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Advice on solving OutOfMemoryExceptions for CF

Answer 1

A:

"getting a useful snapshot of the GC heap using RPM is hard" Maybe you can try some profiler for .NET CF, I have heard of EQATEC profiler if that helps you with the threads.

My approach to avoiding OOM errors is to not design for an MDI(Multiple Document Interface) type application, have only one form in memory) and setting to null all objects after they have been used (specially the "heavier ones" like XMLDocument).

Also, this might be relevant: http://stackoverflow.com/questions/297697/outofmemoryexception-when-creating-a-large-bitmap-in-cf-net

Abhijeet Kashnia 2010-01-11 12:35:31

Caching the forms and instead of closing/recreating them on the fly results in a much much smoother transition when switching forms. Therefor I want to keep my design with the heavily cached forms. I've used EQATEC profiler before, but as I recall, it doesn't log memory footprints. The first line of their product description would confirm this: "The EQATEC Profiler is a code profiler, not a memory profiler."

Frank Razenberg 2010-01-12 23:30:09

Answer 2

+1 A:

If you're using the same images on multiple forms, you should consider to keep those Bitmaps as static variables in a class that is accessible by all your forms.

public class AppBitmaps
{
  public static Bitmap LogoBitmap = new Bitmap(...);

  public static Bitmap ButtonBitmap = new Bitmap(...);
}

public class Form1
{
  public Form1()
  {
    this.Control1.Image = AppBitmaps.LogoBitmap;
  }
}

That way you only keep one instance of that image in memory, which should cut down the overall memory usage.

tomlog 2010-01-11 14:29:01

Thanks for your comment. In the old situation, I did many calls to ResourceManager.GetObject() to load my bitmaps. Since I needed very minor localization and scaling options (i.e. sometimes a different image WVGA/VGA resolutions), everything was obtained through a static helper function. As such it was very easy to add a caching mechanism like you proposed in this helper function, which led to saving a few bitmaps in memory. For now it'll suffice, so thanks!

Frank Razenberg 2010-01-12 23:27:55

Answer 3

A:

If that is a snap shot of your application working at full tilt then I would suggest:

It's another app that is running
Your app pinvokes into an unmanaged memory leak
The OS (customised CE?) has a leak
or something else

Quibblesome 2010-01-12 00:41:17

In fact, my device has lots of RAM available. I'm using a standard WM6 professional device, have none but the essential processes running, and my code has only very few P/Invoke functions which are usually called just once. I think this instead has to do with the 32MB address space limit that winmo apps need to deal with.

Frank Razenberg 2010-01-12 23:33:05

I thought that limit didn't apply on WM6? I know it definitely does on WM5. Either way I forgot that you also need to add the size of the GC Heap and various CLR caches to your score (that you can get from the profiler). Then the size of the .dlls (uncompressed) ontop of that to get your final score.

Quibblesome 2010-01-13 10:19:09

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Advice on solving OutOfMemoryExceptions for CF

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