Slice range must fall within the size of the buffer.

[jtamaska]

Hi,

I am pretty baffled about this problem. I have a Graph binded with an array of Chartcollections. The charts are filled paralelly. Sometimes, quite randomly, I get this exception. In this case i had three plots displayed:

System.ArgumentOutOfRangeException was unhandled
  HResult=-2146233086
  Message=Slice range must fall within the size of the buffer.
Parameter name: length
Actual value was 3.
  Source=NationalInstruments.Common
  ParamName=length
  StackTrace:
       at NationalInstruments.Restricted.Guard`1.Satisfies(Boolean condition, Func`4 exceptionCreator, String format, Object[] args)
       at NationalInstruments.Restricted.NIValidation.IsInRange[T](Guard`1 guard, Boolean isInRange, String format, Object[] args)
       at NationalInstruments.DataInfrastructure.Primitives.RawDataStore`1.Slice(Int32 startIndex, Int32 length)
       at NationalInstruments.DataInfrastructure.Buffer`1.Slice(Int32 startIndex, Int32 length, Func`2 traitFilter)
       at NationalInstruments.DataInfrastructure.Buffer`1.NationalInstruments.DataInfrastructure.IBuffer.Slice(Int32 startIndex, Int32 length)
       at NationalInstruments.Controls.Internal.DefaultAdjusterStep.a(IDictionary`2 A_0)
       at NationalInstruments.Controls.Internal.DefaultAdjusterStep.c(IDictionary`2 A_0)
       at NationalInstruments.Controls.Internal.DefaultPipelineDataProcessor.a(DefaultDataItemDescription[] A_0)
       at NationalInstruments.Controls.Internal.DefaultPipelineDataProcessor.a()
       at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
       at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
       at System.Windows.Threading.DispatcherOperation.InvokeImpl()
       at System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Windows.Threading.DispatcherOperation.Invoke()
       at System.Windows.Threading.Dispatcher.ProcessQueue()
       at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
       at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
       at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
       at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
       at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
       at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
       at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
       at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
       at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
       at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
       at System.Windows.Threading.Dispatcher.Run()
       at System.Windows.Application.RunDispatcher(Object ignore)
       at System.Windows.Application.RunInternal(Window window)
       at System.Windows.Application.Run(Window window)
       at System.Windows.Application.Run()
       at MyProject.FinalTest.Specific.GUI.App.Main() in c:\Sandbox\Specific2\MyProject.FinalTest.Specific.GUI\obj\Debug\App.g.cs:line 0
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException:

I dont even know where to start looking! Can someone please give me some pointers? Thanks!

[phansen]

By "The charts are filled parallelly", I take it that you are always appending to all the charts at the same time? Or do you mean appending to the charts on a different thread? (If the latter, because the chart collections are not thread-safe, you would need to marshal appends to the UI thread.)

Unfortunately, I was not able to reproduce the slice error you are seeing. I used three ChartCollection<double> instances, and tested appending the same number of samples to each and different number of samples to each from a dispatcher timer, using one or two vertical axes. If you could provide a small sample application that reproduces the error, it would greatly simplify debugging your issue.

As a workaround, you may want to use the suggestions from this answer about disappearing charts. This will prevent the slice method from being called, which should avoid the issue entirely.

[jtamaska · Accepted solution]

I found the problem!

I had a timer calling the method, which updated the plots from a queue. If there were too many signals, the emptying of the queue could take longer  than the next timer call, and two threads tried to acces the charts paralel. I know set the timer inactive for the queue reading and turn it on after, and the problem looks solved!

Thank you for the idea bouncing, it was the direction I needed to start looking!