Android are a multi-tasking phone. If you used the app it still runs -- why, Google will have to answer that. However, try using the aggressive setting in ATK and see if that helps. It seems to work for me. I'm down to about 4 apps running, rather than the dozen that used to run.
i just ignore them. i don't use an app killer. they seem to have no (or VERY little) affect on the performance of my phone. i had a task killer for months, but then uninstalled it after the 2.2 update. i haven't noticed any difference in performance if i just let them all run.
This subject has been talked about a lot in here since the Droids release. I've talked to a developer who is very well versed in Linux/Android and he summarized the following as correct......
Android is different to most other phone operating systems. It's closer to Linux than any other type of operating system. Lots of services and applications constantly run in the background just like they do on Windows. However, and this is important, they do not have to use up a ton of resources. A service or app can be loaded, yet use almost no additional memory, and 0% CPU until it actually has to do something.
In general, killing off stuff is a waste of time. Android automatically asks apps to close that aren't needed when it needs more memory. Killing off some of the processes you are killing off also means it'll slow your phone down, as these processes only need to reload, and when you do need to use them it means the phone will be slower for the few seconds it takes to reload them.
Next post: Android isn't "close" to linux, it IS linux.. that is the OS that runs on all android phones is a linux kernel, 2.6.x. Android is a platform that runs on top of the linux kernel and handles the task of starting up individual Dalvik JVMs for each app you run. Each and every app you see running in your task list is a separate JVM instance all to itself, so that if the app crashes the JVM, it ONLY brings down that one app. The phone still works, as do the other apps. Each time you install an app, it's installed as a separate user as well. So each app you run, runs as it's own separate user too, making it that much more secure from one app to the next.
Here is the thing to know tho.. Android is in control. Period. Android WILL KILL AN APPLICATION FOR YOU! In other words, if you start running out of memory, Android will send some signals to the app saying "Yo.. I really really need to use some of those resources you got tied up.. so I am shutting you down, completely. Here's your last chance to save any state..." and boom! Gone. Android thus will indeed handle memory as needed on the fly for you. Now.. what happens when you switch back to that app you left running but Android shut down? Well, it starts up again. If the app was built correctly, it will receive a bundle of info pertaining to state info that it should have saved when Android killed it. If done right, it will resume as if nothing happened. You will see a slightly longer delay than if it was still running, as it is now starting up a JVM again to run the app in, and the app may have to reload some state, screens, tiles, graphics, sounds, etc.
Please tell me how killing UNEEDED items is a waste...lol
It is indeed a waste. I am telling you now as a developer, albeit a new one, but one who has been doing java for over a decade and understands the basics of how all this works. Android WILL shut down apps (as I explained above in detail) when it needs to in order to reclaim resources so that the top app (foreground) might have resources to do something with. Even if the foreground app doesn't need them, Android will kill apps if need be as necessary. As I said above, even tho it actually shuts the app down, it goes thru steps to allow an app to cleanly shut down AND recover from the shutdown as if it was never shut down. The app developer just has to write the code correctly to handle this situation.
So, essentially, killing apps becuase you are afraid you are running out of memory is not needed. There is ONE possibility tho.. an app could run out of memory itself! It could load a very large dataset into memory and not have enough. I haven't found/read anything about how Android itself handles swapping memory to disk.. as I don't think you can set up swap memory to the SD card. It would be VERY nice if you could do this, it would allow more robust apps to at least use more memory than 128MB or 256MB the phone comes with. It would also see minor bumps in performance when it was time to swap some memory to the SD card to free up memory, or bring it back in. Windows, Linux, OSX, they all do this for you. I suspect the underlying linux OS handles this, but not quite sure if it does so or not.
ATK shows apps running in the background. Actually, they are not. Click settings, about phone at bottom, battery, battery use and it will show you what is actually running.
Amazingly, it was a verizon rep who told me to d/l atk. I have deleted it. Those apps are not running.
Let me summerize the prior lengthy post.
Task killers can actually hurt your phone by closing things your phone needs and/or closing an app that will just restart anyway, which actually uses some of your CPU which is NOT being used when they are "running"
If you want better battery life, pay attention to apps that eat battery. Either tweak settings so they arent running as much or find an alternative which uses less battery.
Remember, always plug in your phone when you can. Lithium batteries dont need to be discharged, in fact discharging too much CAN harm the battery in the long run.