Re: etex and pdftex have diverging memory constraints?

Am 27.08.25 um 15:45 schrieb jfbu:
> I forgot to say I am on a 64bit system.

I also used a 64bit system

>
> I have confirmed that the limits (which are close to one another with etex slightly highter than pdftex) are about half the value of main_memory parameter in texmf.cnf.
>
> This parameter is referred to in a comment there as "words of inimemory available; "
>
> On my system its value is 5000000.

I have the same setting

Herbert


>
> Perhaps you have a higher setting or are on a 32bit machine and then the limit is at about main_memory (I can't check).
>
> Kind regards
>
> Jean-François
>
>
>> Le 27 août 2025 à 15:42, Herbert Voss <[email protected]> a écrit :
>>
>>
>>
>> Am 27.08.25 um 15:15 schrieb jfbu via tex-live:
>>> Hi,
>>>
>>> Sorry if this is very basic, but I always thought the sole difference between etex and pdftex is that the former works to produce a dvi and the latter a pdf.
>>>
>>> So, I was surprised to discover (or perhaps I observed that years ago and forgot) that pdftex has slightly more constrained memory constraints on macro expansion.
>>>
>>> Here is a test file testxintLength.tex
>>>
>>> ----
>>> \input xintkernel.sty
>>> \edef\x{\romannumeral\xintreplicate{%
>>> 2492679%
>>> }{F}}
>>> \expandafter\xintLength\expandafter{\x}
>>> \bye
>>> ----
>>>
>>> (the code creates a macro \x expanding to 2492679 F's then attempts to measure how many F's there are).
>>>
>>> Compilation with etex succeeds  (even with 2492694 in place of 2492679).
>>>
>>> $ etex testxintLength.tex
>>> This is pdfTeX, Version 3.141592653-2.6-1.40.28 (TeX Live 2025) (preloaded format=etex)
>>>   restricted \write18 enabled.
>>> entering extended mode
>>> (./testxintLength.tex (./xintkernel.sty) [1] )
>>> Output written on testxintLength.dvi (1 page, 216 bytes).
>>> Transcript written on testxintLength.log.
>>>
>>> But compilation with pdftex fails.
>>>
>>> $ pdftex testxintLength
>>> This is pdfTeX, Version 3.141592653-2.6-1.40.28 (TeX Live 2025) (preloaded format=pdftex)
>>>   restricted \write18 enabled.
>>> entering extended mode
>>> (./testxintLength.tex (./xintkernel.sty)
>>> ! TeX capacity exceeded, sorry [main memory size=5000000].
>>> <inserted text> 2492679
>>>                          \xintlength ...xint_c_i \xint_c_ \xint_bye \relax                                                     l.5 \expandafter\xintLength\expandafter{\x}
>>>                                              !  ==> Fatal error occurred, no output PDF file produced!
>>> Transcript written on testxintLength.log.
>> I cannot see it with an up-to-date TL2025 (macOS):
>>
>> voss>mist:$ pdfetex  xyz.tex
>> This is pdfTeX, Version 3.141592653-2.6-1.40.28 (TeX Live 2025) (preloaded format=pdfetex)
>>   restricted \write18 enabled.
>> entering extended mode
>> (./xyz.tex (/usr/local/texlive/2025/texmf-dist/tex/generic/xint/xintkernel.sty)
>>   [1{/usr/local/texlive/2025/texmf-var/fonts/map/pdftex/updmap/pdftex.map}] )</u
>> sr/local/texlive/2025/texmf-dist/fonts/type1/public/amsfonts/cm/cmr10.pfb>
>> Output written on xyz.pdf (1 page, 9876 bytes).
>> Transcript written on xyz.log.
>>
>> Herbert