Why do apps (not widgets) consume power when running ?

[AC Question]

My S3 has been getting slower and slower. I installed a CPU monitor and it takes a two minute snapshot of CPOU usage and tells you what apps/widgets have uses power (it gives Average CPU use and MAX CPU use).

There are many apps that arent running that are using up CPU resources. I always though an app basically didnt do ANYTHING till it was launched,, unlike a widget that is kinda always running in background.

I would just uninstall these apps, but many i use.

What am i missing ?

Thanks

 

[Crashdamage]

Most services and processes (apps) are not actively running, they are just cached in memory. If an app is not active, it is not using a significant amount of power or CPU cycles. Let me explain a little more.

Besides being totally off, there are 3 basic states and app, or more precisely, a process can be in:

1. They may be inactive, literally doing nothing, just parked in memory for quick retrieval should they be needed again. As such they use no power and have no effect on the device's performance.

2. They may be service-only processes. Again, they are parked in memory for quick retrieval, but sort of have one eye open or an ear to the ground, listening for a command to get to work again. These normally use a very small amount of power. Not enough to be concerned about. The keyboard is a good example of a service process. Unless you are typing, the keyboard stays cached in memory, only very minimally awake, waiting for a tap on the screen to call it back to action. It stays active onlly while in use, then drops back to service status.

3. Then there's active processes. These are actually running and using CPU cycles and power. Usually they drop back to service staus or close down when not in use, but some do not, either by design or accident. Facebook is a notorious example of an app that leaves processes running, not only occupying RAM but using CPU cycles, power and generally slowing down the device and wasting battery. However, usually an app that stays active does so because it's necessary for it to do its job.

I hope that makes some sense and clarifies things a little.