Service is not waking up device as it should

问题

My application do a repeating request each second - asking the server for a new data, and if there is such - it wakes up the device and run the main application. ( this is by the request from the users, and they does not care about the battery usage, it is mandatory to run each second. It is Highly Critical Operation ) ( any changes to the settings which could help is allowed by the user )

I am curently trying to achieve this by using either AlarmManager or System.Threading.Timer ( tried with both ), but each time I am ending up with the follow issue :

• The device stop requesting the server at some point while it is slept and at some look-like random time it restore it's work for a short. Why this happens, and how to fix this issue ?

( OS : Android 5.x )

The code from the variation of the service in Java ( using AlarmManager )

Calendar cal = Calendar.getInstance();
        cal.add( Calendar.SECOND, ConfigReader.serviceRepeatInterval );

        Intent intent = new Intent( this, SaleService.class );

        PendingIntent pintent = PendingIntent.getService( this, 0, intent, 0 );

        AlarmManager alarm = ( AlarmManager )getSystemService( Context.ALARM_SERVICE );

        alarm.setRepeating( AlarmManager.RTC_WAKEUP, cal.getTimeInMillis(), ConfigReader.serviceRepeatInterval, pintent );

The code from the variation of the service is C# ( Xamarin ) using Timer.

public override StartCommandResult OnStartCommand(Intent intent, StartCommandFlags flags, int startId)
        {

            if( _powerManager == null )
            {
                 _powerManager = (PowerManager)this.GetSystemService(PowerService);
                _wakeLock      = _powerManager.NewWakeLock( WakeLockFlags.Full | WakeLockFlags.AcquireCausesWakeup | WakeLockFlags.OnAfterRelease, mySaleServiceWakeLock );
                 vibrator      = (Vibrator)this.GetSystemService( Context.VibratorService );                
            }

            timer = new System.Threading.Timer( getCurrentPendingObjects, null, timerRepeatInterval, Timeout.Infinite );

            return StartCommandResult.Sticky;
        }

回答1:

Using AlarmManager.ELAPSED_REALTIME_WAKEUP or AlarmManager.RTC_WAKEUP will wake the device up when the alarm fires.

The device stop requesting the server at some point while it is slept and at some look-like random time it restore it's work for a short. Why this happens, and how to fix this issue?

This might happen because your PendingIntent is calling a Service. This way the device can go back to sleep before onStartCommand() gets executed. You should use a BroadcastReceiver instead (since a WakeLock is "guaranteed" during onReceive()), aquire a WakeLock in onReceive(), start your Service from there and release your WakeLock from the Service, when appropriate.

Although, repeating a request every second for an extended period of time (and even when the device is in sleep) seems like a terrible design. It will drain the battery pretty fast.

You should rethink your implementation, maybe use some sort of a callback mechanism instead, or at least increase the intervals between the requests (significantly).

来源：https://stackoverflow.com/questions/37811079/service-is-not-waking-up-device-as-it-should