[Mono-list] GdiPlus NullReferenceException

[A Rafael D Teixeira]

libgdiplus simply iniatilizes the needed fields and then mallocs enough
memory for the buffer and returns. Probably malloc is failling to return
the buffer, because it probably isn't thread-safe, and no guarding is
being done on it from what I could check in the sources bitmap.cs
(System.Drawing) and bitmap.c (libgdiplus).

Please post a bug at our bugzilla, for someone better acquainted to go
after it.
(http://bugzilla.ximian.com/enter_bug.cgi?product=Mono%3A+Class%20Libraries)

HIH,


On Wed, 2005-02-16 at 05:40, Yury Serdyuk wrote:
> Hi !
> 
> NullReferenceException is thrown when trying to launch GDI application which 
> uses a lot of threads :
> 
> 
> using System;
> using System.Threading;
> using System.Drawing;
> 
> public class TestGDIPlus  {
>  public static void Main( string[] args ) {
>   int nThreads = int.Parse( args [0] );
>   
>   for ( int i = 0; i < nThreads; i++ ) {
>    Thread t = new Thread( new ThreadStart( TestGDIPlus.Run ) );
>    t.Start();
>   }
>  }
> 
>  public static void Run() {
>   Bitmap bmp = new Bitmap ( 1000, 1000, 
>                   System.Drawing.Imaging.PixelFormat.Format32bppArgb );
>  }
> }
> 
> We run it as
> 
> 
> mono /path/to/TestGDIPlus.exe 8
> 
> 
> Actual Results:
> It throws this exception for each thread
> 
> Unhandled Exception: System.NullReferenceException: Object reference not 
> set to an instance of an object
> in (unmanaged) (wrapper managed-to-native) 
> System.Drawing.GDIPlus:GdipCreateBitmapFromScan0 
> (int,int,int,System.Drawing.Imaging.PixelFormat,intptr,intptr&)
> in <0x00004> (wrapper managed-to-native) 
> System.Drawing.GDIPlus:GdipCreateBitmapFromScan0 
> (int,int,int,System.Drawing.Imaging.PixelFormat,intptr,intptr&)
> in <0x00058> System.Drawing.Bitmap:.ctor 
> (int,int,System.Drawing.Imaging.PixelFormat)
> in <0x0006f> (wrapper remoting-invoke-with-check) 
> System.Drawing.Bitmap:.ctor (int,int,System.Drawing.Imaging.PixelFormat)
> in <0x00036> TestGDIPlus:Run ()
> in <0x0005f> (wrapper delegate-invoke) 
> System.MulticastDelegate:invoke_void ()
> 
> or this one
> [serdyuk@itk-104 tmp]$ mono TestGDIPlus.exe 8
> 
> Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object
> in (unmanaged) System.Drawing.Bitmap:.ctor (int,int,System.Drawing.Imaging.PixelFormat)
> 
> This failure is occured only occasionally,
> so one needs to try run program multiply ones,
> as 
> 
> > [serdyuk@itk-104 tmp]$ mono TestGDIPlus.exe 8 [serdyuk@itk-104 tmp]$ 
> > mono TestGDIPlus.exe 8 [serdyuk@itk-104 tmp]$ mono TestGDIPlus.exe 8 
> > [serdyuk@itk-104 tmp]$ mono TestGDIPlus.exe 8 [serdyuk@itk-104 tmp]$ 
> > mono TestGDIPlus.exe 8 Unhandled Exception: 
> > System.NullReferenceException: Object reference not set to an instance 
> > of an object in (unmanaged) System.Drawing.Bitmap:.ctor 
> > (int,int,System.Drawing.Imaging.PixelFormat) [serdyuk@itk-104 tmp]$
> 
> 
> We have tested under Mono 1.0.5 ( libgdiplus-1.0.5 ) and
> Mono 1.1.3 ( libgdiplus-1.1.3 ) with the same result.
> We have used two diffrent glib-2.0 libraries -
> 
> 2.2.1 and  2.4.7 .
> 
> Please, help.
> 
> Thanks.
> 
> Yury Serdyuk.
> 
> 
> 
> 
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-- 
Rafael "Monoman" Teixeira 
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