[Dev-luatex] Lua states and \dump

Hans Hagen pragma at wxs.nl
Tue Sep 25 11:53:56 CEST 2007


Jonathan Sauer wrote:

>> there is no control over the lua 
>> end of the game; also, when using much data, in practice the 
>> garbage collectors will bring down your system (so slow that 
>> one will abort the job);
> 
> Interesting. In what use cases did you observe this behaviour?

extensive use of the token callback is one i remember, and a previous 
implementation of node callbacks passes tables instead of userdata which 
was also slow (has to do with the moment the collector steps in); by now 
i have developped a kind of feeling where/how to speed up things

>> luatex kind of assumes modern memory management
> 
> This is surely a given, since LuaTeX runs on Unix and Windows.
> 
>> and machines with memort in the gig range
> 
> This I think is a bit optimistic and IMO limits the usefulness of
> LuaTeX. Especially since TeX has much lower requirements.

sure, but luatex is not tex; for large jobs (say a couple of hundred 
pages with many advanced open type fonts, many graphics, color, 
hyperlinks or whatever takes memory) topping at of 400-500 meg is not 
uncommon and given todays machines we find that acceptable; it also 
depends on what kind of trickery one does

> The problem is not caching, but that LuaTeX, when accessing the bytecode
> register, has overwritten almost all memory (the first 12 bytes of each
> 16 byte block) with zeros. This is the result of the buffer overflow.

sure, and that need to be fixed; however, the kind of message (and 
controling that) is for later

hans

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