On Sun, 19 Jan 2025 at 19:32, luigi scarso wrote:

On Sun, 19 Jan 2025 at 11:37, Petr Olsak wrote:

...

Hello

I am testing new luahbtex and comparing it with luatex because I am considering to set OpTeX with luahbtex engine instead luatex in TeXlive 2025. I have found a difference between lautex and luahbtex behavior which I am unable to explain why. The difference is shown only when huge number of fonts are downloaded by luaotfload and only with selected fonts from internet saved to ~/texmf/fonts. And it manifests only as a little delay (with luahbtex) during dlownloading the fonts to PDF at the end of the document visible if you are watching at the terminal. The PDF result is equal, but I am worried that there is a hidden bug in luahbtex because the difference is unexpected.

I teseted this with OpTeX macros, they never use mode=harf. So I expect the same behavior with both engines. The example for testing is somewhat more complicated and it is exactly described at

https://tex.stackexchange.com/questions/735071/

The main question is: why luatex behaves correctly (with no delay during downolading fonts) but luahbtex presents a delay in given cases? Where is the difference? Can the luatex developers explain this?

Thank you

Petr Olsak

under linux /usr/bin/time always reports luahbtex slower of about 5seconds, but I was not able to find why /where.

-- luigi

Using gprofng https://sourceware.org/binutils/wiki/gprofng I can see that luahbtex spends a relevant time on sweeplist, which means that the lua gc plays an important role here. -- luigi

On 2025-01-20 at 15:26:47 +0100, Petr Olsak wrote:

Thank you very much for testing.

I didn't use such tools. I am watching the terminal when fonts are downloaded (at the end of the document) and I notice the delay per each Besley fonts downloaded from ~/texmf. Sure, it is observable. It looks like waiting for some kind of time limit.

Unfortunately, questions remains: why behavior of Lua garbage collector differs in luatex and luahbtex when the programs have to do the same?

When we copy the fonts from ~/texmf/fonts to current directory:

   cp ~/texmf/fonts/opentype/besley/* .

and run the test, then the unwanted delay with luahbtex disappears. It seems that this has something to do with file searching from TeXmf tree. Garbage collector behavior differs when files are in in different locations?

To trace file searching you can set the environment variable KPATHSEA_DEBUG=32 Regards, Reinhard -- ------------------------------------------------------------------ Reinhard Kotucha Phone: +49-511-3373112 Marschnerstr. 25 D-30167 Hannover mailto:reinhard.kotucha@gmx.de ------------------------------------------------------------------

One answer by Michal Vlasak was given at https://tex.stackexchange.com/questions/735071/ This answer implies that the problem sits in luaotfload code, no in luahbtex binary. Thank you everyone for addressing this issue. Petr Olsak On 1/20/25 11:12, luigi scarso wrote:

On Sun, 19 Jan 2025 at 19:32, luigi scarso wrote:

On Sun, 19 Jan 2025 at 11:37, Petr Olsak wrote:

Hello

I am testing new luahbtex and comparing it with luatex because I am considering to set OpTeX with luahbtex engine instead luatex in TeXlive 2025. I have found a difference between lautex and luahbtex behavior which I am unable to explain why. The difference is shown only when huge number of fonts are downloaded by luaotfload and only with selected fonts from internet saved to ~/texmf/fonts. And it manifests only as a little delay (with luahbtex) during dlownloading the fonts to PDF at the end of the document visible if you are watching at the terminal. The PDF result is equal, but I am worried that there is a hidden bug in luahbtex because the difference is unexpected.

I teseted this with OpTeX macros, they never use mode=harf. So I expect the same behavior with both engines. The example for testing is somewhat more complicated and it is exactly described at

https://tex.stackexchange.com/questions/735071/

The main question is: why luatex behaves correctly (with no delay during downolading fonts) but luahbtex presents a delay in given cases? Where is the difference? Can the luatex developers explain this?

Thank you

Petr Olsak

under linux /usr/bin/time always reports  luahbtex slower of about 5seconds, but  I was not able to find why /where.

-- luigi

Using gprofng https://sourceware.org/binutils/wiki/gprofng I can see that luahbtex spends a relevant time on sweeplist, which means that the lua gc  plays an important role here.

-- luigi