Bug 9632 – [Drosera] syntax highlighting is slow (reproducible 40 second hang)

• Component: New Bugs
• Status: CLOSED FIXED

[Gavin Sherlock]

Launch Webkit (SVN 15070)
Launch Drosera, and attach to Webkit
In Webkit, go to http://nightly.webkit.org/

In Drosera, code from http://www.google-analytics.com/urchin.js will show up
Use the drop down menu in Drosera to switch to looking at the source for http://nightly.webkit.org/
Drosera will now hang for ~40 seconds while rendering the source

[Timothy Hatcher]

This is our syntax highlighting, soon to be done in the engine at top speed.

[Timothy Hatcher]

I can't reproduce on the nightly page, but this is very bad on yahoo.com. I have a fix.

[Timothy Hatcher]

Created attachment 9826 [details]
Proposed fix

Do not change the file source when normalizing the line endings. We use this file source to compare against new versions of the source as it comes in, so we can skip re-syntax highlighting if they are the same. The problem apparent on yahoo.com since they have mixed line endings and once we normalize them the source will always be different. This was compounded by the fact that yahoo has around 40 inline scripts. Each inline script causes us to check if the main document has more loaded, that is when we compare the source strings. Since they are always different we would syntax highlight yahoo.com 40 times! We do check source length before doing a more expensive string comparison, but the lengths were the same.

* Drosera/debugger.js:

[Timothy Hatcher]

Note: syntax highlight is still slow, but not 40 seconds. It is down to around 2-8 seconds for Yahoo.com depending on the computer speed. Syntax highlighting should be done in the engine, for maximum speed. See bug 10217.

[Darin Adler]

Comment on attachment 9826 [details]
Proposed fix

r=me

[Timothy Hatcher]

Landed in r15762

[Timothy Hatcher]

Closing since Drosera has been replaced by the new Web Inspector debugger. Moving to the New Bugs component so the Drosera component can be closed and removed.