1634020 - Regular buffering and network inactivity on YouTube with http3

Status: RESOLVED WORKSFORME

(Core :: Networking: HTTP, defect, P2)

Description

[Chris Lane]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:75.0) Gecko/20100101 Firefox/75.0

Steps to reproduce:

Load any YouTube video with network.http.http3.enabled set to true in Firefox.

I also tested this on Chromium 81.0.4044.129 with the flags --enable-quic --quic-version=h3-25 where the issue does not occur.

Actual results:

The video will at points stop loading and then start loading again after around 30 seconds. This results in reaching the end of the video buffer and then having to wait a while for any more of the video to load.

This is occurring on a stable 150Mbps network.
Stats for nerds screenshot (Firefox): https://i.imgur.com/F9a1ccs.jpg
Stats for nerds screenshot (Chromium): https://i.imgur.com/BHQfF9A.jpg
Debug info (Firefox): https://gist.github.com/ChrisLane/621a50f8aa8bb491970a5cff7083285a
Debug info (Chromium): https://gist.github.com/ChrisLane/5aee3d2faf3af5c80e65d095e4348e82

Expected results:

Videos should load as fast as possible.

Comment 1

[Michal Novotny [:michal]]

I cannot reproduce it, but I'm using beta release. Could you try beta or nightly? http3 is still disabled by default and if you want to test it you should ideally use nightly release.

Comment 2

[Chris Lane]

The issue still occurs on Beta but it's not as bad, the buffer loads enough that the video can continue playing most of the time.

Beta nerd stats: https://i.imgur.com/baEUZYg.png
Beta debug info: https://gist.github.com/ChrisLane/4664e1617a1be102e20f9481a2ec45cf

The issue still occurs on Nightly, about the same as on Beta.
Nightly nerd stats: https://i.imgur.com/35hf4yG.png
Nightly debug info: https://gist.github.com/ChrisLane/9a1456a75f2f4aa32c5856f5ef5ec390

Both versions have drastically improved video loading before turning on http3.

Comment 3

[Chris Lane]

Realised that I didn't add a Firefox 75 without http3 nerd stats screenshot for comparison.
Here's that: https://i.imgur.com/vhswtDT.png

Comment 4

[Chris Lane]

System details:
Arch Linux 5.6.7
Wayland 1.18.0

Comment 5

[sjw]

I observed the same issue on Firefox Nightly, but it's hard to reproduce.

Comment 6

[Chris Peterson [:cpeterson]]

I see this problem, too. I think this bug is a duplicate of bug 1636479.

https://bugzilla.mozilla.org/show_bug.cgi?id=1636479#c13 says "The Google developers found out that this is a problem on their side. They are working on a fix."

Comment 7

[Dragana Damjanovic [:dragana]]

(In reply to Chris Peterson [:cpeterson] from comment #6)

I see this problem, too. I think this bug is a duplicate of bug 1636479.

https://bugzilla.mozilla.org/show_bug.cgi?id=1636479#c13 says "The Google developers found out that this is a problem on their side. They are working on a fix."

This bug is probably not a dup of 1636479 (as they said that youtube has a slightly different server implementation).
We have fix some problems with QUIC/HTTP3 in neqo. I am waiting for an update of neqo in m.-c. to see if the problem still exist.

Comment 8

[Andy Grover [:grover]]

My experience is that using HTTP/3 on youtube, at least for scrolling down, which loads more thumbnails, is that I get the spinning circle when the POST request to "browse" file is stalled. All GETs seem to be fine, and other POSTs to e.g. log_event seem to also complete quickly. I haven't been able to figure out what's special about the "browse" POSTs yet, though.

Comment 9

[Chris Lane]

I just tried to reproduce this issue again on Firefox 80.0.1 and was unable to do so. I'll keep http3 enabled for a while to see if anything changes.

Comment 10

[Dragana Damjanovic [:dragana]]

I will close it for now. If you see any issues please report back. Thanks!

Comment 11

[Chris Lane]

While the immediately obvious buffering issues have gone, I have disabled http3 on my browser again.
While http3 is enabled, I've noticed that youtube videos will stop and not do any buffering for a while in the middle of long videos.