Big Session file (4GB) cannot be loaded

Use this forum for questions on how to use .NET Memory Profiler and how to analyse memory usage.
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Joined: Mon May 17, 2010 7:07 am

Big Session file (4GB) cannot be loaded

Post by akraus1 » Tue May 18, 2010 4:57 am


this is rather unfortunate. After waiting for about 20h to load a 4 GB 64 bit dump file I managed to see a little more what was going on. But since the profiler did eat up already 10 GB of memory I though I save the session to disk and restart the profiler. It took ages to save and exit the profiler but finally I have saved from a 3.9 GB dump file a 4.3 GB sesson file to disk.
Now I did start up the profiler a again to load the the session file but *dramatic suspense* I was immediately greeted with an OutOfMemoryException error message. How can this be? I have the 64 bit version on a really good PC with 4 Cores, Windows Server 2008 R2, 16 GB Physical RAM and tons of raid hard disk space?

Alois Kraus

Andreas Suurkuusk
Posts: 1030
Joined: Wed Mar 02, 2005 7:53 pm

Re: Big Session file (4GB) cannot be loaded

Post by Andreas Suurkuusk » Tue May 18, 2010 8:54 pm

Even if you have a lot of RAM, there are still some memory limitations within the .NET Framework, e.g. it's not possible to allocate a managed instance that is bigger than 2 GB. A 4.3 GB session file is a very big session file and I can imagine that it can cause the profiler to allocate large managed instances.

Your problem might be caused by the memory limitation, or that something went wrong when the session file was saved. Is there any possibility that you can provide us with the session file, the memory dump, or preferably both? If it possible, please contact us at, so that I can provide you with information on how to upload the files. The size of session files can usually be reduced significantly when compressing, so hopefully it will be possible for you to upload it.
Best regards,

Andreas Suurkuusk
SciTech Software AB

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