Work Manager not working when app is killed by the user. Why?

As I found out, the work manager depends on the device manufacturer. In my case, it is an miui device, which does not allow work manager to work in case the app is killed or rebooted. The work manager worked when I provided the application with "autostart permission".

Work manager completely depends upon the manufacturer, Some manufacturers or you can also say devices with stock ROM were allowing work manager to work as it should be, but there are some devices manufacturers ("Chinese ROM's") were very aggressive while clearing the background apps, they're even killing the work manager, however, Google is trying to make work manager work normally on all devices by talking with OEM's.

As of now If you really want to run anything in the background, you can turn on autostart option in xiaomi & some other devices or else you can also show a notification in notification tray which makes an app to run in the foreground. you can check whether the app is still running in the background or not, if not you can restart it.

if (!isServiceRunning(this, MyService::class.java)) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            startForegroundService(Intent(this, MyService::class.java))
        } else {
            startService(Intent(this, MyService::class.java))
        }

    }


 private fun isServiceRunning(context: Context, serviceClass: Class<*>): Boolean {
    val activityManager = context.getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
    val services = activityManager.getRunningServices(Integer.MAX_VALUE)

    if (services != null) {
        for (i in services.indices) {
            if (serviceClass.name == services[i].service.className && services[i].pid != 0) {
                return true
            }
        }
    }
    return false
}


 val am = getSystemService(Context.ALARM_SERVICE) as AlarmManager
    val pi = PendingIntent.getBroadcast(
        applicationContext,
        34,
        Intent(this, MyBroadcastReceiver::class.java),
        PendingIntent.FLAG_UPDATE_CURRENT
    )
    am.setExact(AlarmManager.RTC_WAKEUP, System.currentTimeMillis() + 10000, pi)

And Finally in Broadcast receiver.

 override fun onReceive(context: Context?, intent: Intent?) {
    Handler(Looper.getMainLooper()).post {
        if (!isServiceRunning(context!!, MyService::class.java)) {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                context.startForegroundService(Intent(context, MyService::class.java))
            } else {
                context.startService(Intent(context, MyService::class.java))
            }
        }
        val am = context.getSystemService(Context.ALARM_SERVICE) as AlarmManager
        val pi = PendingIntent.getBroadcast(
            context, 34, Intent(context, MyBroadcastReceiver::class.java),
            PendingIntent.FLAG_UPDATE_CURRENT
        )
        am.setExact(AlarmManager.RTC_WAKEUP, System.currentTimeMillis() + 5000, pi)
    }
}