sweep failed to find exact end of memory

Pavel Krivanek squeak1 at continentalbrno.cz
Wed Feb 21 20:14:05 UTC 2007


Hi Avi,

I think that you should set the memory limit for the Squeak VM for
now. It seems that it avoids this crashes. 40GB swap and 700MB memory
limit - no crash. Not perfect but better than random crashes.

Cheers,
-- Pavel

On 2/21/07, Avi Bryant <avi at dabbledb.com> wrote:
> On 2/21/07, tim Rowledge <tim at rowledge.org> wrote:
> >
> > On 21-Feb-07, at 10:58 AM, Avi Bryant wrote:
> >
> > > On 2/21/07, tim Rowledge <tim at rowledge.org> wrote:
> > >
> > >> It's an old issue; look up assorted reports of problems with > 2Gb
> > >> pointers. The VM code is mostly written under the assumption that
> > >> singed integers suffice for pointers and we really need to fix that.
> > >> It's an issue of available time.
> > >
> > > Do you have an estimate, hopefully under 1 million euros, of what it
> > > would take to fix this?
> >
> > That's a distressingly difficult question to answer. I bet there are
> > some nasty hacks one could do that would 'fix' it on the basis of
> > forcing the C compiler to do signed-unsigned conversions but... I
> > never trust a C compiler. Aside from Slang code there are of course
> > the primitives and platform code that would be indirectly affected,
> > if only at the level of "I have change this decl to stop an oodleplex
> > of compiler warnings obscuring a real problem". There's also a
> > boatload of VMMaker patches needing proper integration anyway and it
> > would stupid not to do them as well.
> >
> > I'd love to say, "oh a week" but long experience suggests that the
> > truth is normally "double the digits and up the unit" so probably
> > 'two months' is higher in the truthiness scale.
>
> Avoiding hacks and warnings and integrating VMMaker patches are all
> laudable things, but do you even have two months to spare, funded or
> no?  What would it take to get a temporary fix to this bug, however
> ugly?  I've seen it myself and can be a bit of a showstopper if you
> like to work with large images.  We could certainly pay for a week of
> someone's time to do this if that was an option.
>
> Avi
>
>



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