Android process produces logcat "has died" message very often.

Question

I am working on an app that runs as a service and waits for a message. After I check the log, I find out that Android kills and restarts many processes very often! This not only happens to my app, but is the same for many other services.

I cannot see any reason for this and my device has enough memory. I test with a Sony Xperia S running Android 4.0.4. Is this normal or a bug?

Here is a part of the log to show you what I mean:

02-04 15:02:38.791 320 332 I ActivityManager: Process com.android.email (pid 32763) has died. 02-04 15:02:38.791 320 332 W ActivityManager: Scheduling restart of crashed service com.android.email/.service.MailService in 5000ms

.... and 13 minutes later :

02-04 15:15:32.601 320 694 I ActivityManager: Process com.android.email (pid 1453) has died.

Answer 1

It's normal, the OS does this regulary.

Why? Every App or Service when inactive or in the background remains in memory until Android memory manager decides it is either taking up too much memory for nothing, or when another active app/service needs it. For example when you hit the home button when you are in your e-mail app. It will return to the exact place where you were when re-opening the app. Because this app was simply paused and in some sort of hibernation mode in the memory. Unless Android needs to allocate that memory for anything else, it keeps it there.

A way to make sure the OS does not kill your service, is creating a persistant service.

You can only make your service persistent if you are developing system apps. These services will be basically un-killable, and are labeled as "PERS" in the output of the "adb shell dumpsys activity" command.

http://www.androidguys.com/2009/09/09/diamonds-are-forever-services-are-not/

But:

Please use AlarmManager and an IntentService, so your service does not need to be in memory except when it is doing meaningful work. This also means Android is rather unlikely to kill your service while you are in memory, and users are unlikely to kill your service because they think you are wasting memory.