1754264 - Changing network.preload to false breaks webpages

Status: RESOLVED WORKSFORME

(Web Compatibility :: Site Reports, defect, P2)

Description

[yokoffing]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:98.0) Gecko/20100101 Firefox/98.0

Steps to reproduce:

I've had two instances where pref("network.preload", false); causes the webpage to not load or crash.

1. https://graad.eu/ (see https://github.com/yokoffing/Better-Fox/issues/44)
2. https://www.mg.superesportes.com.br (see https://github.com/yokoffing/Better-Fox/issues/53)

Actual results:

Site either does not load properly or crashes altogether.

Expected results:

Site should still load properly.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::Networking' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.

Comment 2

[Dragana Damjanovic [:dragana]]

Greg, can you find someone to take a look?

Comment 3

[Kershaw Chang [:kershaw]]

I've tried to reproduce this locally. The first site https://graad.eu/ was loaded completely with network.preload disabled, so there might be something changed at the server side.

When I tried to load the second site https://www.mg.superesportes.com.br with network.preload disabled, I've seen that the tab hung and my CPU usage was 100%. After disabling javascript, the site can be loaded partially, so I think this is a site issue and I'd like to change the component to Web Compatibility.

Comment 4

[Karl Dubost💡 :karlcow]

We can try to diagnose. But if it creates a crash and Chrome/Safari in the same circumstances would not crash, it's definitely a Gecko Core issue.

Comment 5

[Kershaw Chang [:kershaw]]

(In reply to Karl Dubost💡 :karlcow from comment #4)

We can try to diagnose. But if it creates a crash and Chrome/Safari in the same circumstances would not crash, it's definitely a Gecko Core issue.

I don't know if there is a way to disable preload for Chrome/Safari, so it's probably not easy to test the behavior of Chrome/Safari under the same circumstances.

Comment 6

[Karl Dubost💡 :karlcow]

I didn't have a crash but the memory footprint keeps increasing even on an inactive window. 20 Mo by 20 Mo

This is a profile for graad.eu
https://share.firefox.dev/3sVqgiI
Another one with the project already loaded
https://share.firefox.dev/3h4m3U2

Comment 7

[Karl Dubost💡 :karlcow]

Once I'm closing the tab for graad.eu, I'm getting back the memory, but not everything.

Comment 8

[Karl Dubost💡 :karlcow]

Attachment: preload-js from the site

https://www.mg.superesportes.com.br

The second one has definitely issues with Network. 
https://share.firefox.dev/3h50Rxh
where resources seem to never finish loading. 

The second one really rely on preload in its code. 
So it runs into an infinite loop. 

`window.document.createElement("link").relList.supports("preload")` will return `false` when `pref("network.preload", false);`

Comment 9

[Karl Dubost💡 :karlcow]

I would recommend the reporter to contact the websites for having better fallbacks.

Comment 10

[yokoffing]

I've tried to reproduce this locally. The first site https://graad.eu/ was loaded completely with network.preload disabled, so there might be something changed at the server side.

The first site, https://graad.eu/, will load but the CSS is broken on the page with network.preload set to false.

Comment 11

[BugBot [:suhaib / :marco/ :calixte]]

The bug has a release status flag that shows some version of Firefox is affected, thus it will be considered confirmed.

Comment 12

[Raul Bucata]

Following the steps to reproduce, I was able to reproduce the issue on the second page https://www.mg.superesportes.com.b, where the page does not load and Nightly prompts an error message:

https://prnt.sc/2FNQjrAgf-1i

For the first page: https://graad.eu/, the CSS is indeed broken:

https://prnt.sc/cJVPOynbxaPO

This was observed with the pref network.preload set to FALSE

Tested with:

Browser / Version: Firefox Release 101.0.1 (64-bit)/ Firefox Nightly 103.0a1 (2022-06-22) (64-bit) /Microsoft Edge Version 102.0.1245.44 (Official build) (64-bit)
Operating System: Windows 10 PRO x64

Notes:

1. Reproducible regardless of the status of ETP.
2. Reproducible on the latest build of Firefox Nightly and Release.
3. Works as expected using Edge.

Comment 13

[BugBot [:suhaib / :marco/ :calixte]]

Since nightly and release are affected, beta will likely be affected too.
$For more information, please visit auto_nag documentation.

Comment 15

[Sky Schubert [:skyschub]]

If you disable a feature of the Web Platform, and then use a site that depends on said feature, then yes, it breaks. This isn't really anything we can work on.