1618200 - No UI option to turn off "Race Cache With Network"

Status: UNCONFIRMED

(Core :: Networking: Cache, enhancement, P3)

Description

[unterholzer.gabriel]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:73.0) Gecko/20100101 Firefox/73.0

Steps to reproduce:

Firefox makes simultaneous requests against disk cache and network called "Race Cache With Network" (RCWN)
This can cause issues in countries that don't offer unlimited data plans (mostly affects developing countries where data is expensive), as more data than necessary is consumed to display a web page.

Actual results:

If you visited a webpage in the past, usually most of the web page data is stored in your cache on your disk. RCWN, however, causes the browser to query the network again, even if cache data is available, if the disk does not respond fast enough, which causes additional data being consumed.

Expected results:

There should be a UI option (apart from about:config's "network.http.rcwn.enabled") to turn off RCWN easily to conserve data. This could decrease costs for internet for people in developing countries and even for mobile users, where it is still very common to have limited data plans.
I'm fully aware about the thoughts behind RCNW, as it increases browsing speed, but in my opinion, speed is not always preferable, when it goes along with higher costs for networking.

Comment 1

[unterholzer.gabriel]

Maybe this addition is helpful to understand my issue:

In my home country, Austria, RCWN has never bothered me as I had an unlimited data plan and therefore was pleased to get fast loading webpages.
But now, I moved to a country without unlimited data plans (Ghana, 40GB per month, 120GHC, approx. 20€, approx. 22USD) and I'm greatly concerned about possibly many users having their data plans eaten because of a slight enhancement of their browsing speed.

Comment 2

[Michal Novotny [:michal]]

RCWN is disabled when phone uses mobile data. You can check the current status of RCWN using page about:networking#rcwn

Comment 3

[Valentin Gosu [:valentin] (he/him)]

We also don't race for resources larger than 256kb because that's unlikely to improve performance; and we only do it when we detect the disk cache is very slow.
Overall, RCWN should not consume too much bandwidth. I guess some telemetry for how much extra we use would be useful.

Comment 4

[unterholzer.gabriel]

Attachment: open.spotify.com_Archive [20-03-03 10-21-29].har

Comment 5

[unterholzer.gabriel]

Attachment: open.spotify.com_Archive [20-03-03 10-21-29].ods

Comment 6

[unterholzer.gabriel]

Attachment: www.derstandard.at_Archive [20-03-03 10-26-14].har

Comment 7

[unterholzer.gabriel]

Attachment: www.derstandard.at_Archive [20-03-03 10-26-14].ods

Comment 8

[unterholzer.gabriel]

Thanks for the answer! I uploaded two examples of websites I access frequently and exported the HAR. Unfortunately it seems that information, whether a request was raced or not, is lost in HAR, so I also included an OpenOffice sheet with all raced calls for each HAR, where I put data manually from network panel.

www.derstandard.at: 222,04 KB of additional data used
open.spotify.com: 534,92 KB of additional data used

Considering I only requested two webpages, 756.96 KB is quite a considerable amount of data spent.

My device is a Lenovo Thinkpad T420s with an Intel SSD (SATA3) installed, so disk cache performance shouldn't be an issue in my opinion. It would be even more interesting to test this on a device with a normal hard drive, maybe RCWN has an even greater impact. Unfortunately there is no device with a normal hard disk around, so I can't test it.

Comment 9

[Damian Yerrick]

"Mobile data" is not the only layer 1 environment with data transfer quotas. Satellite and fixed LTE tend to have quotas as well.

Nor are data transfer overage fees the only undesirable outcome of RCWN. It can look like a SYN flood attack to a web server, which has been seen in bug 1622859 to trigger countermeasures that interrupt a user's access to a particular website.