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Re: Windows XP memory limitation? [message #37324 is a reply to message #37261]

Tue, 09 December 2003 17:13

Rick Towler
Messages: 821
Registered: August 1998

Senior Member

"David Yip" wrote in message...

> I understand your point about MFC vs console apps due to the loading
> of DLLs. Though in the scenario I'm describing, I can allocate 10
> times the amount of memory in a C program than under IDL while IDL is
> in it's crash state. If IDL can't get 120MB of contiguous memory from
> the OS then why can a C program get 1200MB under the same conditions?
> I might not have made it clear that I leave IDLDE up after it crashes
> out with the error. I then go to another window and run the C program
> to allocate memory.

It isn't the fact that a MFC app is running but that there are limits on the
amount of contiguous RAM a MFC app can allocate. IDL is built as a win32
app with MFC. It runs into these limits. Your simple C program isn't. It
doesn't run into these limits. Like Karl said, compile your simple C
program as a MFC application and then try it.

-Rick

>
> David
>
> "Karl Schultz" wrote in message ...
>> "David Yip" wrote in message...
>>> Thanks everyone for the responses. Unfortunately none of them worked.
>>> Contrary to what RSI says, there must be a built in memory limitation
>>> or bug in IDL. I'm running 6.0 by the way. Once IDL crashes out with
>>> the memory error, if I type in "BYTARR(120000000)" in the command
>>> window I get "Unable to allocate memory: to make array." Even though
>>> I still should have about 2GB of RAM available. I'm using the /3GB
>>> flag in XP Pro. But if I try to allocate the same amount of memory in
>>> C using "malloc(120000000)" it works just fine. This is while IDL is
>>> in it's crash state. So there is that much available memory available
>>> in the system. In fact if I use "malloc(1200000000)" in C it still
>>> works. That's 10 times the amount of memory that fails under IDL
>>> under the same conditions.
>>
>> There's still a big difference in the largest contiguous block of memory
>> that you can allocate from a stand-alone C program, a Win32 application,
and
>> a Win32 application with MFC. If you build your C test program as a
Win32
>> app with MFC, I doubt that it will be able to allocate a contiguous
block as
>> big as a simple console app can.
>>
>> You may also want to read the thread "Memory Headaches" posted to this
>> newsgroup starting Aug 1, 2002. There is a lot more detail in the
thread
>> and some mention of some tools you can use to determine what is
fragmenting
>> your memory space.
>>
>> IDL has no self-imposed memory limitations that might be responsible for
>> your observations.
>>
>> Karl

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[Message index]

		Windows XP memory limitation? By: dcw_yip on Thu, 04 December 2003 15:01
		Re: Windows XP memory limitation? By: dcw_yip on Wed, 10 December 2003 11:39
		Re: Windows XP memory limitation? By: Karl Schultz on Tue, 09 December 2003 18:03
		Re: Windows XP memory limitation? By: Rick Towler on Tue, 09 December 2003 17:13
		Re: Windows XP memory limitation? By: dcw_yip on Tue, 09 December 2003 16:11

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