Android Question Scheduled Services from killed app? [SOLVED]

W

W. Graf

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Good morning,

I have a problem with my app and I think, I have found the origin. But I'm not sure, if this is possible. Maybe you can help me?

My app contains a service, which is scheduled every 10-60 seconds. In most cases, everything is working fine. But rarely, my app crashes when service is starting at scheduled time. I think, that OS kills my app (because of low memory) before my service starts again at scheduled time.
For me, it looks like:
1.) I start my app
2.) Process-global variables are set and service is scheduled with StartServiceAt(...)
3.) OS kills my app (because of low Memory)
4.) My scheduled service starts, but my process-global variables are empty
Is this situation (step 4) possible? I'm testing on Android 4.3, 4.4, 6.0, 7.1.

By the way: do you have an idea, how can I simulate the situation, when Android kills my app from Memory? I want to test my app for this situations before I deliver it to the users? For example: if I go into the app-manager from Android (Settings - App Manager) and stop my app. Is this the same behaviour like Android do it, when memory is running out?

Thank you in advance!!

Best regards,
Wolfgang
 
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Erel

B4X founder
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W. Graf said:
My app contains a service, which is scheduled every 10-60 seconds.
Click to expand...
Newer devices will not let you start a service with such short interval if the process is not currently running. The limit is around 15 - 30 minutes.

W. Graf said:
But rarely, my app crashes when service is starting at scheduled time.
Click to expand...
You need to monitor the logs and find why it crashes.
 
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W

W. Graf

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Thank you for your response, but these were not my questions.

I think I know, why it crashes (I've already monitored and read many logs). Because of the logs, I have an assumption. To confirm my assumption, I need to know, if Step 4 (see my previous post) is possible...: Is it possible, that OS kills my app, but nevertheless my scheduled Service still starts?
 
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W

W. Graf

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Ok, I have found my answers...

About Question 1 (global variables are lost):
If you schedule a service to start at a specified time (StartServiceAt()) and the OS kills your app, then the scheduled service still starts at the specified time. But in this case, the app itself restarts (Starter.Service_Create(), Starter.Service_Start() will be executed), but the Main-Activity does not start. The global variables were lost and had to be set again (for example in Starter.Service_Create()).

About Question 2 (simulate the behaviour of Android, to kill an app):
Yes you can simulate it. You have to swipe out the app from the recent-app-list. If you do this, then a scheduled service will still start. But if you go in the Android App Manager (Settings - App Manager) and stop your app, then the whole process is completly ended and your scheduled service will NOT start. It seems, that swiping out an app from recent-app-list is between the states "totally stopped" and "running" ...

These are my findings from today. I hope, somebody will help it in future, but be aware of that I'm a beginner in Android-development. So maybe I'm wrong with my conclusions. I have no idea, why somebody has designed an OS with such unpredictable behaviour. Maybe I'm too old for todays OSes ... :-(

I wish you a great day!
 
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