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Starred by 4 users
Status: Assigned
Owner:
rajendrant@chromium.org
Cc:
rajendrant@chromium.org
sclit...@chromium.org
Components:
EstimatedDays: ----
NextAction: ----
OS: Mac
Pri: 2
Type: Bug



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Image LazyLoad flag enabled leads to 3x request count, multiple image downloads

Reported by doug.sil...@gmail.com, Aug 19 
UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3527.0 Safari/537.36

Steps to reproduce the problem:
1. load page with flag off, observe request count/ files downloaded in DevTools
2. enable the enable-lazy-image-loading flag (restart Canary)
3. Repeat one and compare the request count, and observe same image downlaoded multiple times

What is the expected behavior?
images above the fold downloaded first, and then images below the fold downloaded. Only one full download per file.

What went wrong?
Here are two websites I can reproduce the error on (one has lazyload="on" explicitly defined, the other does not)
https://dougsillars.github.io/indexllon.html
https://dougsillars.github.io/index-resp_qauto_fauto.html

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: 70.0.3527.0  Channel: canary
OS Version: OS X 10.13.3
Flash Version: 

Thanks!

Comment 1 by ksakamoto@chromium.org, Aug 20

Cc: rajendrant@chromium.org
Components: -Blink>Loader Blink>Loader>LazyLoad

Comment 2 by phanindra.mandapaka@chromium.org, Aug 20

Labels: Needs-Triage-M70

Comment 3 by sclit...@chromium.org, Aug 27

Cc: sclit...@chromium.org
Owner: rajendrant@chromium.org
Raj, could you take a look?

Comment 4 by doug.sil...@gmail.com, Sep 20 

This is improving. I see that there not as many requests, but for this page:

https://dougsillars.github.io/indexbg_opt.html
above the fold images are downloaded 2x.

Version 71.0.3557.0 (Official Build) canary (64-bit)

Comment 5 by tbansal@chromium.org, Sep 21

Status: Assigned (was: Unconfirmed)

Comment 6 by rajendrant@chromium.org, Sep 21 

hi Doug,

Yes. There will be 2x requests for above the fold images (and the images that are about to be visible, as the users scroll).

As you have mentioned in your blog post too, the first request will be small and only for the first 2KB. So it does not affect the total data downloaded, compared to the overall page size.
https://dougsillars.com/2018/09/21/chromes-experimental-image-lazy-loading-flag/

Comment 7 by doug.sil...@gmail.com, Sep 22 

Yes,

But in Canary desktop, I see the 206 for 2 KB, and then two full 200 requests for the entire image.

In my post, those highlighted requests in the figure are 200s.

Comment 8 by rajendrant@chromium.org, Oct 10 

Thanks Doug.
Let me check with Mac. It did not load two full 200 requests in linux desktop.

Comment 9 by e...@cloudinary.com, Nov 15 

Have you had a chance to check this out, rajendrant?

I can reproduce the issue on Chrome 72.0.3608.0 / Mac.
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