The following code snippet illustrates a memory leak when opening XPS files. If you run it and watch the task manager, it will grow and not release memory until the app exits.
‘****** Console application BEGINS.
Module Main Const DefaultTestFilePath As String = 'D:\Test.xps' Const DefaultLoopRuns As Integer = 1000 Public Sub Main(ByVal Args As String()) Dim PathToTestXps As String = DefaultTestFilePath Dim NumberOfLoops As Integer = DefaultLoopRuns If (Args.Count >= 1) Then PathToTestXps = Args(0) If (Args.Count >= 2) Then NumberOfLoops = CInt(Args(1)) Console.Clear() Console.WriteLine('Start - {0}', GC.GetTotalMemory(True)) For LoopCount As Integer = 1 To NumberOfLoops Console.CursorLeft = 0 Console.Write('Loop {0:d5}', LoopCount) ' The more complex the XPS document and the more loops, the more memory is lost. Using XPSItem As New Windows.Xps.Packaging.XpsDocument(PathToTestXps, System.IO.FileAccess.Read) Dim FixedDocSequence As Windows.Documents.FixedDocumentSequence ' This line leaks a chunk of memory each time, when commented out it does not. FixedDocSequence = XPSItem.GetFixedDocumentSequence End Using Next Console.WriteLine() GC.Collect() ' This line has no effect, I think the memory that has leaked is unmanaged (C++ XPS internals). Console.WriteLine('Complete - {0}', GC.GetTotalMemory(True)) Console.WriteLine('Loop complete but memory not released, will release when app exits (press a key to exit).') Console.ReadKey() End Sub End Module ‘****** Console application ENDS.
The reason it loops a thousand times is because my code processes lots of files and leaks memory quickly forcing an OutOfMemoryException. Forcing Garbage Collection does not work (I suspect it is an unmanaged chunk of memory in the XPS internals).
The code was originally in another thread and class but has been simplified to this.
Any help greatly appreciated.
Ryan
Well, I found it. It IS a bug in the framework and to work around it you add a call to UpdateLayout. Using statement can be changed to the following to provide a fix;