[luatex] LuaLaTeX's performance

[Pander]

On 2010-11-19 21:15, Khaled Hosny wrote:
> On Fri, Nov 19, 2010 at 08:52:39PM +0100, Pander wrote:
>> Hi all,
>>
>> I'm new here so please forgive my lacking knowledge of LuaLaTeX.
>>
>> I'm compiling a font catalogue in XeLaTeX but am more and more compelled
>> to switch over to LuaLaTeX because of better font support.
>>
>> At the moment, only two things are obstructing this. First is missing
>> support for polyglossia, but as I gathered, people are working on this.
> 
> AFAIK no one is actually working on that.

Some German and some French developer were/are/planning to work on this
I read on comp.text.tex and de.comp.text.tex

>> The other thing is the performance. Now it could be that the current
>> executable is not optimised and is doing loads of debug logging.
>> However, my font catalogue is a good test case.
>>
>> XeLaTeX can process it in two parts because other it runs out of memory.
>> However, LuaLaTeX is hitting some sort of performance barrier halfway my
>> document and after using up almost 6 GB of memory I have to kill off the
>> process. Please see attached screenshots of memory usage.
> 
> LuaTeX will happily use all memory available to it (unlike most other
> TeX engines which have hard-coded memory limit, IIUC). The current font
> loading code is not very memory efficient and for certain fonts e.g.
> fonts with huge kerning tables (some font developers like to say their
> fonts have tens of thousands of kerning pairs, like if it is a feature
> or something). I think post-texlive2010 releases of luatex made some
> progress in this area, but I'm not sure if Hans started making use of it
> or not.
> 
>> How can LuaLaTeX's performance be improved? Is the current executable in
>> TLContrib a debug build with maximum logging?
> 
> I don't think so, I don't think it would be that relevant either. If you
> can isolate the most offending fonts it might help in identifying and
> possibly fixing the cause.

It it difficult to isolate since gradually memory gets eaten. Can I run
it with profiling or logging to report which font is using how much memory?

Regards,

Pander

> Regards,
>  Khaled
>