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My Delphi6 program crashes because the TotalAddrSpace (THeapStatus) at some point hits the 2GB level, upon which it crashes. I have been able to increase the limit the 4GB level (using {$SetPEFlags $20}), but that only delays the eventual crash.

The problem is that the TotalUncommitted memory keeps increasing for some reason, while the TotalCommitted memory and also the TotalAllocated memory nicely stabilize at an acceptable level (about 550 MB).

I cannot quite figure out WHY the TotalUncommitted memory keeps increasing and eventually makes the TotalAddrSpace hit the 2GB (now: 4GB) level and the program crashes.

In the program I use many dynamic arrays, whose length I increase or reduce regularly with a simple adjustment via the SetLength command. Does this regular increasing/decreasing of dynamic arrays in this way effectively lead to an increase-beyond-bounds of the TotalUncommitted memory?

Any advice or insight is very much appreciated.

Also if you know of a general mechanism to somehow actively decrease the TotalUncommitted memory ...

David Heffernan
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Remco Litjens
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2 Answers2

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Thanks for all help!!

My problem turned out to be one of Heap Fragmentation (or my understanding of it).

I used Setlength to increase/decrease, upon need, a dynamic array always in steps of 5 positions. Given the size of each array element, this apparently lead the OS to reserve much more memory than actually needed, which made the Heap.TotalUncommited grow without bounds, as did the Heap. TotalAddrSpace.

I tried different step sizes to see the impact. With a somewhat bigger step size the problem vanished.

Remco Litjens
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I most strongly suggest you run a special build that has MemCheck included. It's a really great tool to detect memory leaks in your application. More modern Delphi versions have some of this built in (in part thanks to FastMem), but this one has been around since the first Delphi versions and works great on versions 5,6,7.

Stijn Sanders
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