I start some parallel tasks from a PCL with
Parallel.Invoke(() => ExecuteTaskAAsync(), () => ExecuteTaskBAsync());
Now I want to know on which thread these tasks are running.
Thread.CurrentThread.ManagedThreadId seems to be only available in the iOS
and Droid project but not in the PCL or UWP project. What are my possibilities? If I would use DependencyService I also won't know on which thread TaskA is running, because there is not relationship between the started task and DependencyService.
How can I get thread information (id, name, ...) in a PCL?
When you set a breakpoint you can get into the Tasks Window and get some more information. Also you have a drop down on the top to select a process, choose between different threads and get some info about the stack frame. So one should be able to also get this information in code?
Edit:
Seems that the informations in the Tasks Window is only available when running on UWP.
The concept of threads is completely absent in Windows Universal Apps and the use of tasks is recommended instead of threads.
I haven't found official documentation on the reasons behind it, but there's an ongoing discussion at the CoreFX's github repo.
So it looks like what you are looking for isn't currently possible if you want to support UWP projects.
You mal alternatively look for the TaskScheduler that manages the currently running task:
var poolId = TaskScheduler.Current.Id;
This way you can at least find out, if your method is running on the same ThreadPool (eg: They are executed on any background threads, or the UI thread).
As far as I know, to find the TaskScheduler for the UI, you have to call TaskScheduler.Current.Id while you are on the UI Thread and just store it in a variable.
This works for me
Environment.CurrentManagedThreadId
Related
I just started learning UWP and i'm really confused on how it works. I already saw tens of posts that talk about my problem but can't figure out how to do what I want.
So I want to make an app that runs on windows startup, I want the app to be not visible so it needs a background Task, how can I trigger this background task without getting to the app UI ?
The app is supposed to have the Background Task always running, and its interface is supposed to be used as "settings" so I don't need the app to be shown on startup.
Thanks.
I found my way here after a lot of googling. to be honest I have come to the same conclusion as Motaz. But as of writing this I am way too invested in what I have already. While what I have here is not the perfect answer to his question. I wanted to come back and post what I've learned for anyone else who ends up here.
My need is a app that when started will monitor a third party USB device until the app is closed (regardless of whether the app is minimized or not)
Windows Template Studio is good, but the docs not so much. Especially when it comes to Background tasks.
I started here: https://github.com/Microsoft/Windows-universal-samples. But there is two problems.
They combined all the examples and some of the code is shared, which makes it difficult to pull a project out and hack it apart without breaking the original examples.
Following their background task example I perpetually had issue with the manifest and and it wanting an audio task
I went back to the template studio and created the simplest version with a background task possible. After a lot of trial and error I got something that works. I have posted it here: https://github.com/PillarOfSociety/WindowsTemplateStudio-BackgroundTask
Some things to note:
I am no expert on UWP and while this runs I have no intent on putting it in the store nor did I try.
If you do download my project and run it, you should be able to just hit the "Add events" and the "Start Back" button and the task should run and update the Progress bar.
I used an ApplicationTrigger. the original example from the template uses a TimeTrigger which takes time in MINUTES (took me too long to figure that out). Supposedly Application triggers have a 30sec timeout.. but on my laptop they live for much longer.. I don't know how long. This page is useful: https://learn.microsoft.com/en-us/windows/uwp/launch-resume/support-your-app-with-background-tasks
The template studio generated BackgroundTaskService will leave background tasks registered after the app is closed, but will NOT make the connection back to them once its rerun, so on a rerun either the task appears not to run, or will crash the app when triggered.
Important Code I discovered:
foreach (var task in BackgroundTaskRegistration.AllTasks)
{
TestText += task.Value.Name; //gets the typename of the task
//task.Value.Unregister(true); //will unregister tasks
}
await Task.CompletedTask;
The tasks in BackgroundTaskRegistration.AllTasks are not the BackgroundTask class that the template studio uses. IN my example I unregister all of them each time it runs so that you have a reference to the task as an instance of BackgroundTask.
Hopefully this helps someone and Good luck!
If you're just starting out use Windows Template Studio, it will be perfect for you. It is an extension of Visual Studio which lets you create new uwp projects with a lot of built in features, and you can only choose the features you want. It will save you a lot of time on basic stuff.
https://github.com/Microsoft/WindowsTemplateStudio
I'm new to the UWP, and I'm facing right now an issue where I want to continue an operation that the app was doing before getting into suspended or terminated state.
I've read about Extended execution and background task, but as far as I have understood for extended execution you have only 30 seconds before it gets terminated or it could be revoked before getting into it.
for Background task I should make another project for it ( Windows Runtime Component) and I have to add an entry in the Declarations in the appxmanifest. It sounds that Background task is the only possible way to achieve it, but how to move an operation (Action, Func, or task or whatever) to background task if the app get into those states and what should happen after resume?!
Any ideas from experienced people?
Windows 10 universal Windows platform (UWP) app lifecycle
Before Windows 8, apps had a simple lifecycle. Win32 and .NET apps are either running or not running. Now, there are three app model in UWP app Running in foreground,Running in background and suspended state. You could know more detail through this official document.
Extended execution
There are cases where an app may need to keep running, rather than be suspended, while it is minimized. If an app needs to keep running, either the OS can keep it running, or it can request to keep running.
For this scenario, you need use ExtendedExecution to realize. ExtendedExecution support to start a long running operation in order to defer the Suspending state. And there are some document and code sample introducing this feature.
Background Task
For Background Task, it provide functionality when your app is suspended or not running. You can also use background tasks for real-time communication apps like VOIP, mail, and IM. However, it will trigger under specific conditions. For more please refer this.
You have mentioned out-process Background Task in your case and another Background Task(in process) could also be used in UWP app. It is simpler to implement than out-of-process background tasks.
Hi, I've tried to create a Thread in windows phone 8.1 without success.
Althought in msdn documentation is written that Thread is supported, actually do not works (https://msdn.microsoft.com/en-us/library/274eh01d(v=vs.110).aspx)
so I can't figureout how can I create a Thread, I want to create a Syncronization context to execute async on a single thread (not current thread), but just to achieve what event loop do
thanks
update for further information:
I would be more specific:
platform is universal app, so I mean windows 8.1 & windows phone 8.1, no silverlight ecc.
I need to create a thread because I want to create a syncronization context to execute some async code, here is an example about what I mean http://blogs.msdn.com/b/pfxteam/archive/2012/01/20/10259049.aspx
the difference from this link is I would use a specific thread for all async code instead current thread.
thanks again
If you just want to run some code asynchronously, look into using Task.Run. It provides a much simpler mechanism than managing threads yourself.
If you are building an Universal Windows Phone 8.1 app, you can't use the .NET Thread type. If you need more control over the execution, you can use the WinRT ThreadPool.
Finally, if you really really need lots of control, there's always CreateThread if you want to write native code (this has recently been added to the allowed list of APIs for Store Apps, although MSDN isn't updated yet).
I am using a 3rd party rest api to query data and display it in my app. I have to perform a task like at night 12 approx. it will perform a background task to query data from rest api and update live tile and generate notification. I would like to use only C# only for this task. I don't know what will be best approach to do this task. But I using below code to perform background task to do this which is not working. Not sure why?
BackgroundTaskBuilder taskBuilder = new BackgroundTaskBuilder();
taskBuilder.Name = taskName;
SystemTrigger trigger = new SystemTrigger(SystemTriggerType.InternetAvailable, false);
taskBuilder.SetTrigger(trigger);
taskBuilder.AddCondition(new SystemCondition(SystemConditionType.InternetAvailable));
taskBuilder.TaskEntryPoint = typeof(BackgroundTask.BackgroundTask).FullName;
taskBuilder.Register();
and from background task I am querying data and generating toast notification.
Any help why this code is not working or when this task will fire. Is there any better approach to do above task?
Thanks
Regarding the code you have not working...
For Windows Phone 8.1 unlike Windows 8\8.1, you are required to call BackgroundExecutionManager.RequestAccessAsync() (search MSDN\internet) for ANY background task before registering task(s) whereas in Windows this is only required for some tasks. Make sure your code calls this and validate the returned value before registering your background task(s).
Regarding knowing if your task "worked"...
It's a good idea to have the background task implementation run (IBackgroundTask::Run()) independent of the trigger\conditions you've set to ensure it performs without issue by debugging it. See instructions in the following link: http://msdn.microsoft.com/en-US/library/windows/apps/xaml/jj542416.aspx.
Regarding your use of SystemConditionType.InternetAvailable...
I'm not 100% about this but I'm pretty certain this will be redundant given you already have a SystemTriggerType.InternetAvailable. I don't know of a situation where the trigger would fire but the condition wouldn't be true.
Regarding the requirement you've mentioned...
If I understand your requirement correctly you have different options here:
If your app is a Windows Phone XAML app that need to run based on time, I would recommend either TimeTrigger or MaintenanceTrigger triggers (as opposed to the SystemTrigger). These are both Background Tasks. For general info on Background Tasks and links to the TimeTrigger and MaintenanceTrigger documentation see this MSDN link: http://msdn.microsoft.com/en-US/library/windows/apps/xaml/hh977056.aspx.
If your app is a Windows Phone Silverlight 8.0 app you can use Background Agents, specifically either PeriodicTask or ResourceIntensiveTask. See the links posted by others or search the MSDN\internet for more info.
If your app is a Windows Phone Silverlight 8.1 app you can use the option in either 1 or 2 above.
I think you should try using PeriodicTask. Also consider the constraints mentioned in the link.
create one class with output Type :Windows Runtime Component
and put your Class that inheritance from IBackroundTask so this work
if you use from emulator for launching app, i think your app for register task not active in emulator.
I have a requirement where I have to call a service in background after every let say 1 hour to get some informations from server. I am working on JavaScript Metro Application. I have tried the background task and used Time Trigger and I have scheduled it to get triggered in every 15 minutes. It get called first time and then it is never called. I didn't close the background task because I want it to run all the time and call the service at scheduled time.
I have used the Microsoft Background task sample for reference.
Please tell me what should be the best approach to call a service in background.
How to use Time Trigger and Why Time Trigger doesn't get called after first time?
Please share code sample or walkthrough if any.
Thanks
First thing you should do is to close the background task properly as instructed in the documentation - if your tasks don't behave nicely, platform might suspend and refuse to run them for some time. You should let the platform handle triggering of the events based on the triggers and conditions you define instead of trying to bend the system. Also, remember that there's CPU and data usage quotas for background tasks present, one can't do massive amount of processing in background tasks - if the quotas are exceeded, tasks will get suspended. Be also sure that the background task works and doesn't throw errors.
In general, my recommendation is that one shouldn't rely solely on background tasks to fetch the information since it's not guaranteed that they manage to do it on time, so better to prepare for downloading the needed data in the foreground app as well. This obviously depends on the use case: if the data fetched in background tasks is not critical but more like nice-to-have, there's much less to worry about.
The TimeTrigger requires the app being added to the lock screen (see docs), but I guess you already meet this requirement since you've managed to get the task running once.
For debugging the background tasks, please take a look at Event Viewer, see detailed instructions. That page also contains some tips about common problems. The Event Viewer entry mentioned in that document is often a valuable resource for figuring out problems with the bg task execution. My guess is that you'll see errors there related to not closing the task properly.