1555878 - Firefox performed poorly when rendering pages that contain masking image

Status: NEW

(Core :: Graphics: ImageLib, defect, P3)

Description

[tungweic]

Attachment: index.html

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:67.0) Gecko/20100101 Firefox/67.0

Steps to reproduce:

1. Open index.html
2. Click Load button
3. Observe each individual page is rendered slowly

Actual results:

The pages are loaded and rendered slowly.

Expected results:

The pages should be loaded and rendered faster since the pdf file is just 1.2 MB.

Comment 1

[tungweic]

Attachment: imagefill.pdf

Added the pdf file for repro.

Comment 2

[tungweic]

For verifying the bug, put index.html and imagefill.pdf in the same web directory and follow the steps to reproduce.

Comment 3

[Trevor Rowbotham [:rowbot]]

Performance profile: https://perfht.ml/2W7NFL9

Comment 4

[Lee Salzman [:lsalzman]]

The profile looks like it is showing just a lot of time spent in codecs to decode the embedded jpegs and such. Andrew?

Comment 5

[Andrew Osmond [:aosmond] (he/him)]

This is a flaw in our sync decoding logic. Small images may be sync decoded as it will be fast. If we request in a loop many many small images to be decoded, it will sync decode them all. It should probably have a maximum budget which we can reset on a timer, and if we exceed the budget, we always async decode. We already track the time to decode in Decoder::mDecodeTime; ideally we would even sample this time for images that did not finish decoding due to missing data from the network.

Comment 6

[BugBot [:suhaib / :marco]]

The component has been changed since the priority was decided, so we're resetting it.
For more information, please visit auto_nag documentation.