How to solve Memory Fragmentation

As you suggest, Doug Lea's malloc might work well. It's cross platform and it has been used in shipping code. At the very least, it should be easy to integrate into your code for testing.

Having worked in fixed memory environments for a number of years, this situation is certainly a problem, even in non-fixed environments. We have found that the CRT allocators tend to stink pretty bad in terms of performance (speed, efficiency of wasted space, etc). I firmly believe that if you have extensive need of a good memory allocator over a long period of time, you should write your own (or see if something like dlmalloc will work). The trick is getting something written that works with your allocation patterns, and that has more to do with memory management efficiency as almost anything else.

Give dlmalloc a try. I definitely give it a thumbs up. It's fairly tunable as well, so you might be able to get more efficiency by changing some of the compile time options.

Honestly, you shouldn't depend on things "going away" with new OS implementations. A service pack, patch, or another new OS N years later might make the problem worse. Again, for applications that demand a robust memory manager, don't use the stock versions that are available with your compiler. Find one that works for your situation. Start with dlmalloc and tune it to see if you can get the behavior that works best for your situation.