I created a Background Application for Windows IoT Core on a Raspberry Pi 3. It is to become a hub application for a "smart home remote" (Nuimo) which uses BLE GATT to communicate.
The odd thing is that after a short time of running, the application simply stops responding and also drags Visual Studio along. VS then responds very slowly, has trouble detaching from the debugging process, shows "waiting for a background task to complete" dialog. However, no exceptions seem to be thrown (I enabled breaking on all exceptions). This makes it very difficult to find the cause of the problem.
I tried:
removing parts of the application
enabling breaking on all exceptions
combining multiple events coming from the BLE device to prevent flooding the application with events.
Unfortunately none of this helped.
Relevant documentation I read:
https://developer.microsoft.com/en-us/windows/iot/docs/backgroundapplications
https://learn.microsoft.com/en-us/windows/uwp/devices-sensors/bluetooth-dev-faq
https://learn.microsoft.com/en-us/windows/uwp/devices-sensors/gatt-client
https://learn.microsoft.com/en-us/windows/uwp/launch-resume/access-sensors-and-devices-from-a-background-task
Therefore I'm wondering whether anybody could share experience and hints where to look for the issue.
The code is at https://github.com/wind-rider/nuimo-hub and https://github.com/wind-rider/nuimo-windows (too much to post here since I don't know what part the issue is in)
Update: in the process explorer (via Windows Device Portal) I see that suddenly the memory used by the app drops when it stops responding, but its process (backgroundTaskHost.exe) is not immediately gone. It seems that somehow the Background App is unloaded, and that Visual Studio doesn't notice it since the host process is not shut down?
Now - how to know why the task is unloaded?
I assume that a Windows IoT Core background app is a special kind of background task that is not limited by the resource constraints applying to background tasks for "normal UWP apps"? Quote: "Background Applications are applications that have no direct UI. Once deployed and configured, these applications launch at machine startup and run continuously without any process lifetime management resource use limitations." (from https://developer.microsoft.com/en-us/windows/iot/docs/backgroundapplications)
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Im using this guide "automating the testing of windows 8 apps" to test my windows store app
http://blogs.msdn.com/b/windowsappdev/archive/2012/09/04/automating-the-testing-of-windows-8-apps.aspx
Unfortunaltely Ive run into a problem, I need to know when my app closes (crashes) or when it goes into suspended mode, to log that info, and I want the launcher to be able to know the application has stopped , unfortunately iApplicationActionManager, does not have that method. And IPackageDebugSettings which is used to change the application suspend and resume states does not have a readable current state property (afaik)
Is there any way to do this?
We have a native GUI application which runs on a windows machine, and recently we have found out that the application terminates unexpectedly. After days I have found that this is happening because the application is run by explorer.exe and it gets killed unexpectedly, random somehow, so it causes termination of all child processes including our application.
Is there a way to invoke/call our app as system process (not with explorer.exe)?
Also assume that application/user has administrator access too.
Thanks in advance.
Killing explorer does not in general kill other processes. This is very easy to verify yourself by killing explorer from the task manager. Notice that other processes stay alive when you kill explorer. Something else is killing your process.
If killing explorer leads to your process dying, then the obvious explanation is that something in your process is leading to its death. In other words the problem is most likely in your code, and you need to work out what that problem is.
Also note that explorer isn't really a special "system process" as such. It's just a normal process that that runs under the logged on user's token.
You may need to give some hand of a OS services, then run the service as admin(run as system boot), then start he application from the service ,this will ensures you the app will started as admin and without the explorer.exe(as child)
We have automatically started service which in some cases spends a lot of the time loading necessary data, let's say 10 minutes. During this time it works as expected (processing some huge data files required to start). I report the progess by C++ SetServiceStatus function, it is working fine.
This service is not dependent on anything and has only one dependency which is again our own service. It is started after those 10 minutes, it needs the first "server" service to be fully running to accept the requests.
I thought that windows would start all other automatic services (in less then 10 minutes as usually) and then start working normally but system is completely blocked during startup (i can't login to computer or ping the computer) until this one specific service is started (reports SERVICE_RUNNING by SetServiceStatus). When out service completely starts, the other missing system services (required for network, remote desktop, whatever, it's quite random) are also started. Is this normal behaviour? Why are non-depending processes (as remote desktop, network connections, etc.) waiting for this process? Am I missing something?
I tried to add some dependencies to postpone the startup of my service but I ended up with many dependencies and behaviour still somehow random (as order of services is random). Sometimes I was able to login but for example Start button started working only after those 10 minutes when my service was started. I am not sure what is "the last service" to depend on and what services to include to my depend-list and on some computers this services can be disabled and it can bring new problems... so I don't like this solution very much.
Another option was Delayed start option for our service. This should start service when all other automatic services are running. Well, this works fine, windows boots, computer running and responding, our service is started, but the performance is very bad, many times slower than usually, it seems that delayed started services have much lower priority or something like that.
My only current solution is to report to system that my service is running (by SetServiceStatus function), but to continue loading (this works, I tested it). But then we have problem with our dependent service as it needs to be started when the first one is really ready. It can be solved but I still wonder how is this possible and if there is something I could use to keep the current state of automatic started service which reports "started" when it is really fully started and prepared to work. Thanks for any ideas.
Set SERVICE_RUNNING as soon as possible, and then continue processing in background. Make your other service resilient to the first service being in a running state, but not yet ready to service.
The longer the service is in the starting state the more problems we get from different windows versions.
I have a Windows service written in CPP that I start manually. The service starts up just fine and works ok. However we have recently noticed in the Windows Services GUI that the service shows in the Starting state. Upon examining the Event Viewer it clearly shows that the service has entered the Running state.
Anyone got any nuggets of gold on this one?
Thanks.
The problem turned out to be an unaccounted for call to the SCM to start the service. Deleted the line and the problem went away.
I have a C++ Win32 application that was written as a Windows GUI project, and now I'm trying to figure out to make it into a Service / GUI hybrid. I understand that a Windows Service cannot / should not have a user interface. But allow me to explain what I have so far and what I'm shooting for.
WHAT I HAVE NOW is a windows application. When it is run it places an icon in the system tray that you can double-click on to open up the GUI. The purpose of this application is to process files located in a specified directory on a nightly schedule. The GUI consists of the following:
A button to start an unscheduled scan/process manually.
A button to open a dialog for modifying settings.
A List Box for displaying status messages sent from the processing thread.
A custom drawn window for displaying image data (the file processing includes the creation and saving of images).
A status bar - while a process is not running, it shows a countdown to the next scheduled scan. During a scan it also provides some status feedback, including a progress bar.
WHAT I'M SHOOTING FOR is a service that will run on boot-up and not require a user to login. This would consist of the scheduled file processing. However, when a user logs in I would still like the tray icon to be loaded and allow them to open up a GUI as I described above to monitor the current state of the service, change settings, start a scan manually, and monitor the progress of a scan.
I'm sure that I have seen applications like this - that function as a service even when I'm not logged in, but still give me a user interface to work with once I do log in.
I'm thinking that instead of having a single multi-threaded application that sends messages to the GUI thread from the processing thread, I need two applications - a Service to perform the processing and a GUI application to provide visual feedback from the Service and also send messages to the Service (for example, to start a scan manually). But I am new to Windows Services and have no idea how this is done.
It is also possible that I'm completely off base and a Service is not what I'm looking for at all.
Any help / ideas / suggestions would be greatly appreciated! Thank you.
You can't do this as a service.
You'll need to make your Windows Service as a normal service application. This will startup on system startup, and run the entire time the system is up.
You'd then make a completely separate GUI application, which "talks" to the service. This can be set to run when a user logs in, in the user's account.
In order to make them "talk" to each other, you'll need to use some form of IPC. Since these run on the same system (but in different accounts, typically), named pipes or sockets both work quite well.
There is a simple way of doing it.
You can’t have the service access any user’s session (session 1,2,3..) since services are isolated and can access session 0 only. This is a change from 2011.
You should write a win32 program to be launched by your service per each user who logs in using https://msdn.microsoft.com/en-us/library/windows/desktop/ms682429(v=vs.85).aspx
The service can continue performing any task that isn’t user specific.