Re: Who wants to have some fun memory debugging?

[grauzone]

Wild guess: there's a false pointer, that keeps one element in the list 
from being collected, and because the list-prev pointers are still 
there, all following elements won't be collected either in consequence.

If I had time, I'd try two experiments:
1. before freeing everything, reset the prev field of each element; if 
this makes the leak go away, my guess would probably be right
2. use the destructor (Data had to be a class) to keep track of how many 
elements are actually freed by the GC (just a thread safe counter, 
that's incremented in the ctor and decremented in the dtor); just to 
find out if this is an internal GC problem, or if you have too many live 
garbage