Android P introduces amazing tool called App Standby Buckets, which is a power saving app. The app is based on how frequently you use them and limit their access to device resources.
The system will not restrict the apps that you use most whereas apps that you never use will have strict restrictions imposed on them. The system assigns each app to a priority bucket. This brand new feature essentially limits apps’ access to device resources like the CPU or battery based on the user’s usage patterns.
The system does not impose any restrictions, when app placed in the active bucket. An app that is open or running a foreground service is categorized as “active.”
An app that is placed in the working set bucket is subject to mild system restrictions. An app that runs often but is currently inactive will be come under this. These apps may not be able to run jobs or trigger alarms.
If an app is used regularly but not daily, the app will be in the frequent bucket. The system also imposes a cap on high-priority FCM messages.
If an app is not used often, it is placed in the rare bucket. The system also places a limit on its ability to connect to the Internet. The never bucket is for apps that have been installed but have never been run. They are subject to severe restrictions.