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Firefox/Features/50ms ASSERT: Difference between revisions
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{{FeatureStatus | |||
|Feature name=Understand when user interface feels laggy | |||
|Feature stage=Landed | |||
|Feature version=Firefox 6 | |||
|Feature health=OK | |||
|Feature status note=Core instrumentation landed. SDR: N SIR: N | |||
}} | |||
{{FeatureTeam | |||
|Feature feature manager=Dietrich Ayala | |||
|Feature security lead=Curtis Koenig | |||
|Feature qa lead=AndreiD | |||
|Feature additional members=ted (infrastructure lead) | |||
}} | |||
{{FeaturePageBody | |||
|Feature overview=Any time the user interface takes more than 50ms to respond to an action, the application will appear sluggish to the user. To determine how often this happens, and what parts of our code are frequent offenders, we should add the ability to detect when the main-thread event loop is delayed by more than 50ms and log it as an ASSERT. | |||
However, just an ASSERT does not tell developers *what caused* the delay. In order to be useful, we must provide the ability for developers to easily get information about what code is slow. | |||
There are generally two scenarios in which the browser UI is non-responsive. | |||
# When a direct action by the user causes the app to be non-responsive. For example, a menu option that executes an action synchronously, and takes >50ms to return. | |||
# When a background action blocks the event loop for >50ms, causing the whole app to be non-responsive. | |||
The goal of this project is to get developer visibility into both scenarios with easy-to-use tools. | |||
|Feature users and use cases=*provide insight to developers into what is causing the Firefox user interface to feel slow or unresponsive to users | |||
*identify high impact areas for UI responsiveness work | |||
|Feature requirements=*Does not affect performance in production or beta builds | |||
*Can be logged to screen or file | |||
*Logging has been added to all primary user interface events | |||
|Feature non-goals=*provide information to end-users about what is causing Firefox to feel slow or unresponsive | |||
*provide UI profiling | |||
*integration of responsiveness testing into Talos | |||
|Feature ux design=--[[User:Faaborg|Alex]] 20:16, 31 May 2011 (PDT): Here's a [http://people.mozilla.com/~faaborg/files/daf/eventVisualization.png possible UI for visualizing responsiveness]. Note that the 50ms ASSERT is for discrete actions, anything that is continuous would need to log when the responsiveness was higher than 16.6ms during the action. In the visualization these appear as lines instead of dots (scrolling, moving the window, etc.) | |||
|Feature security review=* No sec rev needed | |||
|Feature qa review=* No test plan needed | |||
|Feature implementation notes===== Next Steps ==== | |||
*Complete project definition (ETA: 2011/04/01, Beltzner, Complete) | |||
*Work with UX to identify 15 primary UI events (ETA: 2011/04/01, [http://j.mp/ihM1wc google doc], Dietrich, Complete) | |||
*Implement core instrumentation of event loop ({{bug|601268}}, Ted, Complete) | |||
*Investigate options for correlation of event loop delays with high and low level code (ETA: xxx, Ted, in progress) | |||
*Investigate methods of identifying slow front-end UI (ETA: 2011/05/06, Dietrich, in progress) | |||
*Identify and publish top 10 code points causing event loop delays (Ted) | |||
*Identify and publish top 10 slowest-responding primary UI pieces (Dietrich) | |||
*Publish the tools and methods developed in this project (Ted, Dietrich) | |||
==== Related Bugs & Dependencies ==== | |||
'''Tracking Bugs''' | |||
*{{bug|651580}} - main project tracking bug | |||
'''Related Bugs''' | |||
*{{bug|601268}} - adds "canary in a coal mine" instrumentation to nsThread.cpp (MOZ_CANARY) | |||
*{{bug|606574}} - add event loop responsiveness instrumentation (MOZ_INSTRUMENT_EVENT_LOOP_OUTPUT) | |||
*{{bug|653701}} - adds ability to dump JS function calls executed when non-responsiveness is detected | |||
*{{bug|653703}} - adds ability to hook into a profiler (eg Shark) when non-responsiveness is detected | |||
*{{bug|580055}} - log all JS function entry/exits | |||
'''Related Projects''' | |||
* [https://github.com/autonome/about-response About:Response] - add-on that tracks response time of browser features | |||
'''Related Documents''' | |||
* [https://wiki.mozilla.org/Fennec/Features/Gestures Fennec Gestures project] - lists a bunch of features identified | |||
}} | |||
{{FeatureInfo | |||
|Feature priority=P1 | |||
|Feature roadmap=User Experience | |||
|Feature list=Desktop | |||
|Feature engineering team=Desktop front-end | |||
}} | |||
{{FeatureTeamStatus | |||
|Feature products status=tbd | |||
|Feature engineering status=tbd | |||
|Feature security status=tbd | |||
|Feature privacy status=tbd | |||
|Feature localization status=tbd | |||
|Feature accessibility status=tbd | |||
|Feature qa status=tbd | |||
|Feature ux status=tbd | |||
}} | |||
== Other Documentation == | |||
*[http://www.useit.com/papers/responsetime.html Jakob Neilson's UseIt article on Response Time Limits for User Interfaces] | |||