Firebase Job Dispatcher

Question

I'm creating an application which needs to send a request to an API. This request has to be send every 2 minutes. To do this I'm using Firebase Job Dispatcher

The problem is that the first request is send at time but the next ones are sent with a greater delay: eg.

first request: sent after 2 minutes
second request: sent after 2.3 minutes (instead of two)
third request: sent after 3.5 minutes (instead of two)
fourth request: sent after 5 minutes (instead of two)

As you can imagine, after a day, the delay will be 30 minutes or even more...

here is the code I used to create the job (in main activity - onCreate)

        Job pingJob = mDispatcher.newJobBuilder()
            .setService(PingJob.class) // the job class to execute
            .setTag(PingJob.TAG) //tag - name of the job
            .setRecurring(true) // repeat
            .setTrigger(Trigger.executionWindow(60, 60*2))
            .setReplaceCurrent(false)
            .build();

    mDispatcher.mustSchedule(pingJob);

Here is the PingJob class (to be sure the issue wasn't what i was doing in onStartJob, I only put a log):

public class PingJob extends Job {
    public static final String TAG = "ping_job";

    @Override
    public boolean onStartJob(final JobParameters params) {
        Log.d("ping job", "just put a log to see when is executed");
        jobFinished(params, true);
        return true;
    }

    @Override
    public boolean onStopJob(JobParameters params) {
        return false;
    }

}

I'm using an Android box with Android 6.0.1 (but my application has to run on 4.3 device too that why I'm using firebase instead of JobScheduler) and Google Play services 11.5.09 (434).

Do you have any ideas why it's doing this ? and if there is a way to get around this problem ? if not, is there a other way to do a job every 2 minutes ?

score 1 · Accepted Answer · answered Oct 03 '17 at 08:54

1

You're doing nothing wrong. This is a designed expected behaviour. FirebaseJobDispatcher uses a scheduling engine inside Google Play Services which likely to use JobScheduler under the hood for Android 5.0 and higher. JobScheduler batches tasks from different apps into one batch to not wake up a device too often and save a battery. So there's no guarantee that your task will be executed exactly every 2 minutes. If you need this precision consider using AlarmManager which is not recommended for doing any network calls as it affects a battery life.

Why do you even need to send a request such often? Consider to think more about what you're doing. It might be better to save the data you're sending to the backend in a database or on a disk. Then you can send it in batches every 30-60 minutes or whatever works for you. You can also use Firebase Cloud Messaging to send a message to a device to ask it to send the data to the backend when it's needed.

answered Oct 03 '17 at 08:54

andrei_zaitcev

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First thanks for you answer. it's a digital signage app so I need to send this request every two minutes because we need to know if the app is still running/connected to ease the support when our clients are calling us. – dev Oct 03 '17 at 09:09
Try AlarmManager and IntentService then. Not perfect, but should work fine for your case if you don't care a lot about battery. – andrei_zaitcev Oct 03 '17 at 09:20
Ok i'll try, the battery isn't a problem, it is a box which is always plugged on electric power. Thanks a lot – dev Oct 03 '17 at 09:46
How can I mark your comment as the solution ? Or is it a better idea to mark your answer as the solution ? – dev Oct 04 '17 at 10:18
@dev my answer already contains information about AlarmManager. So if it works for you then I think that the answer itself should be marked as a solution. – andrei_zaitcev Oct 04 '17 at 10:20

Firebase Job Dispatcher

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