Hi all! After Bug 1377766 lands, we will increase the amount timeouts executing in background tabs are throttled, based on an execution budget. This budget is continuously regenerating, and is decreased when timeouts execute. If the budget becomes negative, timeouts will not be allowed to run until the budget is positive again. This punishes pages that behave poorly while not being in the foreground.
This feature has been developed behind "dom.timeout.enable_budget_timer_throttling". Other relevant prefs are: * dom.timeout.background_budget_regeneration_rate The rate of budget regeneration; the time in milliseconds that it takes to regenerate 1 millisecond * dom.timeout.background_throttling_max_budget The maximum budget. Budget is clamped to this. * dom.timeout.budget_throttling_max_delay Effectively the minimum budget. The maximum delay of a throttled timeout * dom.timeout.foreground_budget_regeneration_rate The same as the background variant, but for foreground tabs. Only applicable for testing. * dom.timeout.foreground_throttling_max_budget The same as the background variant, but for foreground tabs. Only applicable for testing. * dom.timeout.throttling_delay The amount of time we require to pass after a page has completely loaded until we start throttling. The default values of these prefs are: dom.timeout.background_budget_regeneration_rate: 100 dom.timeout.background_throttling_max_budget: 50 dom.timeout.budget_throttling_max_delay: 15000 dom.timeout.foreground_budget_regeneration_rate: 1 dom.timeout.foreground_throttling_max_budget: -1 dom.timeout.throttling_delay: 30000 This is read as: budget regenerates 10 ms per second and will never grow beyond 50 ms. If the execution budget is negative a timeout will not run until it becomes positive, which happens at the said rate, but it will also not be delayed more than 15 seconds. Throttling for foreground is effectively turned off. Throttling doesn't commence until after 30 seconds. Google has a similar feature[1] for timer throttling. Turning on this feature is tracked in Bug 1377766 [2] It is inherently difficult to test this feature without false negatives due to the timing dependency of the feature. Bug 1378402 tracks adding tests for testing throttling, but they suffer from being a bit too intermittent still. At least for debug builds. My hope by getting this in early in the release cycle is to be able to actively evaluate the feature, so I hope that you take the time to report those bugs! :) My hope is that this will land on Monday October 9th if there are no objections. Cheers, Andreas [1] https://developers.google.com/web/updates/2017/03/background_tabs#budget-based_background_timer_throttling [2] https://bugzilla.mozilla.org/show_bug.cgi?id=1377766 [3] https://bugzilla.mozilla.org/show_bug.cgi?id=1378402 _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
