Re: GC crashes

[Paul Pogonyshev <pogonyshev@gmx.net>]

Nick Roberts wrote:

>  > > Please do -- I know there is a memory corruption issue somewhere but
>  > > so far nobody's been able to identify under what circumstances they
>  > > happen.
>  >
>  > Somebody with a very fast machine with lots of RAM and lots of spare
>  > time could try to run Emacs under Valgrind.
>
> Have you actually tried this?

No, it was just a random idea.

> I can't get it to work with Emacs and the documentation says:
>
> doco> Emacs is known not to work with Valgrind because Emacs has its own
> doco> memory-management scheme. Emacs works fine if you build it using the
> doco> standard malloc/free routines.

I didn't know this.

> Recently I downloaded Valgrind 2.2.0, and this now works with temacs where
> previously (2.0.0) it ended with a segmentation fault.
>
> This runs like a dog though, and you need either a supercomputer or a lot
> of patience.

Programs under Valgrind run horribly slowly, but nevertheless I consider
Valgrind invaluable.  Under Valgrind your chances of spotting memory
corruption and the line it happens at go up like some 100 times (of course
it cannot notice if you write within allocated memory, but still to a
wrong place.)

Jan D. wrote:

> From Valgrind documentation:
>
>    Programs which are known not to work are:
>      * emacs starts up but immediately concludes it is out of memory and
>        aborts. Emacs has it's own memory-management scheme, but I don't
>        understand why this should interact so badly with Valgrind. Emacs
>        works fine if you build it to use the standard malloc/free
>        routines.

Then maybe someone should build it to use the standard malloc/free routines
and try?  (Yes, yes I should do it myself instead of bogging everybody else,
but I don't have that much CPU time and I have not seen the infamous memory
corruption yet, so I'm not that curious.)

Paul