does location manager keeps working when device goes to sleep?

Question

My application requests for updates in a service on background when a boolean flag is set to true. If flag is set to true, then i acquire a PARTIAL_WAKE_LOCK to let my background service run. My questions are:

• Since I requested for updates from location manager ( i don't manually request updates but subscribed for locationManager.requestLocationUpdates )... does the locationManager keep working as normal/usual even if device goes to sleep with PARTIAL_WAKE_LOCK ?

• I've read there is a WifiLock -> WIFI_MODE_SCAN_ONLY that I'm not acquiring. Since location manager uses wifi scans to detect location through wifi hotspots, should I acquire this as well ?

• What about gps location updates when device goes to sleep ?

Answer 1

1. no, it does not. More (very good) info here, including possible solutions/ hacks.

2. regarding 1, I would have to make an educated guess and say it wouldn't make a difference

3. from what I can gather, it doesn't make a difference which provider you are using for the updates, LocationManager.NETWORK_PROVIDER or LocationManager.GPS_PROVIDER.

in danger of going a bit OQ, I am a bit curious which kind of application would need to aquire a wake lock to keep a service running at all. As far as I know, having a wake lock doesn't ensure your Service keeps running. The only thing which ensures a Service keeps running is to have it in the foreground (Service.startForeground()). Otherwise the system still might kill the service, regardless if it aquired a wake lock or not. That being said, if it is running, it can do it's work with a Handler or something.

If you are using this approach, and I think you are based on the scenario, I would advise against it. Basically you are creating a service, have it run in the foreground (guess) AND you are aquiring a wake lock just to request for location updates when the screen is off. This seems a bit overkill.

There's a more efficient way, which has the benefit it has by far more accurate timing then the dreaded timing of Handler.postAtTime or Handler.postDelayed: AlarmManager.setRepeating(). Set type to ELAPSED_REALTIME_WAKEUP or RTC_WAKEUP so it will run if the device sleeps, then when the alarm event is fired and received by a BroadcastReceiver you will have to create, you could request for updates and handle other events.

If you're not using a Handler, but are merely requesting location updates, this approach still probably would be better, because it doesn't require you to have a running Service or to acquire a wake lock.

And it seems LocationManager.addProximityAlert() is the way to go here. Which is flawed as well (see 1)

Similar question here by the way: Android: GPS location updates when the cellphone is in sleep?