134149 - CPU usage 100% when visiting http://www.omroep.nl/nos/nieuws/index.html

Status: RESOLVED DUPLICATE of bug 123273

(Core :: DOM: Core & HTML, defect)

Description

[Eric de Redelijkheid]

CPU usage jumps to and remains at 100% when visiting
http://www.omroep.nl/nos/nieuws/index.html

Closing the tab/window reduces CPU load immediately.

Comment 1

[Eric de Redelijkheid]

Build 2002031104 (0.99 milestone) Windows NT

Comment 2

[Arthur]

Confirming on linux 2002032808. Disabling JavaScript makes the CPU usage drop a
lot. I'd say the news ticker is a bit CPU greedy.

Comment 3

[Boris Zbarsky [:bzbarsky]]

We need a profile here... 

Comment 4

[Arthur]

Tried to profile it JS Debugger but I keep crashing or hanging -> bug 134377.
Changing URL, it's definitly the news-ticker.

Is there a step by step recipe on how to make a JS-Profile?

Comment 5

[Arthur]

.

Comment 6

[Arthur]

The right URL for real this time, sorry for the spam.

Comment 7

[Richard Godbee]

The news ticker is indeed the problem.  The JavaScript on that page boils down to:

  function doSomething() { /* do stuff */ setTimeout('doSomething()', 0); }
  doSomething();

doSomething() is called, which uses setTimeout() to call doSomething() again in
0 milliseconds.  Then that doSomething() calls doSomething() in 0 milliseconds.
 And on and on.

Mozilla is working like I would expect it to -- the JavaScript interpreter tries
calling doSomething() as often as possible, causing it to eat all available CPU
time.  If this behavior is undesirable, the JavaScript interpreter should impose
a minimum value on the 2nd argument to setTimeout().  In my testing, changing
the above code to use a delay of 1 cut CPU usage in half.

Comment 8

[Richard Godbee]

This is a duplicate of bug 123273.  (Sorry for the spam -- didn't realize it was
a dupe until well after I added my previous comment.)

Comment 9

[Boris Zbarsky [:bzbarsky]]

So it is.  :)

*** This bug has been marked as a duplicate of 123273 ***