[webkit-dev] setTimeout as browser speed throttle

David Hyatt hyatt at apple.com
Wed Oct 1 10:38:51 PDT 2008

I think we should be shooting for a target clamp value of 3-5ms.


On Oct 1, 2008, at 12:02 PM, Linus Upson wrote:

> We can use the histogram facility in chrome to collect data from a dev
> channel release. It should only take a few weeks to get good data.
> What exactly do we want to measure to settle on a value?
> Linus
> On Wed, Oct 1, 2008 at 2:34 AM, Maciej Stachowiak <mjs at apple.com>  
> wrote:
>> On Oct 1, 2008, at 1:24 AM, David Hyatt wrote:
>> On Oct 1, 2008, at 2:52 AM, Darin Fisher wrote:
>> I can appreciate that you aren't interested in revisiting this  
>> problem after
>> having resolved it finally by adding the clamp.  I believe you when  
>> you say
>> you had compelling evidence too.
>> We are interested in revisiting the problem or we wouldn't be  
>> suggesting a
>> new high resolution timer API.
>> I'm with Hyatt. The reason we are having this thread is precisely  
>> to revisit
>> the problem.
>> I don't know how clear I was in the previous email, but basically  
>> it can
>> take a lot of time before you see problems.  What happens is a site  
>> makes a
>> change, screws up and puts in an unintentional setTimeout loop, and  
>> then
>> they pwn the CPU of a browser with no clamp.  They don't discover  
>> it because
>> every browser has a pretty high clamp.  When we had these issues,  
>> they'd
>> basically crop up one site at a time every so often.  The good news  
>> is that
>> usually the sites would fix the problems, but the bad news is it  
>> could take
>> a while, and angry users would be switching to Firefox.
>> That is what I was alluding to when I said it took us 3.5 years to  
>> first
>> realize we had to add the clamp. The problems come and go, but they  
>> are
>> consistently a problem, and it can take a while to realize it.
>> However, the bug Mike cited seems to mention problems with the 1ms  
>> limit on
>> some real sites:
>> <http://code.google.com/p/chromium/issues/detail?id=792>. At least  
>> 5 sites
>> are mentioned, including nytimes.
>> I think we are converging on some good solutions (somewhat lower  
>> basic
>> clamp, new highres API) and I regret if this thread has felt  
>> hostile to
>> anyone.
>> Regards,
>> Maciej
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