Re: [BLACKBOX] Illegal Memory Access with Windows 7 - Update

From: [at]} <Chris>
Date: Sat, 17 Aug 2013 08:36:05 +0930

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> -----Original Message-----
> From: BlackBox [mailto:BLACKBOX{([at]})nowhere.xy
> Skulski
> Sent: Saturday, 17 August 2013 12:20 AM
> To: BLACKBOX{([at]})nowhere.xy
> Subject: Re: [BLACKBOX] Illegal Memory Access with Windows 7 - Update
>
> > Because the test asks for 1000 random allocations of average size 250
> > MByte, no chance!
>
> Why no chance? If "no chance", then the allocation should never succeed.
> But it does succeed from time to time. Most of the time it does not.
>
> I should rephrase my question. Fundamentally, the computer is
> deterministic. You ask for 800 MB and you should either always get it or
> never get it. But it looks like you you are getting it with certain
> probability. So I am asking, what are the hidden variables that govern the
> "yes/no" result?
>

In a word - fragmentation. There might be more than 250MByte of *total*
memory available in the system but not 250Mbyte of *contiguous* memory (as
needed by an array) at that time. It depends on how efficiently the garbage
collector is cleaning up.

I don't know whether it is true or not but I heard rumours that at one time
Microsoft had about 300 people working on the development of the .NET
garbage collector. It certainly is very sophisticated.

For more detailed information see:

http://msdn.microsoft.com/en-us/library/0xy59wtx.aspx

or for a basic overview see:

http://blogs.telerik.com/justteam/posts/13-04-02/understanding-net-garbage-c
ollection

Regards,
Chris

Chris Burrows
CFB Software
http://

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Received on Sat Aug 17 2013 - 01:06:05 UTC