- From: Boris Zbarsky <bzbarsky@MIT.EDU>
- Date: Wed, 27 Jul 2011 02:04:42 -0400
- To: public-web-perf@w3.org
On 7/27/11 1:23 AM, James Robinson wrote: > The one point of potential interest or controversy is the expected > callback behavior for background tabs. The processing model I've > specified says that callbacks do not fire at all when a document is > hidden I'd like to reiterate that I don't think this is acceptable unless _all_ web platform animation-related callbacks (SMIL, CSS transitions, CSS animations, etc) have that as an acceptable behavior. > We've discussed this a few times on the list before and absent any new > data I think that not firing callbacks is a better default behavior for > users since it uses the least CPU for background content. Of course. But that's not the only consideration here; API and platform consistency as well as existing author expectations need to be factored in too. > We can revisit this if we get any new data, for example if we find evidence of > compatibility issues with suppressing the callbacks completely. We have compatibility issues right now, even with just the backoff behavior Firefox has. For example, sites that use jQuery animations to move things off an interval timer go completely haywire if you stick them in a background tab for a bit in current Firefox or Chrome, and the effect is somewhat worse in Chrome due to the fact that it completely pauses the callbacks. See http://api.jquery.com/animate/#notes-0 second bullet point -- sites violate the advice of that note all the time; we've had at least 3 separate bug reports on Firefox about it so far that I've seen. It's enough of a problem that I've been seriously considering switching back from the exponential backoff we do now to some fixed but slow heartbeat rate. -Boris
Received on Wednesday, 27 July 2011 06:05:25 UTC