AlarmManager occasionally doesn't fire alarm

Question

I'm developing a live wallpaper for Android. To refresh the wallpaper at set times I use AlarmManager. Most of the times this works great, but occasionally my alarm isn't received. On top of that I can't replicate this behaviour, it just randomly happens. I've run into this using at least 3 ROMs.

Now for the code.
I use this PendingIntent:

mRefreshIntent = new Intent()
    .setComponent(new ComponentName(mContext, RefreshBroadcastReceiver.class))
    .setAction("my.package.name.REFRESH_WALLPAPER");
mPendingRefreshIntent = PendingIntent.getBroadcast(
    mContext, 
    0, 
    mRefreshIntent, 
    PendingIntent.FLAG_CANCEL_CURRENT);

This is my code to set the alarm:

mAlarmManager.set(AlarmManager.RTC_WAKEUP, time, mPendingRefreshIntent);

where time is the UTC time in milliseconds. I often verified if the alarm is set as intended using adb shell dumpsys alarm, which it is.

The receiving side:

public class RefreshBroadcastReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Log.d("DayNight", "onReceive     ; " + System.currentTimeMillis());
        DayNightService.refresher.refresh();
        Log.d("DayNight", "onReceive done; " + System.currentTimeMillis());
    }
}

Associated manifest lines:

<application>
    ...
    <receiver
        android:name="RefreshBroadcastReceiver">
        <intent-filter>
            <action android:name="my.package.name.REFRESH_WALLPAPER" />
        </intent-filter>
    </receiver>
    ...
</application>

Alarms which are not fired always exist in the queue (dumpsys alarms) beforehand, and are not in the alarm log afterwards. Seems like they get 'lost' at T minus zero.

I will be very happy if one of you can solve this problem for me.

The same thing is happening to me if I cancel an existing alarm and recreate it with a new time. It shows on the adb with the correct time remaining but once it hits 0 nothing happens. — draksia, Oct 10 '12 at 20:02
I suppose this is a bug in AlarmManager. I have a similar problem where an Alarm that was scheduled a long time ago was somehow forgotten. This is also happening if i catch the boot complete intent and reschedule after reboot. — foobar, Feb 28 '13 at 19:38

score 2 · Answer 1 · answered Dec 09 '11 at 15:11

I use following code:

  Intent intent = new Intent(ACTION);
    PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_NO_CREATE);
    Log.d(LOG_TAG, "pending intent: " + pendingIntent);
    // if no intent there, schedule it ASAP
    if (pendingIntent == null) {
        pendingIntent = PendingIntent.getBroadcast(context, 0, intent, 0);
        // schedule new alarm in 15 minutes
        alarmService.setInexactRepeating(AlarmManager.RTC, System.currentTimeMillis(),300000, pendingIntent);
        Log.d(LOG_TAG, "scheduled intent: " + pendingIntent);
    }

Note, that I request inexact repeating alarm and RTC ( not RTC_WAKEUP ) - if phone is sleeping deep inside jeans pocket, user is not interested on changes of your live wallpaper - no need to waste battery juice and wake phone up

You may also need to register boot complete broadcast receiver to start update scheduling on reboot.

This is not really what I'm looking for: the refresh intervals are different each time and I'm not (yet) concerned about battery life (I could replace RTC_WAKEUP with RTC if I were). Maybe you could point out where exactly there is an error in my code or a bug in AlarmManager? — Thomas, Dec 09 '11 at 15:27
The first one in `WallpaperService.WallpeperEngine.onCreate()`. The next alarm is set when the previous is triggered, and so on. — Thomas, Dec 09 '11 at 15:55

AlarmManager occasionally doesn't fire alarm

1 Answers1