I spend some nights to try to understand the memory usage of the following Python script:
https://bitbucket.org/haypo/misc/src/31bf03ace91db3998981ee56caf80f09c29991f5/memory/python_memleak.py?at=default

It looks like the weird memory usage (aka "memory fragmentation"?) was fixed in Python 3.3.

> This significantly helps fragmentation in programs with dynamic memory usage, e.g. long running programs.

On which programs? The fragmentation of the memory depends a lot on how the program allocates memory. For example, if a program has no "temporary memory peak", it should not be a victim of the memory fragmentation.

To measure the improvment of such memory allocator, more benchmarks (speed and fragmentation) should be run than a single test (memcruch.py included in the test) written to benchmark the allocator.