are too risky to uplift for Firefox/GeckoView 67 Beta (and Fenix MVP).

Comment 10

[Kohei Yoshino]

Posted site compatibility note: https://www.fxsitecompat.com/en-CA/docs/2019/xhr-load-loadend-readystatechange-events-are-now-deferred-during-page-load/