I have an existing Silverlight 5 application. I'm adding a page to it to allow users to process mass updates to data in a 3rd party database system. The application currently uses WCF RIA services to communicate to the 3rd party system via SOAP. The functionality of the update is contained in a Workflow 4 application I created and is referenced as an assembly on the server-side of the SL application. Lastly, the application is hosted right now in my local instance of IIS 7.5 running on Windows 7; I'm also debugging with IIS, not the VS dev server.
At the basic level, the application functions as follows:
Select text file
Click "Start" button
Event handler creates an instance of a user-defined Type that keeps track of the batch
Event handler creates a new BackgroundWorker instance and wires up handlers for the DoWork, ProgressChanged, and RunWorkerCompleted events
Event handler calls RunWorkerAsync()
Here's the shortened code for the DoWork event handler, since that's where the majority of the work is done.
private void BwOnDoWork(object sender, DoWorkEventArgs doWorkEventArgs, BatchContainerControl batchProcess)
{
var worker = sender as BackgroundWorker;
// Iterate through each record of data file and call the 'UpdateAddress' function
// of the AddressDomainService which, in turn, executes the Workflow
foreach (var item in batchProcess.FileData)
{
// Check if operation has been cancelled
if (worker.CancellationPending)
{
doWorkEventArgs.Cancel = true;
break;
}
. . .
// Invoke THINKComm.CustomerAddressUpdate Workflow via AddressContext
var invokeOp = _addressDomainContext.UpdateAddress(activityData);
// 'activityData' is an instance of Dictionary<string, string>
invokeOp.Completed += (o, args) => InvokeOpOnCompleted(o, args, batchProcess);
}
}
The handlers for the ProgressChanged and RunWorkerCompleted events, as well as the Completed event of the InvokeOperation instance all, for the most part, update a part of the UI. If you think posting any of that code would be helpful, I'd be happy to update the post.
Speaking of UI, the parts that are updated by the event handlers are two ProgressBar controls - one that tracks the records as they're read from the file and a second one that tracks the records as the update has taken place on the 3rd party database.
Getting to the actual problem...
I've processed files of 10, 100, and 1,000 records with no problem. I then attempted to process a complete file containing ~15,000 records (or 1,907KB of data). The process starts and I can see in the debugger output that the Workflow is being executed. About a quarter of the way through or so, I get an OutOfMemoryException. Here's the stack trace:
at System.ServiceModel.DomainServices.Client.WebDomainClient`1.BeginInvokeCore(InvokeArgs invokeArgs, AsyncCallback callback, Object userState)
at System.ServiceModel.DomainServices.Client.DomainClient.BeginInvoke(InvokeArgs invokeArgs, AsyncCallback callback, Object userState)
at System.ServiceModel.DomainServices.Client.DomainContext.InvokeOperation(String operationName, Type returnType, IDictionary`2 parameters, Boolean hasSideEffects, Action`1 callback, Object userState)
at THINKImportSystem.Web.Address.AddressDomainContext.UpdateAddress(Dictionary`2 activityData)
at THINKImportSystem.BatchProcessPage.BwOnDoWork(Object sender, DoWorkEventArgs doWorkEventArgs, BatchContainerControl batchProcess)
at THINKImportSystem.BatchProcessPage.<>c__DisplayClass10.<StartButtonClick>b__6(Object s, DoWorkEventArgs args)
at System.ComponentModel.BackgroundWorker.OnDoWork(DoWorkEventArgs e)
at System.ComponentModel.BackgroundWorker.OnRun(Object argument)
Then, the JIT debugger pops up with an error of Unhandled Error in Silverlight Application Code:4004 with a message of System.ServiceModel.DomainServices.Client.DomainOperationException: Invoke operation 'UpdateAddress' failed. Error HRESULT E_FAIL has been returned from a call to a COM component.
I should mention that, sometimes, I get the JIT debugger first. I see in the Debug output that threads are still exiting, and then about 10 or 20 seconds later, the VS debugger pops up with the out of memory exception.
My best guess is that, objects somewhere (maybe related to the DomainService?) aren't being released and therefore, memory usage is building. From what I understand, IIS places restrictions on the amount of memory an application can use, but I can't tell if that's the case here or not.
I was thinking that, each time a record in the file is processed, the objects related to it's processing would be released and therefore overall memory usage would be pretty low. But obviously I'm not understanding how everything is being executed!
I was also wondering if using the TPL as opposed to BackgroundWorker would make a difference?
Related
I have a SQL Sever 2008 R2/64-bit database server for which I'm writing some fairly basic scripting utilities with the Sql Server Management Objects (SMO). My project is a 32-bit VS2010 executable written in C#.
Most of the effort has been fairly simple and successful. The only problem I'm having is in the firing of my custom event handler that should be called in response to a Scripting Error.
The Scripter object exposes a ScriptingError event, which I have attempted to leverage thusly:
//srv contains a valid server name
Scripter scrp = new Scripter(srv);
//scrp_ScriptingError is my handler
scrp.ScriptingError += new ScriptingErrorEventHandler(scrp_ScriptingError);
My handler is declared thusly:
static void scrp_ScriptingError(object sender, ScriptingErrorEventArgs e)
{
// my handler goes here, just printing e.Current.Urn to the console
// This is merely representative, have had other things here, but
// the handler never fires
Console.WriteLine(e.Current.Value);
}
All this compiles cleanly.
My code is invoked via simple scrp.Script(urns); where urns is just an array of the database objects being scripted out. Nothing fancy:
try
{
sc = scripter.Script(urns);
}
catch (Exception e)
{
WriteLog(String.Format("Failure during scripting: {0}: Inner exception message (if any): {1}",e.Message,((e.InnerException==null)?"[None]":e.InnerException.Message)));
}
using (System.IO.StreamWriter file = new System.IO.StreamWriter(fileName,true))
{
foreach(String currentLine in sc)
{
file.WriteLine(currentLine);
file.WriteLine("GO");
}
}
The problem is that, no matter what I've tried so far, when errors occur during scripting, my ScriptingError handler never fires.
Even in debug mode within VS2010, when I set a breakpoint within the handler, and fire my scripting code, and know an error will occur, only an exception will be thrown, but the breakpoint in my ScriptingError handler never trips.
I'm in trees-for-forest mode now, not sure what I've done wrong. Am I expecting the wrong things for the ScriptingError handler?
I have searched the MSDN docs on the SMO objects and found virtually nothing on ScriptingError handlers other than the basic API calls themselves, and precious few examples on the Internet. It seems incredibly simple and straightforward to me - just assigning an event handler to the event - but there's some battery-not-included notice I've failed to note.
Pointers to my error are greatly appreciated, with a polite request for minimal brickbats if the error is exceptionally stupid on my part :)
I am not at a pc right know, but I think you should try to set the ContinueScriptingOnError option. Otherwise there would be no reason for SMO to invoke the event, but rather through an exception instead.
I have a Winforms application that schedules some work using a service. The service has a callback that updates the database with the work proceedings.
Now let's say I schedule x work items. After the x work items are all completed, I want to generate an HTML report about the work statistics. I think the only way I can check the work completion of all items is to see their completion statuses in the database.
Can someone tell me how and when I can generate the HTML report? I think I can use a thread to poll the db to see if all work completed and inform UI to generate the report, but don't know how to implement that.
You can use BackgroundWorker component for waiting async task completed. It's easy.
First - drag BackgroundWorker from Toolbox to your form.
Second - when you start processing (e.g. on button click event) add following code:
private void button_Click(object sender, EventArgs e)
{
backgroundWorker1.DoWork += backgroundWorker1_DoWork;
backgroundWorker1.RunWorkerCompleted += backgroundWorker1_RunWorkerCompleted;
backgroundWorker1.RunWorkerAsync();
}
Next - add to DoWork event handler code that starts processing and polling database:
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
// schedule some work
// poll database
}
And last - add RunWorkerCompleted handler, which will run just after DoWork completed (i.e. all tasks updated their state in database):
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
// generate report
}
Thats it. Btw BackgroundWorker could report progress during polling database. Little searching will help you how to do that :)
You can use Task.ContinueWith and Task.Wait
Example: Using Task
Task.ContinueWith:
This extends the initial task. Run immediatly after it finishes
Task.Wait
You would use this if you are running several task that provide the same result be may do so at different times, i.e. fetching same data from different web services.(Just an example).
This will execute as soon as one of the appropriate task successfully finishes.
As part of my App's startup procedure, it checks data integrity, and if it finds a problem it pops up a message to the user telling them that it might take a while to repair things.
I'm showing the message using MessageBox.Show. Because the data check is done from a worker thread, I'm switching over to the UI thread to make that call, and then setting a ManualResetEvent to tell the worker thread when the user has acknowledged the message.
I kick off the data check/load very early in the app's lifecycle from the constructor in the main Application class, by spinning off a worker thread (using the ThreadPool).
When I run with the debugger, and the message is displayed, the app just waits for input. When I run without the debugger, the app terminates after displaying the dialog for 10 seconds.
That 10 seconds is a big clue - it tells me that the OS thinks the app took too long to initialize (the OS kills apps that take too long to start up).
I think that my MessageBox.Show is blocking the UI thread before the App.RootFrameNavigating has a chance to be invoked.
My questions:
Does my diagnosis sound right?
I'd prefer to kick off my data load early, because it is almost entirely IO, except for this Message Box, and the sooner I can get my Model loaded, the better, but do you normally delay your data load until later in the app lifecycle?
Any other ideas/suggestions? I can't guarantee which page will be the start page, because the app could be resuming to any page. I'm also thinking of having the MessageBox.Show delay itself until the app has initialized, perhaps polling away for a flag set by App.RootFrameNavigating - does that make sense?
I think your problem is a result of kicking off the worker thread in the Application constructor. You should use the appropriate life-cycle event, in this case: PhoneApplicationService.Activated Event
So, the solution I've come up with is to still kick off the data load in a worker-thread from the Application's constructor, but in my PhoneService's class ShowDialog method that I invoke to invoke MessageBox.Show, I check to see if the initial navigation has occurred:
private readonly ManualResetEvent _appInitialized = new ManualResetEvent(false);
public void AppInitialized()
{
_appInitialized.Set();
}
public void ShowDialog(string caption, string text, Action<MessageBoxResult> callback, MessageBoxButton button = MessageBoxButton.OKCancel)
{
_appInitialized.WaitOne();
DispatcherHelper.CheckBeginInvokeOnUI(() =>
{
var result = MessageBox.Show(text, caption, button);
if (callback != null)
{
callback(result);
}
});
}
Then in my Application class:
private bool _firstNavigate = true;
private void RootFrameNavigating(object sender, NavigatingCancelEventArgs e)
{
if (_firstNavigate)
{
_firstNavigate = false;
var navigationService = (NavigationService) sender;
navigationService.Navigated += NavigationServiceNavigated;
}
....
private void NavigationServiceNavigated(object sender, NavigationEventArgs e)
{
var navigationService = (NavigationService)sender;
navigationService.Navigated -= NavigationServiceNavigated;
PhoneServices.Current.AppInitialized();
}
Anyone see any issues with this approach? Anyone come up with a better way?
I have a Windows Service that monitors a COM port connected to a vendors hardware. This is a very busy piece of hardware that is constantly polling other devices on the wire (this is a twisted-pair RS485 "network"). My software needs to emulate X number of hardware devices on this wire, so I've got a multi-threaded thing going on with a multi-tiered state machine to keep track of where the communications protocol is at any moment.
Problem is with a Windows Service (this is my first one, BTW) is that you need some debugging to let you know if stuff is working properly. When I was first developing this state machine/multi-thread code I had a windows form with a RichTextBox that displayed the ASCII chars going back-n-forth on the line. Seems like I can't really have that GUI niceness with a service. I tried opening a form in the service via another program that sent the service messages that are received via the OnCustomCommand() handler but it didn't seem to work. I had "Allow service to interact with desktop" checked and everything. I was using the Show() and Hide() methods of my debug form.
I guess I don't need to see all of the individual characters going on the line but man that sure would be nice (I think I really need to see them :-) ). So does anyone have any crazy ideas that could help me out? I don't want to bog down the system with some IPC that isn't meant for the voluminous amount of data that is sure to come through. It will only be very short-term debugging though, just confirmation that the program, the RS485-to-USB dongle, and hardware is all working.
Use OutputDebugString to write to the debugging buffer and then use DebugView to watch it. If you're running on Windows XP or earlier, then you can use PortMon to see the raw bytes going through the serial port. The advantage over a log file is that there's very little overhead, particularly when you're not watching it. You can even run DebugView from another machine and monitor your service remotely.
I dunno if it will work for you, but I always build my services with a extra Main that build them as console app to get debug output.
Edit:
Some example:
class Worker : ServiceBase
{
#if(RELEASE)
/// <summary>
/// The Main Thread where the Service is Run.
/// </summary>
static void Main()
{
ServiceBase.Run(new Worker());
}
#endif
#if(DEBUG)
public static void Main(String[] args)
{
Worker worker = new Worker();
worker.OnStart(null);
Console.ReadLine();
worker.OnStop();
}
#endif
// Other Service code
}
You could write the output to a log file and then use another application to watch that file. This question about "tail" outlines several options for watching log files with windows.
What I usually do when working on a Windows Service is to create it so that it can be run either as a service, or as a plain old command-line application. You can easily check whether you are running as a service by checking Environment.UserInteractive. If this property is true, then you are running from the command line. If the property is false, then you are running as a service. Add this code to Program.cs, and use it where you would normally call ServiceBase.Run(servicesToRun)
/// <summary>Runs the provided service classes.</summary>
/// <param name="servicesToRun">The service classes to run.</param>
/// <param name="args">The command-line arguments to pass to the service classes.</param>
private static void RunServices(IEnumerable<ServiceBase> servicesToRun, IEnumerable args)
{
var serviceBaseType = typeof(ServiceBase);
var onStartMethod = serviceBaseType.GetMethod("OnStart", BindingFlags.Instance | BindingFlags.NonPublic);
foreach (var service in servicesToRun)
{
onStartMethod.Invoke(service, new object[] { args });
Console.WriteLine(service.ServiceName + " started.");
}
Console.WriteLine("Press any key to exit.");
Console.ReadKey();
var onStopMethod = serviceBaseType.GetMethod("OnStop", BindingFlags.Instance | BindingFlags.NonPublic);
foreach (var service in servicesToRun)
{
onStopMethod.Invoke(service, null);
Console.WriteLine(service.ServiceName + " stopped.");
}
}
Now you can debug your service, set breakpoints, anything you want. When you run your application, you'll get a console window, appropriate for displaying console messages, and it will stay open until you hit a key.
I'm answering my own question here. I tried a couple of suggestions here but here's what I ended up doing...
I created a Windows Form application with a single Button and RichTextBox. This application constructed a NamedPipeServerStream on it's end. The Button's job was to send either "debug on" (command 128) or "debug off" (129) to the Windows Service. The initial value was "debug off". When the button was clicked, a command of 128 was sent to the Windows Service to turn debugging on. In the Windows Service this triggered an internal variable to be true, plus it connected to the Form application with a NamedPipeClientStream and started sending characters with a BinaryWriter as they were received or sent on the COM port. On the Form side, a BackgroundWorker was created to WaitForConnection() on the pipe. When it got a connection, a BinaryReader.ReadString() was used to read the data off of the pipe and shoot it to the RichTextBox.
I'm almost there. I'm breaking my pipe when I click the debug button again and a subsequent click doesn't correctly redo the pipe. All in all I'm happy with it. I can post any code if anyone is interested. Thanks for the responses!
We are using the WPF FormattedText object to determine text size in a service that grabs the latest news headlines from an RSS feed. The text retrieved needs to be in a specified canvas size. The service runs the code every 10 seconds and uses up to 2 threads if one takes longer than that. I'm using TaskFactory (which I've overridden the LimitedConcurrencyLevelTaskScheduler to limit to the amount of threads I specified).
This works great, except after several days (the length is variable), we start to get the following exceptions. The same code was working fine before we started using TPL to make it mult-threaded.
I need help figuring out what this is caused by. A few thoughts I'm looking into are: thread collisions holding on to a TTF file, memory issue, the dispatcher (see the stack trace) isn't playing nicely with the TaskFactory, other??
We don't have good profiling setup, but we've looked at the TaskManager when the exception is occurring and memory usage looks normal.
My next attempt is to use the TextBlock object and see if the exception is avoided.
Error Message: The system cannot find the file specified
Error Source: WindowsBase
Error Target Site: UInt16 RegisterClassEx(WNDCLASSEX_D)
Exception Stack Trace:
at MS.Win32.UnsafeNativeMethods.RegisterClassEx(WNDCLASSEX_D wc_d)
at MS.Win32.HwndWrapper..ctor(Int32 classStyle, Int32 style, Int32 exStyle, Int32 x, Int32 y, Int32 width, Int32 height, String name, IntPtr parent, HwndWrapperHook[] hooks)
at System.Windows.Threading.Dispatcher..ctor()
at System.Windows.Threading.Dispatcher.get_CurrentDispatcher()
at System.Windows.Media.TextFormatting.TextFormatter.FromCurrentDispatcher(TextFormattingMode textFormattingMode)
at System.Windows.Media.FormattedText.LineEnumerator..ctor(FormattedText text)
at System.Windows.Media.FormattedText.DrawAndCalculateMetrics(DrawingContext dc, Point drawingOffset, Boolean getBlackBoxMetrics)
at System.Windows.Media.FormattedText.get_Metrics()
at
(my method using the FormattedText, which is in a loop)
private static Size GetTextSize(string txt, Typeface tf, int size)
{
FormattedText ft = new FormattedText(txt, new CultureInfo("en-us"), System.Windows.FlowDirection.LeftToRight, tf, (double)size, System.Windows.Media.Brushes.Black, null, TextFormattingMode.Display);
return new Size { Width = ft.WidthIncludingTrailingWhitespace, Height = ft.Height };
}
EDIT: so far I've tried placing a lock around the code that calls this function, and calling it inside the CurrentDispatcher.Invoke method like so:
return (Size)Dispatcher.CurrentDispatcher.Invoke(new Func<Size>(() =>
{
FormattedText ft = new FormattedText(txt, new CultureInfo("en-us"), System.Windows.FlowDirection.LeftToRight, tf, (double)size, System.Windows.Media.Brushes.Black, null, TextFormattingMode.Display);
return new Size { Width = ft.WidthIncludingTrailingWhitespace, Height = ft.Height };
}));
EDIT: I've found links to others having similar, but not the exact problem.
http://www.eggheadcafe.com/software/aspnet/31783898/problem-creating-an-bitmapsource-from-an-hbitmap-in-threaded-code.aspx ~having a similar problem, but no answers
System.Windows.Media.DrawingVisual.RenderOpen() erroring after a time ~having a similar problem, but no answers
http://connect.microsoft.com/VisualStudio/feedback/details/361469/net-3-5-sp1-breaks-use-of-wpf-under-iis# ~ similar exception, but we're not using 3.5SP1 or IIS 7.
I've also submitted this through the Microsoft Connect site (please vote for it if you are having a similar problem).
https://connect.microsoft.com/WPF/feedback/details/654208/wpf-formattedtext-the-system-cannot-find-the-file-specified-exception-in-a-service
EDIT: Response from Microsoft:
"WPF objects need to be created on Dispatcher threads, not thread-pool threads. We usually recommend dedicating a thread to run the dispatcher loop to service requests to create objects and return
them frozen. Thanks, WPF Team" ~ How would I implement this?
EDIT: final solution thanks to NightDweller
if(Application.Current == null) new Application();
(Size)Application.Current.Dispatcher.CurrentDispatcher.Invoke(new Func<Size>(() =>
{
...});
EDIT: When I deployed the change (new Application();), I got an error logged " Cannot create more than one System.Windows.Application instance in the same AppDomain."
Error Source: PresentationFramework
Error Target Site: Void .ctor()
A shot in the dark:
The stack trace seems to show that WPF does not find a Dispatcher in the thread executing GetTextSize, so it has to create a new one, which involves creating a handle to a window.
Calling this every 10 seconds means 8'640 threads, thus windows per day. According to Mark Russinovich, there is a limit of 32 K windows per session, which may explain the error in RegisterClassEx.
An idea to overcome this is to read the current dispatcher from your main thread and set it in your tasks.
Edit:
I had another look and it looks like one cannot set the Dispatcher of a thread (it's created automatically).
I'm sorry, I am unable to understand what is going on here.
In order to compute the text size, WPF needs a FormattedText instance, which is stored as a member of the Dispatcher class. The existing Dispatchers are stored in a list of weak references. Each one is associated with a specific thread.
Here, it looks like new Dispatcher instances are created many, many times.
So, either the calling thread is new or memory is quite low and the weak references have been discarded.
The first case (new thread) is unlikely as the task scheduler uses the thread pool, which has about 25 threads per core (if I remember correctly), which is not enough to deplete the pool of ATOMs or windows.
In the second case, the depletion of resource is unlikely as the HwndWrapper is IDisposable and the Dispose method takes care of freeing the registered class.
As you already know from the info you provided, All UI elements (FormattedText is one) have to be created on the UI thread.
The code you are looking for is:
return (Size)Application.Current.Dispatcher.CurrentDispatcher.Invoke(new Func<Size>(() =>
{
FormattedText ft = new FormattedText(txt, new CultureInfo("en-us"), System.Windows.FlowDirection.LeftToRight, tf, (double)size, System.Windows.Media.Brushes.Black, null, TextFormattingMode.Display);
return new Size { Width = ft.WidthIncludingTrailingWhitespace, Height = ft.Height };
}));
Notice the Application.Current - you want the "Application" dispatcher which is the dispatcher for the UI thread in WPF applications.
Your current code actually creates a dispatcher for the current thread so you didn't really change the executing thread (see here regarding the dispatcher)
Have you renamed anything? If yes, check that link: WPF Prism: Problem with creating a Shell