I have a service in my Android application that needs to continue listening for location updates after the user has exited the application (the implications of this on battery life are a separate matter).
I'm not sure that I have correctly understood the lifecycle of a service in Android, outlined on this page:
http://developer.android.com/reference/android/app/Service.html
I believe if it returns START_STICKY in the onStart() method then the service will continue to run after the main application has quit regardless of whether or not the service is running in its own process. If the service is running in the same process as the rest of the app and I have understood correctly, the main app's process is kept alive after the app exits, just to run that service. When the app starts again, it will run in the same process as the service, which is still running. If the system gets low on memory, Android may decide to kill this service.
Secondly, I believe it is OK to run the location listener listening for GPS updates in the same process and indeed same thread as the rest of the application and it will not block when waiting for updates from the GPS.
Have I understood correctly?
You have understood correctly.
If the system gets low on memory, Android may decide to kill this service.
If you want it to be persistent you can create persisitent service (but it needs to be a system app / service).
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.
For your location Listener:
Use the Location Listener implemented in a service.
Start listening the GPS when the service starts and remove the GPS listener when the service stops.
Start this service when you wants to listen to GPS(every 10 minutes for example).
This is cleaner than having a service you try to continuously run and checking for Location changes.
Secondly, I believe it is OK to run the location listener listening for GPS updates in the same process and indeed same thread as the rest of the application and it will not block when waiting for updates from the GPS.
You do not need to setup a AsyncTask or background thread for this. Also understood correctly.
The actual life cycle of Service is described here by image. You run whatever service in android the life cycle if always follow like this.
Related
I'm fighting with the Android desire of killing everything which isn't active on the screen. My problem in few words:
I have a microcontroller which communicates with a processor on which Android runs;
the processor must keep active a watchdog on the microcontroller, resetting periodically (every one second) one of its registers; an application, say App B, accomplishes this duty;
on the processor I can be sure about the persistent existence of another application, say App A (or, however, if App A dies App B can die too because the system is compromised) which for now does nothing, in the future will accomplish other duties.
Which is the best way to implement App B?
I tried the following solution: App B contains a Bound Service, say Service A, to which App A can bind on; Service A starts a thread, say Thread A, which periodically resets the microcontroller watchdog. Thread A is launched when app A sends a command to Service A (e.g. START_WATCHDOG).
In my idea, Service A lives until App A lives (thanks to the binding), and so the process to which Service A belongs lives, and so also Thread A.
Unfortunately, from tests I see that sometimes (in a sporadic manner), after some time (sporadic time, too), with almost no work running on the system (except for App A, Service A and Thread A) the system kills Service A process, and so Thread A stops and the watchdog elapses.
When Service A dies, it is restarted (because it is a Bound Service and App A is still running) but, for now, I don't save the current state of Service (which simply consists on the START_WATCHDOG command arrival or not) and this is the reason for which the watchdog elapses.
So, I've got several questions about my solution:
is it ok and I simply need to save the current state of Service A in order to restore it when restarted?
should I discover better the reasons for which Service A, or better its process, is killed?
is there a better solution for my problem?
Thank you very much to everyone who will spend some time to help me.
Being not sure about periods in which your service runs you can try these:
Use foreground service. However, you might need to acquire a wakelock within your service start point if you need cpu in long time. Plus, a notification needs to be shown on phone status bar.
Use WorkManager-new api part of jetpack simplifying the use of alarm managers and jobschedulers- to schedule your tasks periodically. However if your frequency is higher than 1 per 5-10minute then you will need to take care of doze mode. If phone gets into doze, your tasks might be delayed till maintenance periods. A trick to apply here might be starting a foreground service when you catch activation of doze mode and return back to Workmanager logic in deactivation(if you don't want user to see the foreground service's notification). Do whatever you want in the foreground service like.
Use Firebase Cloud Messaging to push notification from your server to your users periodically for you to have a small amount of time to do work in background. When notification comes, OS grants you an interval to run a task.
Use Work manager it is easy to implement.
I need to create a service that runs alongside the android app,irrespective of which screen of the app the user is on.
The app is a chat application so when the device is offline the service should queue up all the messages that are being sent offline and when the device is connected it should sync all messages.
I have written code for the job scheduler to sync data automatically when the device is online but while the app is active i would like to handle this manually.
Creating a Long Running service.
Operating system still can terminate the service in low memory and possibly other situations. There are 2 ways to overcome this:
If you are implementing the service, override onStartCommand() and return START_STICKY as the result. It will tell the system that even if it will want to kill your service due to low memory, it should re-create it as soon as memory will be back to normal.
AlarmManager .A system service, which will execute actions periodically. That will ensure that if your service will be terminated, or even the whole process will die(for example with force close) - it will be 100% restarted by AlarmManager.
Thank you.
You can do this by simple following steps:
Create Simple Service and after first launch of app just start at splash screen.
In Service after getting one data you can call another request.
After that you can create one broadcast action globally which will always call every network changed.
At background you can sync again data and saved it to shared preferences or as per your your requirement.
For interval you can also using AlarManager.
A part from this you can simply create Service using JobSheduler in this you can assign job and time as well.
Refer link :
https://developer.android.com/reference/android/app/job/JobScheduler.html
Hopefully this logic will helps you.
You have to use a intent service with sticky instead of service for this which will be executed in a queue and do your work. And since it is a intent service it will be started automatically after sometime, when system kills the service process.
I am working on an Android project and I need the app to work even when the device is locked.
The idea is to open the app that will start the (Intent)Service, the service processes the data all the time. The device can be locked/put away and after some time when the app is opened the service is manually stopped. The service should be running all the time in the background.
I have found information online, but I am not sure what to use and in which way..
I have found that the IntentService can be used. Also the service should run in a new thread. I need to process the data from gps all the time, should I use WakefulBroadcastReceiver?
Thank you.
IntentService is not necessarily what you want to use. It will automatically spawn a new thread just to handle an incoming Intent. Once all incoming Intents have been handled it will stop the Service. To have a long running Service, you would need to derive from Service and when it is started return START_STICKY from the onStartCommand() method, plus spawn your own thread to handle your background work.
If you need to monitor GPS, you'll have to manage that along with keeping the device awake using a WakeLock. Note that in Marshmallow, this gets more complicated because of the new Doze mode where even wakelocks are ignored.
Also, note that the way Android is architected there is still a chance that your application running the background Service may be killed. Android uses a unique process management technique based on memory pressure and user perceived priority to determine how long a process should stick around. I recommend reading up on the Service lifecycle in the documentation.
In android their is no fool proof way to ensure that your service runs forever because the LMK(low memory killer) when the system needs resources (based on a certain memory threshold) , kills the service then if it can restarts it. If you handle the restart properly the service will continue to run.
Services that are given foreground priority are significantly less likely to be killed off, so this might be your best bet. However their will be a notification of your service running the in the background on the menu bar up top. Foreground Service
I have started a service from my application and from that service a worker thread is started .I want my service to run even application goes background and until the user kills/exits the application.
But some cases my service got killed due to low memory ,then used sticky service or making the app to foreground to restart the service.
My issue is I dont want to lose the data between service ending and restarting time ,so is it possible to start another thread from service ondestroy method, but in this case how we can control that thread.
Please let me know is it the right approach ,and is this usecase achievable
I want my service to run even application goes background and until the user kills/exits the application.
This is not possible. The user can always get rid of your app, via Force Close in Settings, or via some device's version of the recent-tasks list.
But some cases my service got killed due to low memory
No, your process is terminated for low memory.
My issue is I dont want to lose the data between service ending and restarting time ,so is it possible to start another thread from service ondestroy method
No, because your process is being terminated.
Please let me know is it the right approach
Probably not. Very few apps need a service that runs constantly, which is why Android, and its users, go to great lengths to control such services. I would recommend that you try to find some solution to whatever your problem is that does not need a service running constantly.
I am making an android app which will have two services that will keep sending data about the usage of the phone by the user every 24 hours.
The user should execute the app, toggle the buttons to enable the logging of the usage of the phone and then the user should be able to do a normal life with his phone, until he starts again the app and disables the toggle button to stop the logging of the info.
What considerations should I take about the life cycle of the services?
What about the interaction of the user with the phone while the services should be sending the data?
All info is very much appreciated, as I my mind is getting a little bit overwhelmed with all this!
Thanks a lot in advance everybody!
The service can be cut at any time through the settings menu. It can also be killed at any time by Android if it decides it needs the resources for the currently running activity. onDestroy() will be called regardless so use that to store anything needed.
The service runs in the background but through the main UI thread. Thus, it is possible to block operation of the phone through a service. It looks like the phone locked up when it's really a service trying to do something. Any blocking procedure should be used in a thread such as Java timer, Java thread, or AsyncTask.
There can only be one running version of the service at any given time. However, calling startService(myService) if "myService" is already running will essentially override the current running service and onStartCommand() will be called again. However, one call to stopService(myService) is needed to stop it no matter how many times startService(myService) was called.
stopService(myService) will not stop a service if the service is bound to anything. It will wait until all bindings are removed before the service stops.