WorkManager backoff delay doesn't work on some devices

Question

I want to start a Worker that performs some task, and in case of error tries again after some delay with exponential backoff strategy.

Here is simplified Worker for the sake of brevity:

class TestWorker(
    context: Context,
    workerParameters: WorkerParameters
) : Worker(
    context,
    workerParameters
) {
    override fun doWork(): Result {
        Log.d("DEBUG", "Attempt $runAttemptCount")
        return Result.retry()
    }
}

And this is how I schedule this Worker:

class MainActivity : AppCompatActivity() {

private val TAG = "WORKER_TAG"
private val BACKOFF_DELAY_SECONDS = 60L

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val workManager = WorkManager.getInstance()
        workManager.cancelAllWork()
        val workRequest = OneTimeWorkRequest.Builder(TestWorker::class.java)
            .setConstraints(
                Constraints
                    .Builder()
                    .setRequiredNetworkType(NetworkType.CONNECTED)
                    .build()
            )
            .setBackoffCriteria(
                BackoffPolicy.EXPONENTIAL,
                BACKOFF_DELAY_SECONDS,
                TimeUnit.SECONDS
            )
            .addTag(TAG)
            .build()

        workManager.enqueue(workRequest)
    }
}

It works great on the majority of the devices, however I observe weird behaviour on some devices.

I expect Attempt 2 to be executed after 1 minute, but on Samsung J1, 6.0.1 I see the following log:

01-15 12:39:57.438 28396-28435/test.ru.workerissue D/DEBUG: Attempt 0
01-15 12:39:58.349 28396-28439/test.ru.workerissue D/DEBUG: Attempt 1
01-15 12:39:58.389 28396-28440/test.ru.workerissue D/DEBUG: Attempt 2
01-15 12:40:59.669 28396-28435/test.ru.workerissue D/DEBUG: Attempt 3
01-15 12:40:59.719 28396-28439/test.ru.workerissue D/DEBUG: Attempt 4

As you can see, the delay between all attempts except 2 and 3 is about 1 second.

If I run the same code on Nexus 6X, 8.1, I observe two attempts fired on startup simultaniously, and then everyting works as expected:

2019-01-15 13:01:06.610 28806-28841/test.ru.workerissue D/DEBUG: Attempt 0
2019-01-15 13:01:06.658 28806-28842/test.ru.workerissue D/DEBUG: Attempt 1
2019-01-15 13:02:06.747 28806-28975/test.ru.workerissue D/DEBUG: Attempt 2
2019-01-15 13:04:06.876 28806-29024/test.ru.workerissue D/DEBUG: Attempt 3

Also, I tested this on several other devices: Samsung Galaxy J3 - 8.0, Google Pixel XL - 8.1, Samsung Galaxy J1 - 5.1.1. Works as expected on all of these devices.

The version of WorkManager is 1.0.0-beta01

What could be the reason of such inconsistency? Is it possible to fix it?

Answer 1

I created the issue and it should be fixed in the next release of WorkManager: https://issuetracker.google.com/issues/122881597