Re: [gtk-list] Re: how can I trust glib when it has so many mem leaks?

[Michael Babcock <mbabcock la creatureshop henson com>]

andrew@cogent.ca wrote:
> 
> Michael Babcock writes:
>  > > They aren't really leaks in glib, glib just keeps chunks of memory around
>  > > and recycles them. This makes it run a lot faster. The memory is never
>  > > released to the operating system, just back to glib. So you should just
>  > > ignore everything ccmalloc and friends report for glib.
>  >
>  > Arrrgh! I hate it when programs do this! X used to do this and it was
>  > extremely annoying. You had to restart your X server every so often
>  > because its memory usage would just grow and grow and never shrink. If
>  > you ran a graphically intense program that made X allocate a lot of
>  > pixmaps and your X server grew to 30 MB, then, that was it, it stays at
>  > 30 MB till the end of time (or until you restart the X server). I think
>  > Emacs used to do this as well.
> [...]
>  > We need a way to disable this and tell glib to use the normal system
>  > malloc and free. I'd also be interested in some benchmarks about how
>  > much of a difference this makes for real gtk programs. I didn't notice
>  > any big difference in speed when my X and Emacs binaries were changed to
>  > use the system malloc. The latest malloc in glibc is actually pretty
>  > efficient and I think already does some sort of pooling itself.
> 
> Most operating systems that I have used do not implement a malloc/free
> combination that will shrink the process data space on a free() call.
> The system malloc would in fact cause your process to reach a *higher*
> high water mark and stay there, because of both (potential) free list
> fragmentation and the header overhead associated with each allocated
> chunk.

Well on I my system, according to ps axm, it certainly does show the
process size shrinking with free(). And I definitely noticed
improvements when I had a compiled X to use system free() instead of its
own NOP.

I'm running Debian 2.1 with glibc 2.0, but I first noticed this a couple
years ago.

--
Michael Babcock
Jim Henson's Creature Shop - Los Angeles
mbabcock@la.creatureshop.henson.com