# pdflatex.exe on both dualcore-cores?

Is it possible to load pdflatex on both dualcore-cores of my Intel Core2Duo-Processor? At the moment, pdflatex just uses one core while the second core stays idle.

I got a pretty big document of 200 pages with many non-eps-pictures included...

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[3 years later] Since this question has been considered a duplicate in tex.stackexchange.com/questions/136658/…, I would like to point out that documents relying on `tikz` and either `external` lib or `standalone` package may benefit from multiple cores. Perhaps answers should be tracked under the linked question. –  Christian Feuersänger Oct 6 '13 at 14:16

TeX works in a linear way, with little or no room for parallellization. Besides that, `pdflatex` is written in a single-threaded fashion, so that won't be an option.

There are several options to speed-up building times:

1. `draft` does exactly what you expect from it, it produces a draft document: images are excluded, `microtype` is disabled, ...
2. you can use `subfiles` or `subdocs` (both clickable) to only rebuild the relevant parts of your document
3. comment sections you're not adapting at that moment
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The linear nature of the typesetting process is the key: you can't start typesetting at the beginning and middle of a file at the same time! –  Joseph Wright Nov 17 '10 at 12:17
That's true, but I've always felt that it could be possible to do two passes: one to do all macro expansions and collect figures / pictures / `tikz`, then parse those in parallel and in a second pass actually process / typeset all the actual text. But what the possible benefit could be, I don't know, optimization without benchmarking first is useless, so I don't know the actual bottlenecks. And there are probably issues with this idea :). –  Pieter Nov 17 '10 at 12:37
@Pieter: You're falling into the trap of thinking of TeX macros as similar to, for example, C ones. In TeX, you cannot expand the macros without reference to what else is going on (see category codes, verbatim text, etc.). So a scheme as you suggest is fundamentally not possible with the TeX model –  Joseph Wright Nov 17 '10 at 12:40
That's why my first pass is expansion in a linear fashion, as it happens right now. But certain steps (for instance: including an image, which requires information on its dimensions) aren't performed yet, just the state at that moment is saved. Then those saved states are processed in parallel, modulo a dependency check. –  Pieter Nov 17 '10 at 12:45
Certain actions that can be guaranteed to have no side effects (e.g. including a picture stream whose size is already known, embedding fonts, etc.) could indeed be parallelized. However, that would require a complete rewrite of the TeX program (which is written in a very idiosyncratic way, with many global variables etc.), something that AFAIK not even the LuaTeX team plans. –  Philipp Nov 17 '10 at 13:56