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tin - 18 Nov 2006 18:56 GMT

hi, i have an exe that holds a very large Dictionary collection that would
takes about 2.5G in total. the machine has 4G RAM.

if i load the entire collection within an EXE, i would get
outofmemoryexception when it uses up to about 1.5G RAM. however, if i split
the collection into 2 seperate EXE, one can load up to 1.2G and another 1.3G
without any problems even if they both run at the sametime. the machine
still has about 500 MB RAM free afterward.

ideally, i like to have just one EXE to hold all 2.5G data ... is it
possible? any idea?

thanks!

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Willy Denoyette [MVP] - 19 Nov 2006 13:24 GMT

> hi, i have an exe that holds a very large Dictionary collection that would
> takes about 2.5G in total. the machine has 4G RAM.
[quoted text clipped - 9 lines]
>
> thanks!

32 bit Windows applications only have access to 2GB (or up to 3GB on /4GT RAM tuning enabled
systems) user virtual address space, the process VAS is fragmented as a result of loading
the modules (DLL's) into the address space. The result is that you won't ever find a
contiguous area of memory larger than say ~1.5GB, when Windows Forms is loaded, you won't
even find such an area.
Note also that it's not possible you had two Dictionaries of 1.2 and 1.3GB loaded at the
same time, guess one of these was freed by the GC at the time the second was created.
Another thing to keep in mind is that .NET (the current versions on both 32 and 64 bit
Windows) don't allow you to create objects larger than 2GB, so you will have to change your
design.

Willy.

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tin - 19 Nov 2006 22:41 GMT

" Note also that it's not possible you had two Dictionaries of 1.2 and 1.3GB
loaded at the
same time, guess one of these was freed by the GC at the time the second was
created. "

that's only when the 2 are in the same appl right? i was loading them with
2 different exe. and from the task manager, it's clear that one holds 1.2g
and one holds 1.3g.

so as long as i don't load a dictionary more than 1.5G within the same appl,
it should be ok right?

thank you very much.

> > hi, i have an exe that holds a very large Dictionary collection that would
> > takes about 2.5G in total. the machine has 4G RAM.
[quoted text clipped - 22 lines]
>
> Willy.

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Willy Denoyette [MVP] - 19 Nov 2006 23:28 GMT

>" Note also that it's not possible you had two Dictionaries of 1.2 and 1.3GB
> loaded at the
[quoted text clipped - 4 lines]
> 2 different exe. and from the task manager, it's clear that one holds 1.2g
> and one holds 1.3g.

Yep, each process has 2GB VAS.

> so as long as i don't load a dictionary more than 1.5G within the same appl,
> it should be ok right?

Not necessarily, suffice to load a third party DLL that is mapped somewhere in the middle
of the VAS to have your contiguous area further fragmented. On 32bit windows, you should
always be prepared to incur OOM exceptions when allocating such huge objects.

Willy.

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tin - 20 Nov 2006 00:20 GMT

i see. thanks for the quick and great info!

> >" Note also that it's not possible you had two Dictionaries of 1.2 and 1.3GB
> > loaded at the
[quoted text clipped - 14 lines]
>
> Willy.

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Ben Voigt - 05 Dec 2006 23:03 GMT

> hi, i have an exe that holds a very large Dictionary collection that would
> takes about 2.5G in total. the machine has 4G RAM.
[quoted text clipped - 9 lines]
> ideally, i like to have just one EXE to hold all 2.5G data ... is it
> possible? any idea?

search for "Address Windowing Extensions"

> thanks!

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outofmemoryexception

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