[NTG-pdftex] Bug#458059:

Taco Hoekwater taco at elvenkind.com
Wed May 28 00:21:28 CEST 2008


Hi Frank, Stijn,

Frank Küster wrote:
> Dear TeX(-k) people, dear pdfTeX team,
> 
> late last year Norbert Preining already asked on the TeXk list about a
> problem encountered in Debian, namely a TeX capacity exceeded error on
> grouping levels. Nobody could help back then, but now someone started to
> analyse this further (many thanks, Stijn!).  So could you please (again)
> have a look?
> 
>>
>> Why aren't these quarterword/halfword bounds configurable?

They simply cannot be configurable at runtime because that would be too
late, the entire memory structure depends on these sizes.

> There is a configuration variable nest_size level, but it doesn't seem
> to help in this case: The attached file gives an error
> 
> ! TeX capacity exceeded, sorry [grouping levels=255].
> 
> although my texmf.cnf has nest_size=500.
> 
> Should/can we change max_quarterword, or are there side effects?  

Technically, at compile time we could have max_quarterword=65535 and
even max_halfword=2^30 on all modern platforms, but it more or less 
requires switching to the memory_word structure used by Omega/
Aleph/Luatex for efficiency reasons.

Also, such a change is not something to be undertaken lightly. I've done
that for luatex and iirc there were a few small, subtle side-effects 
that took me entire days to hunt down. Definately a bad idea at last
minute before texlive 2008, and therefore IMO probably not worth the
trouble at all (for pdftex).

> Or should the grouping levels instead use halfword? Or would you like to do
> it in a completely different way?  This is a real life problem which
> affects building the PostgreSQL documentatin.

In any case, we should try running the test with aleph or luatex to be
sure but I (at least half-)expect that the actual limit will not matter,
and that it simply will never be large enough due to some form of
recursion. I can try this tomorrow, will let you know then unless
someone beats me to it.

Best wishes,
Taco



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