1234240 - There's a huge time gap between the end of page load and displaying error page if I detach tab in separate window while the page is still loading

Status: NEW

(Firefox :: Tabbed Browser, defect)

Description

[arni2033]

Attachment: screencast 1 - huge time gap between the end of page load and displaying error page.webm

>>>   My Info:   Win7_64, Nightly 46, 32bit, ID 20151221030239
STR:
1. Open new tab
2. Type "asdf.asdf" in urlbar without quotes, press Enter
3. While the url is loading (== no response from server?) detach tab in separate window
4. Wait until the loading is finished
5. Wait until error page is displayed

Result:       There's about 4 seconds between Steps 4 and 5 (sometimes)
Expectations: There should be no time gap (~0 seconds)

Notes:
 I chose "asdf.asdf" because it's a reliable url that always returns connection error.
 See also attachment 8700630 [details] for the case of bad internet connection.
 I'm not sure if this bug only occurs with error pages.
 This happens in e10s mode AND in non-e10s mode.

Comment 2

[Kanchan Kumari QA]

This defect is related to bug #1234229. Please see that defect as well. I have written some comments there. In this defect, I think user is concerned about lag between the error message that the firefox receives and rendering of this error message. This needs more research. That's why changing the status from "New" to "Unconfirmed"

Comment 3

[Kanchan Kumari QA]

Hello Reporter, I agree with the minor issue that you reported in bug #1234229. But as far as lag in page rendering is concerned as you reported in this issue, I am not able to duplicate. When I try to access an invalid URL (with incorrect host name as you mentioned asdf.asdf), Firefox tries to resolve the DNS and as soon as it times out due to DNS error, error page is displayed on the browser. Can you please attach some supporting information through which I may be able to duplicate the problem? May be you could try developer tools on the browser and send us some timing, which shows this lag problem.

I tried on both Nightly as well as released versions:

Name 	Firefox
Version 	46.0a1
Build ID 	20151225030207
User Agent 	Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:46.0) Gecko/20100101 Firefox/46.0

And

Name 	Firefox
Version 	43.0.1
Build ID 	20151216175450
User Agent 	Mozilla/5.0 (Windows NT 10.0; WOW64; rv:43.0) Gecko/20100101 Firefox/43.0

Comment 4

[arni2033]

Attachment: screencast 2 - firefox leaves wrong state when tries to fix domain after tab detach.webm

Judging by "screencast 2", Firefox incorrectly sets page status when starts loading 'fixed' domain (I'm referring to "fixup" feature: http://www-archive.mozilla.org/docs/end-user/domain-guessing.html)

Also, I used mozregression to find the first version that exposes this behavior. It's Nightly 2008-11-15, when "detach tab" feature just landed (bug 225680). Pushlog_url (from mozregression):
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=dc0e07e3d380&tochange=6b7faccfd305

@Kanchan Kumari: have you tested exactly "asdf.asdf" (2 domain levels) or some random invalid string, like you said in bug 1234229 comment 5? Domain guessing only works with 2 domain levels, not 3. For example, "asdf.asdf.asdf" won't cause domain guessing, and therefore - won't trigger this bug.
Have you seen domain guessing at work after Step 3?
I'm setting keyword "qawanted" for now: probably somebody else will be able to reproduce this.

Comment 5

[arni2033]

(In reply to Kanchan Kumari QA from comment #2)
> In this defect, I think user is concerned about lag between the error message that the firefox
> receives and rendering of this error message.
Please don't add anything in my expectations. It's clearly visible on screencasts: There's time gap when Firefox still resolves some DNS, and there's no error yet, but current tab displays "New tab".

(In reply to Kanchan Kumari QA from comment #3)
> But as far as lag in page rendering is concerned as you reported in this issue, I am not able to
> duplicate. When I try to access an invalid URL (with incorrect host name as you mentioned
> asdf.asdf), Firefox tries to resolve the DNS and as soon as it times out due to DNS error, error
> page is displayed on the browser.
You can't just say that you haven't reproduced and change status based on that WITHOUT even asking for additional information and instructions. Start from STR_2_detailed, and comment here (or email me if you don't want to spam here) if you haven't reproduced. Also, I expect some screencast from your side to verify that you do exactly what STR says. If you can't / have no time to / don't want to test this properly, put the status back to where it was. (I'm not asking for anything SUPERNATURAL here)

STR_2_detailed:
1. Open new tab
2. Type "asdf.asdf " in urlbar without quotes, press Enter
3. Once you see that status panel displays "Looking up asdf.asdf", immediately move tab to new window.
4. Wait until Firefox starts looking up www.asdf.asdf
5.(unnecessary) Wait until error page is displayed

AR:
 Step 3 - Firefox is resolving "asdf.asdf", and current tab displays "Connecting" and spinner
 Step 4 - Firefox is resolving "www.asdf.asdf", and tab displays "New tab" and no spinner (THE BUG)
 Step 5 - Firefox got an error while resolving DNS. Tab displays "Problem loading the page"
ER:
 Step 4 - Firefox should show "Connecting", because it still is resolving some DNS.

Comment 6

[Kanchan Kumari QA]

Attachment: QA_issueDuplicated.PNG

Hello Arni2033,
I was not able to reproduce the issue with my old profile using "asdf.asdf " earlier. In fact, even today I could not duplicate it using one of the existing profiles and this URL but I was able to duplicate it with several other invalid urls involving 2 domain levels like "mail.asbq", etc. However, when I retested it with a fresh profile, I was able to see the behavior that you reported even with "asdf.asdf" and other invalid dummy URLs with 2 domain levels. Attached is my screenshot.