295864 - image rendering delay using XMLHttpRequest see gmail for example

Status: RESOLVED INVALID

(Core :: XML, defect)

Description

[finkchef]

User-Agent:       Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.8) Gecko/20050511 Firefox/1.0.4

There is an issue where using xmlhttprequest with a javascript frontend causes 
a delay in the rendering of images. For example, viewing an attached image in 
gmail using the default xmlhttprequest mode there is a delay. Using gmail set 
in regular html mode there is no delay.

Reproducible: Always

Steps to Reproduce:
1.Load an image on an xmlhttprequest based website
2.
3.

Actual Results:  
Delay in rendering of the image

Expected Results:  
Instant rendering of the image

Comment 1

[Peter van der Woude [:Peter6]]

Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.8b2) Gecko/20050527
Firefox/1.0+ ID:2005052711

I can confirm the massive delays with Gmail image rendering at times.
It doesn't happen all the time though

->NEW
(don't know which component core:?)

Comment 2

[James]

I can also confirm this bug. I was working on a redesign of a popular site using
xmlthttprequest with a js frontend. We have the same issue where there is a lag
on the first time loading of images which is not present in other browsers.

Initially we thought this was an issue in our code, but after multiple times
testing, we determined that it was an issue in Firefox.

To double check we ran some tests on gmail. All gmail image attachments in
firefox have a 1 second or so loading lag on first time viewing. The problem
occurs regardless of image size or filesize. This issue is not there if you
switch to "standard html" in gmail. 

Comment 3

[José Jeria]

Can anyone please attach a minimized testcase showing this issue?
https://bugzilla.mozilla.org/attachment.cgi?bugid=295864&action=enter

Comment 4

[finkchef]

Attachment: An example of the image loading delay in xmlhttprequest enabled pages

This video clearly shows the delay in gmail when using xmlhttprequest. The
cache in firefox was cleared before both examples. The first shows gmail using
xmlhttprequet. The second shows gmail in regular html mode. This was tested on
multiple machines in various parts in the US and on other xmlhttprequest based
sites with the same result.

Comment 5

[Boris Zbarsky [:bzbarsky]]

I don't quite understand why this bug was confirmed, to be frank -- it's lacking
basic things like a clear description of the problem and reasonable steps to
reproduce.  So does someone have a clear testcase here?  What do you mean by
"load an image"?  And what does "XMLHttpRequest based site" mean?  Sync or async?

I can think of two things offhand that could be going on here to make this
invalid, based on the answers to the above.

1)  If the image load attempts to start when all connections to the server are
tied up with async XMLHttpRequests, then the image load will have to wait until
a connection frees up.
2)  If the image load starts and is then followed by a bunch of sync
XMLHttpRequest loads, the image load won't complete until all the sync loads
complete.

Comment 6

[Martijn Wargers (dead)]

I don't understand what this bug is about.
I've never had massive delays with Gmail image rendering.
I don't think the example video does show anything unusual, IE6 is doing the
same, basically.

Comment 7

[Wayne Mery (:wsmwk)]

(In reply to comment #5)
> I don't quite understand why this bug was confirmed, to be frank -- it's
> lacking basic things like a clear description of the problem and reasonable 
> steps to reproduce. 

closing INVALID based on comment 5 and comment 6. (No response from reporter. I can't speak to Peter's propensity to confirm bugs)
please reopen if you feel bug is not invalid.