Develop Reference

Why system time to time kill app which on foreground without exception?

I just try to understand the reason of it. Our app is really stable and optimized, but time to time it just switch off during the work on foreground mode. User is using it, and it' just closed without any crash or ANR messages - really bad experience. What we already did:
use UncaughtExceptionHandler and print logs to the disk for analyzing. Logs are empty, not information about crashes for these cases
used Firebase crashlityc - is empty too
checked app with help profiler and leakcanary - no leak, memory using ~200 Mb
A bit words about our app:
clear arhitecture, Kotlin, MVVM, coroutines, dagger, retrofit, room, one single activity app
app should work all time, infinitely. App is an interface for hardware terminal.
the most part of fragments are stored into the backstack and reused again, it help to make screen opening faster after first fragment using. No leak with it, no fragment or viewModels duplicates
we use glide for downloading and previewing user avatars. I'm afraid, that leaks could be a part of bitmaps or jpg. Profiler doesn't show it after 1-2 hours tests, but I didn't test it during for ex. one week
possible app interruptions happen more often, when device is uncharged or just started (first 10-20 minutes after device start)
the most part of clients has a bad WIFI connections
we have ~10 modules, the most part of them are own canvas libs
crashes happen in random moments...
we also have ANR problem for some clients, but we added ANR watchdog, so soon we will know the reason of it.
we have 50-60 singletons. I'm not sure, that is bad or good. The first plan was using much memory to make app faster.
For me it looks like a native crash or system kill, but how to repeat it? I still don't understand the real reason of it. If you faced with similar problem, please describe your experience, it could be helpful for us. Thx!

Memory keeps rising without getting memory leak notification from leakcanary

I am new to android Profiler and still a noob at memory management. At first, I am having a notifications from LeakCanary so I fix them and successfully removed the leakage so the LeakCanary stops sending me notifications. But when I use the android Profiler I just noticed that the memory usage was rising bit by bit when I open a certain activity and then destroy it using finish(); method. Below are the sample screenshots of my Profiler when I open and close the OrdersActivity.
Here is the SS of total memory used before opening and closing the OrdersActivity
And here is the SS of total memory used after opening and closing the OrdersActivity
Also here is the stacktrace of the LeakCanary
I want to know if this occurrence of rising memory is normal? If not, is there a way to stop this? I am willing to show my codes If you need them in order to help me. I just didn't include it because it was too long.

LeakCanary will detect memory leaks, in the sense of objects that remain in memory when the activity is closed.
If you want to understand why memory usage is increasing as an activity is running, you can track allocations using the profile.
Edit: Also, it's hard to read a screenshot, but it seems to me that was is increasing when you start the activity is code (Code: Memory that your app uses for code and resources, such as dex bytecode, optimized or compiled dex code, .so libraries, and fonts.). In that case, that's perfectly normal: starting an activity need to load extra code (the activity itself, which is probably small, and all of required AppCompat if it hasn't been loaded yet). The usual strategy to test against memory leaks is to start and close the activity hundred times, and verify there is no memory increase between the 2nd time and the 100th time.

android memory issue - app uses a lot of ram

I have some problems with the memory usage of my android app and don't know what causes the high memory usage. When I start my app, it uses up to 40 mb ram (says DDMS) and when I open another app, my app gets immediately killed.
I read a lot about memory leaks and I'm unbinding drawables, running the GC and so on but my app still needs a lot of memory.
I have about 3mb resources in my app, but afaik they are loaded into ram on demand. Am I wrong? May this cause the 40mb of ram usage?
EDIT: I think I'm not having memory leaks because I can switch the orientation on each activity as often as I want and the app does not crash because of low memory. So it can't be a memoryleak, can it?

you need to do memory management into your android application, please free the resources which is no longer used, try to override onStop(), onDestroy(), onPause() methods of Activity which will keep track of activity stack.
in OnDestroy() method free your whole availed resources, so that another app can use the same resources again.

What data structures are you using? Very large data structures (long Lists, big graphs, big maps, etc) can quickly use up RAM.
It could also be that you're leaking the Context on orientation change in your app.
It could also be that your layouts are really badly designed along with some heavy data structures.
It's difficult to tell unless you describe a bit more about what your app tries to do.

In my Android app, every other time I launch my app, it crashes with OutOfMemory Exception

I have an Android app that in the onCreate() method, preloads a lot of graphics.
When I test my app on my HTC Aria and launch it, it runs fine. However, if I press the back button to exit my app, and then launch the app again, it crashes with an OutOfMemoryError: bitmap size exceeds VM budget. If I then launch the app for the third time (right after it has crashed) it launches fine. Then if I close and re-launch it, it crashes again with out of memory. It continues this every-other-time-crashing pattern forever if I keep trying.
I checked to see what life cycle methods were being called and onStop() and onDestroy() are both being called when I exit the app, yet I have a feeling that something is not yet being cleaned up and that by "crashing" the app when I try to launch it the second time, it somehow free's the memory.
Any thoughts on what could be happening or how to remedy this? Please let me know if you need me to post more info. Thanks!
Info:
My app is fairly simple and only has 1 activity that plays some frame animations.

Maybe you are unnecessarily holding onto Context references? Check Avoiding memory leaks for some tips, as well as Attacking memory problems.

It sounds like something in the Activity life cycle is not quite right. Are you sure you have every start covered? http://developer.android.com/reference/android/app/Activity.html
You have onStop but do you have onDestroy? You're probably missing one of those that you need.

You may find some useful information the many answers to this question:
Strange out of memory issue while loading an image to a Bitmap object
Also, I second the "Avoiding Memory Leaks" blog post. Especially if you can trigger the same problem with orientation changes. Using "this" context when creating display objects is a sneaky way to leak the Activity context. In my own app, I managed to leak a whole chain of contexts, and would very rapidly run out of memory when doing orientation changes.

Stack memory in Android

I'm writing an app that has a foreground service, content provider, and a Activity front end that binds to the service and gets back a List of objects using AIDL. The service does work and updates a database.
If I leave the activity open for 4-8+ hours, and go to the "Running Services" section under settings on the phone (Nexus One) an unusually large amount of memory being used is shown (~42MB).
I figure there is a leak. When I check the heap memory i get Heap size:~18MB, ~2MB allocated, ~16MB free. Analyzing the hprof in Eclipse MAT seems fine, which leads me to theorize that memory is leaking on the stack. Is this even possible? If it is, what can I do to stop or investigate the leak? Is the reported memory usage on the "Running Services" section of android even correct (I assume it is)?
Another note: I have been unable to reproduce this issue when the UI is not up (with only the service running)

I'm writing an app that has a
foreground service, content provider,
and a Activity front end that binds to
the service and gets back a List of
objects using AIDL.
If that's all just one application, get rid of the AIDL and get rid of the content provider. Or, at least, don't use them yourself -- those are for other applications to use. They add overhead that you do not need for stuff inside your own VM.
...which leads me to theorize that memory is leaking on the stack. Is this even possible?
Not really. The main application thread stack is trivially small. Other threads have stacks that could get a lot bigger, but I'll be surprised if you are chewing up 42MB that way.
If it is, what can I do to stop or
investigate the leak?
Since you already did a "spike solution" of testing sans UI and determining that is OK, I'd slowly reintroduce the UI and see when you start getting the problem. One likely candidate problem area would be updating the activity from a background thread, so you might turn that off and see what happens.
Since your problem isn't in the heap itself, my guess is that your problem is tied to bitmaps or other things that have lots of off-heap RAM usage. The camera in your avatar is another hint in this direction. :-) Make sure you are recycle()-ing your bitmaps and such, and see if that helps any.