672064 - twitter-text.js is slow to load in Firefox

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Robert Sayre]

I was playing around with this file this morning and noticed that the latency was really bad in Firefox 5 and 8. I narrowed it down to the time need to create a bunch of regular expressions. Will attach a testcase. Here are the times:

Firefox 8:      1450ms
WebKit Nightly: 150ms
Chrome 12:      20ms

Since we're sharing a regex implementation with WebKit, I am puzzled by the disparity here. Perhaps we are eagerly compiling each regex and they are doing so lazily. I ruled out network traffic by placing timers directly in the source (attached test is different, so as not to perturb the original file).

Comment 1

[Robert Sayre]

Attachment: jquery dependency

Comment 2

[Robert Sayre]

Attachment: twitter-text.js

Comment 3

[Robert Sayre]

Attachment: Test case

Comment 4

[Robert Sayre]

Source repo is here:

https://github.com/twitter/twitter-text-js

Poking around twitter.com, I see that this file does get used, albeit an earlier version with fewer regexes to run. 

(Also CCing oliver@apple in case he wants to file a bug on JSC being an order of magnitude slower than V8 here)

Comment 5

[Oliver Hunt]

https://bugs.webkit.org/show_bug.cgi?id=64652

Comment 6

[Robert Sayre]

https://gist.github.com/1086653

Here's a patch that speeds up the load in all browsers, in the WebKit bug Oliver points out that I didn't Shark it yet so it could be something else.

Comment 7

[Robert Sayre]

The issue was a really long regex. They fixed it on another branch by using character ranges instead.

https://github.com/twitter/twitter-text-js/commit/672cf1b17069712cb3a674c73f8a92b21669ac1b

Comment 8

[Robert Sayre]

er, that should be

https://github.com/twitter/twitter-text-js/commit/e7a123d8da2e8efbf808d672acf43835fb356736#diff-1

Comment 9

[Timothy Nikkel (:tnikkel)]

673274

Comment 10

[Chris Leary [:cdleary] (not checking bugmail)]

Making the dependency more specific. Note the reduction in bug 673188 comment 35.

Comment 11

[Chris Leary [:cdleary] (not checking bugmail)]

HTML test case shows 9ms in nightlies for me.