Inquiry related to AlarmManager and WakeLocks

Question

I am developing a native android app that run a backup operation every 30 mins.

I am using AlarmManager for this purpose and it works fine. Here is the code I am using to start the alarm:

public static void startSync(Context context) {
        alarmIntent = new Intent(context, AlarmReceiver.class);
        pendingIntent = PendingIntent.getBroadcast(context, 0, alarmIntent, 0);
        manager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
       // int interval = 3600000;
        int interval =30000 ;
        manager.setInexactRepeating(AlarmManager.RTC_WAKEUP, System.currentTimeMillis(), interval, pendingIntent);

        ComponentName receiver = new ComponentName(context, SampleBootReceiver.class);
        PackageManager pm = context.getPackageManager();

        pm.setComponentEnabledSetting(receiver,
                PackageManager.COMPONENT_ENABLED_STATE_ENABLED,
                PackageManager.DONT_KILL_APP);
        Toast.makeText(context, "Sync Started", Toast.LENGTH_SHORT).show();
    }

And here is the the on receive method:

public class AlarmReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent arg1) {
        PowerManager pm = (PowerManager) context.getSystemService(context.POWER_SERVICE);
        PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "My Tag");
        wl.acquire();
        Intent eventService = new Intent(context, SyncInBackground.class);
        context.startService(eventService);
        wl.release();
    }
}

I noticed that when my device isn't in standby, the operation took 5 seconds (I calculated it programmatically) but when the mobile is in standby mode it took 11 seconds. That's why I used wake_lock before running the backup operation in a background service, in order to make the app takes only 5 seconds.

But I still get the same results if the mobile in standby mode... it still takes 11 seconds and 5 seconds if not in standby mode.

What can I do to make my background service run the repeating alarm in 5 seconds instead of 11 seconds?

Answer 1

The usual mistake: acquiring a wake lock in the OnReceive does nothing. The AlarmManager already holds a wake lock in OnReceive. Your way works out of pure luck, when/if it works. You have to either use a WakefulBroadcastReceiver or use a WakefulIntentService. The WIS will acquire a static wake lock which will be active between OnReceive returning and the service starting.

See my answer here: Wake Lock not working properly for links.