952909 - With a very large canvas, getImageData() may hang Firefox

Status: RESOLVED WORKSFORME

(Core :: Graphics: Canvas2D, defect)

Description

[Tim Guan-tin Chien [:timdream] (please needinfo)]

Attachment: big-image-data.html

Tested on the latest FirefoxNightly on Mac.

STR:

1. Go to the attached test case and hit run()

Expected:

1. The page prints "Start ... Finished", or maybe,
2. If the process takes too long, the runaway timer should kick in and allow user to abort the script.

Actual:

1a. The browser hangs (seemly) indefinitely, and if e10s is enabled,
1b. The tab hangs.

Note:

1. The test case creates a very large canvas, draw some text on it, and call getImageData().
2. It was first reported by :lafncow on https://github.com/timdream/wordcloud2.js/issues/14, and we traceback to the browser bug here. The test case is derived from the library.
3. On Chrome the tab will crash right away, arguably a "better" experience :P.

Setting "critical" because the bug will cause user lost all the tabs and only make users to regain them through session restore.

Comment 1

[Chris Peterson [:cpeterson]]

This bug affects Shumway, too. cwahler created a jsperf test demonstrating the performance problem:

http://jsperf.com/cwahlers-getimagedata/2

Comment 2

[Chris Peterson [:cpeterson]]

This perf problem is not e10s-related.

Comment 3

[Jet Villegas (inactive)]

In the benchmark, the elapsed time for getting/putting a fixed 100x100 bitmap increases as the canvas size increases. We expect that the cost of reading/writing fixed source/destination regions would be constant regardless of the canvas size.

Comment 4

[Jet Villegas (inactive)]

GFx team requested we move the perf issue to bug 1001069 so we keep the crasher separate.

Comment 5

[BugBot [:suhaib / :marco/ :calixte]]

In the process of migrating remaining bugs to the new severity system, the severity for this bug cannot be automatically determined. Please retriage this bug using the new severity system.

Comment 6

[Chris Peterson [:cpeterson]]

Resolving WORKSFORME because the attached test case doesn't hang the browser in 107.