Android - Wakelock detector


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This presentation explains about the Wakelock feature of Android OS. It summarizes the good and negative effects of Wakelock to Android users.

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Android - Wakelock detector

  1. 1. Guide for Wakelock detector 1.5.* UzumApps Copyright 2013
  2. 2. What is wakelock? Wakelock is the Android feature which can be used by apps to override deep sleep and control power management of device: ● Keep CPU awake (at high frequency) ● Turn on the screen ● Keep the screen on Like in any other portable device when there is no User Interaction, the device enters into deep sleep mode, in which it uses the minimum power to prolong battery life. Usually, before entering into deep sleep mode: ○ First screen dims ○ Then screen turns off ○ Finally, CPU switches to the lowest frequency (sleeps)
  3. 3. Why wakelock is bad? ● Wakelock enables apps to do tasks transparently in the background, without user's awareness. Which might waste battery power, network data and other resources. ● Apps can switch on the screen without user's intention. This can be quite annoying for the users. ● Buggy apps; Whenever the wakelock is acquired, it must be released, otherwise it can cause sleepless (insomniac) phone. The phone's CPU keeps running or the screen won't turn off
  4. 4. Who benefits from WakeLock Detector(WLD)? ● People who suffer from extreme battery drain, even when they are not using phone (this is caused by CPU wakelocks) ● People who are annoyed by random Screen wake-ups (this one is caused by screen-wakelocks) ● People who don’t know which app is keeping their screen on continuously (this one caused by unreleased wakelocks)
  5. 5. Technical Knowledge: Wakelock Types in Android System Android PowerManager supports 4 kind of wakelocks for developers, which are used in acquire/release method : Wakelock Type CPU Screen Keyboard PARTIAL_WAKE_LOCK On* Off Off SCREEN_DIM_WAKE_LOCK On Dim Off SCREEN_BRIGHT_WAKE_LOCK On Bright Off FULL_WAKE_LOCK On Bright Bright Note: ○ PARTIAL_WAKE_LOCK must be released by developer after acquiring, otherwise it causes sleepless mode ○ Other wakelock types(screen related wakelocks) are released automatically when the user presses Power Button ○ By using ACQUIRE_CAUSES_WAKE_UP flag developers can turn on the screen while acquiring one of above wakelock types
  6. 6. Wakelock types in WLD To simplify the types of wakelocks “Wakelock detector” combines them into 2 types: ● CPU wakelocks ○ PARTIAL_WAKE_LOCK ● Screen wakelocks ○ SCREEN_DIM_WAKELOCK ○ SCREEN_BRIGHT_WAKELOCK ○ FULL_WAKELOCK
  7. 7. What is “Wakeup triggers” In Android, there is a feature called “AlarmManager” which can be used by other apps to schedule periodic tasks (e.g: Facebook schedules a task that checks for new events every 5 minutes). This causes the phone to wake-up from its deep sleep mode for certain period of time. “Wakeup triggers” shows those apps which triggered the periodic tasks. It shows the exact amount of how many times the phone has been awaken by the app. By reducing these wakeups the battery life will be prolonged significantly (e.g: Reduce update(refresh) rate of Weather widgets..)
  8. 8. Since when wakelock statistics in WLD is shown The Battery management service of Android resets (nullifies) accumulated battery statistics (including wakelock statistics) in two cases: ● while rebooting phone ● when the phone is unplugged with battery level above 90% In Wakelock detector you can see statistics either since the time when it was reset or since the time when you unplugged the cable. If you choose “since unplug” then you have shorter duration but more sophisticated wakelock statistics shown.
  9. 9. Fin Thank you! Download Wakelock Detector at
  10. 10. Before sleep Sunday night: 50% should be enough until tomorrow morning ZZZ morning... Motivations for WLD
  11. 11. Motivations for WLD 4:00 AM zzzz screen turns on.. Ads Some new message?
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