Re: Lost or corrupted `undo-tree' history

[Stefan Monnier <monnier@iro.umontreal.ca>]

> default value and garbage collecting starts immediately. However, the memory
> consumption of Emacs does not fall back to 500MB, but rather goes down to
> only e.g. 6GB, which afterwards are never ever reclaimed.

As Eli mentioned, this is considered normal and not a leak.
It only becomes a leak when the unused memory held cannot be reused
for anything.

> If I repeat the test, the memory consumption would immediately
> continue to grow off 6GB further as if those 6GB are not reused and
> are somehow stuck holding something that cannot be reclaimed anymore.

This is more serious, OTOH.
It might indeed be symptom of a leak.  Of course, it can also come from
a problem of fragmentation, or a number of other undesirables effects.

Delaying GC (by raising `gc-cons-threshold`) tends to both increase the
time it takes to a perform a GC cycle and also increase fragmentation.
This is why Emacs's default setting errs on the side of GC'ing rather
more often than less often.


        Stefan