1661849 - Firefox resolves dns for new tabs after a delay of 4-5 seconds.

Status: RESOLVED WORKSFORME

(Core :: Networking: DNS, defect)

Description

[shayan.yaseen0]

Attachment: Downloads-main.22437.moz_log

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:80.0) Gecko/20100101 Firefox/80.0

Steps to reproduce:

Open a site in new tab or open firefox.

Actual results:

New tabs do not start resolving/loading until 4-5 seconds , possibly due to waiting for some timeout.

Expected results:

The tabs should have started loading/resolving immediately .

Things I have tried.
0) Reinstalled my linux completely (and hence firefox)

1. Disabled dns over https
2. Disabled ipv6
3. Complete reinstall of firefox
4. Used with Vpn
5. Checked if multi cores are being used.
6. Checked with chrome which works normally on the same pc

Comment 1

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

In the logs you sent it seems you have esni turned on.
Can you please flip the network.security.esni.enabled pref to false and see if you still get this problem?

Thanks!

Comment 2

[shayan.yaseen0]

(In reply to Valentin Gosu [:valentin] (he/him) from comment #1)

In the logs you sent it seems you have esni turned on.
Can you please flip the network.security.esni.enabled pref to false and see if you still get this problem?

Thanks!

Yeah i already tried it, i even installed Ubuntu again and even without changing any default setting the bug is still reproducible. In fact i forgot to mention this , but I had encountered this exact problem some months ago (perhaps on version 68) so this is not some update related issue. Also on the Firefox's subreddit some other users have also encountered this bug.

If you are able to understand the log ,Could you please mention what is Firefox trying to do in those 4-5 seconds.

P.S To explain more properly if i click a link simultaneously one to continue in this tab and another in a new tab, the first one will load immediately but the second will pause for a few seconds before starting to load. With this information i am not even sure if this is a DNS issue or something else.

Comment 3

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

The problem with the logs is that they don't provide enough info to be sure.
The entire log spans around 5 seconds of activity. The lines that are related to DNS only cover about 0.1 seconds

first instance: 2020-08-28 22:07:31.814615 UTC - [Parent 22437: Socket Thread]: D/nsHostResolver Resolving host [example.com]<> type 0. [this=0x7fcb8027a820]
last instance: 2020-08-28 22:07:31.909260 UTC - [Parent 22437: TRR Background]: D/nsHostResolver nsHostResolver::CompleteLookupByType record 0x7fcb6bef91b0 calling back dns users

Without more info, I really can't tell what's going on. I would need more complete logs.
Could you try to reproduce again, and submit the logs ? Thanks!

Comment 4

[shayan.yaseen0]

I just checked and (fortunately) can't reproduce this bug now.Should i mark this issue as resolved?

Comment 5

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

Please reopen if you find you can reproduce it again and are able to record the logs.
Thanks again!