How To Wake Up Sleeping Apps On Galaxy S9 Plus

Samsung

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Despite Android team promise to enforce OEMs to be transparent about non-standard app killing, in Android 11 Samsung has introduced a new severe (default ON) restriction. Apps can no longer hold wake lock in foreground services. This breaks many use-cases, for instance health apps are now unable to gather sensoric data for their users. See details here and read below for workaround.

UPDATE 04/2021: Is Samsung now killing even foreground services? Could this be real, or is it a chimera?
Even disabling the system battery restrictions does not save the app from being killed. Let's find out, if it is a bug or a feature... Here you can read more details

We record significantly increased number of app killing on Samsung's since Android Pie flavor. The hints show adaptive battery being much more eager than in stock Android.
After 3 days any unused app will not be able to start from background (e.g. alarms will not work anymore). Imagine, you won't use your alarm clock for the weekend plus 1 day and bang! no alarms anymore and you miss work! We strongly suggest to turn off Adaptive battery and Put apps to sleep options per instructions below.

Important: The latest feedback suggests even when you remove an app from the restricted list, Samsung may re-add them later after a firmware update or when it thinks it is using too much resources!

Yes, Samsung - a dominant vendor in the Android market - is now using one of the nastiest battery saving techniques in the industry. They kill background processes and render alarm clocks and other apps which rely on background processing useless. See below for workarounds.

NOTE: It is very hard to keep up with all the changes in the system settings layout and their modifications across all the combinations of phones and Android versions. If you find a different layout, or different name, let us know.

What optimization apps does Samsung have?

Android 11: Battery optimization, Auto-optimize, Adaptive battery, Adaptive power-saving, Background restrictions, lists of Sleeping apps, Unused apps, Deep sleeping apps, Never sleeping apps
Android Pie and higher: Device care, Background restrictions, lists of Sleeping apps, Unused apps, Auto-disable unused apps
Android Oreo and Nougat: App power monitor, Background restrictions
Android Marshmallow or below: Smart manager

Android 11
Android Pie and 10
Android Oreo and Nougat
Android Marshmallow and older

Android 11

On Android 11 Samsung will prevent apps work in background by default unless you exclude apps from battery optimizations. This is a severe divergence from standard Android process management policies.
Yes, this is a long way to go! Devs cannot ask for it automatically as they risk being kicked out from Play Store due to policy violations.

Lock the app in Recent

Open Recent apps.
Find Your app.
Long-press the icon of the app.

Battery optimization

To keep your apps working properly make sure you enable:
Settings -> Apps -> Your App -> Battery -> Battery optimization -> All apps -> Your app -> Don't optimize.

Optimize battery usage

Settings > Apps > (⁝) menu > Special Access > Optimize battery usage

Auto-optimize daily + Adaptive power saving

On some phones the route differs:

Adaptive battery

Lists of Sleeping apps, Unused apps, Deep sleeping apps, Never sleeping apps

Warning: Make sure Put unused apps to sleep is disabled. Otherwise, Samsung will put your apps back to sleep after a few days (3 by default) even if you have woken them up manually!

Android Pie and 10

Battery optimizations are turned on by default. It is possible the disabled restrictions might get revert after OS update or reboot. By default any app which is not started in 3 days is put to sleep and background tasks including alarms will stop working.

Put unused apps to sleep

Phone settings -> Device care -> Tap on the Battery item -> (⁝) 3-dot menu > Settings
Uncheck Your app from this list.

Auto-disable unused apps

Phone settings -> Device care -> Tap on the Battery item -> (⁝) 3-dot menu > Settings
Uncheck Your app from this list.

Background restrictions

Check that Phone settings -> Apps -> Sleep as Android -> Battery -> Background restriction state as App can use battery in background for the apps you need to run in the background.

Sleeping apps

Sleeping apps menu is the sniper's nest for Samsung's app killing policies. Make sure to follow the instructions very carefully to prevent the apps from being killed.

On some phones, the layout may differ:

Warning: Make sure Put unused apps to sleep and Auto-disable unused apps is disabled. Otherwise, Samsung will put your apps back to sleep after a few days (3 by default) even if you have woken them up manually!

Game Boosting features

Samsung optimizing features that monitor your phone usage and can alter your settings. Although such feature might be useful, in some cases you don't wish to loose all background processed. This can results in termination of background processes when you play games (for example blue light filter apps will stop, or notification are delayed).
There are Game Booster app, Game optimizing service, and Game Launcher.

Go to Apps and then click the Samsung app settings. Scroll to the Game Booster.
Turn off as much as you can. Then click Block During Game and shut off everything.
Next, in apps, find the game optimizing service - this cannot be disabled, but you can remove all permissions.
Last, search apps again and find the Game Launcher. You can remove the permissions and then disabled it.

Optimize battery usage

Battery optimizations are hidden under each app's settings section. To disable the optimization for the app, you need to expand the sub-menu, so the list reveals the apps, that are restricted. Open System settings -> Apps -> Your app -> Optimize battery usage, expand the list, and then set the app to "not optimized" with the toggle.

Android Oreo and Nougat 8 + 7

With the introduction of their flagship Galaxy S8 (and with some earlier experiments), Samsung has introduced an attempt at prolonging battery life called App power monitor.

App power monitor

App power monitor can be turned off completely, or you can manage the apps individually.
For your apps to work correctly in the background, you need to whitelist them in App power monitor and add them to Unmonitored apps:

Open the Settings -> Device maintenance -> Battery, and at the bottom you'll see a list of your most frequently used apps.
Apps that are sleeping will appear in the Sleeping apps list at the bottom (tap it to expand the list).
List of Unmonitored apps is at the very bottom (longer scrolling is needed) - these are apps that you specifically want to exclude (whitelist) from App power monitor evil reach.
When inside the Unmonitored apps menu, you can tap the 3-dot menu to add or delete apps from the list.

Android Marshmallow and below

On other Samsung phones, the path may look like this:

Phone settings > Applications > select three dot menu (top right corner) > Special Access > Optimize Battery usage > Find your app on the list and make sure that it is not selected.

Note: If you enable "Edge Lighting" for your app, the app will not be able to wake up your screen. To allow your app to wake up your screen, please remove it from the Edge Lighting applications list.

Solution for devs

No known solution on dev end

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