# How to expand TeX's “main memory size”? (pgfplots memory overload)

I'm compiling one pretty simple LaTeX file with few dozen of `pgfplots`. Now, I can compile part by part, but am unable to compile it all at once. I really need good precision for all those plots (noise plots) and would like to avoid decimating graphs more. When I run compile, I get this error message:

``````[...] TeX capacity exceeded, sorry [main memory size=3000000].
``````

Is there a way to avoid this message somehow? How am I supposed to use `pgfplots` if I can't plot couple dozen of figures with it without having TeX overloaded? How to expand TeX memory size, please?

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The `pgfplots` package can be particularly heavy on TeX's memory, especially if you are creating plots with lots of data points. Indeed, there is a section in the `pgfplots` manual about expanding TeX's memory. However, that does not mean that expanding TeX's memory is the best solution. Instead, I would recommend using the 'externalization' approach (section 7.1 of the `pgfplots` manual).

The idea of externalization is to compile each plot as a separate TeX job. This leads to a graphic which can be used in the main job. Thus each plot has its own memory requirement, separate from all of the other plots. This usually avoids needing to make TeX's memory bigger. At the same time, the resulting files can be kept between TeX runs, which will speed up compilation for the second and subsequent runs. The latest version of the externalization system needs you to do two things. First, you put

``````\usepgfplotslibrary{external}
\tikzexternalize
``````

in your preamble, to turn the system on. Secondly, you will need to enable 'shell escape'. This is done at the command line by adding the `-shell-escape` switch:

``````pdflatex -shell-escape <filename>
``````

The same can be done in LaTeX editors: there is usually a place in the settings for this type of thing. I'll just add that shell escape does has some security implications: use only with documents that you trust!

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I should probably say that I saw it coming. I had the feeling that "expanding the memory size" is not the answer, and externalization works flawlessly - plus, every following `pdflatex` run is ridiculously faster! Thanks! ...I should only find a way now to forward `-shell-escape` from `rubber --pdf` command that I'm using to `pdflatex`... –  user1996 Dec 30 '10 at 9:59
Also, try the `lualatex` compiler which appears to dynamically allocate more memory if it needs it. –  Sharpie Apr 20 '11 at 4:44
Is there a more general solution that is not limited to pgf? –  Brandon Kuczenski Nov 16 '11 at 7:29
@joseph-wright, this is great, but now I change some of my pgfplots and they don't get updated automatically when compiling? It seems it's still using some old compiled figure. How do I force it to re-compile? –  perr0 Jan 16 '13 at 4:17
For everyone wondering why their images won't be updated after re-running `pdflatex` using the `-shell-escape` option: For every `tikzpicture` an extra `.pdf` file is created. Either delete the file, so it will be recreated next time you run `pdflatex` or put a `\tikzset{external/force remake}` somewhere in your document. –  Lars Jun 6 '13 at 15:49

In TeX Live, you can modify `texmf.cnf` (the one in `/some/path/to/texlive/2010/texmf.cnf`):

``````main_memory = 3000000
``````

See comments in `/some/path/to/texlive/2010/texmf/web2c/texmf.cnf` for details.

Then run the following command as root to recreate the format files:

``````fmtutil-sys --all
``````
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@Edin: your correction is wrong. The file mentioned by Leo Liu is the one to modify, as it's not touched by any TeX Live update. –  egreg May 4 '11 at 8:41
Thanks @egrep. In general things like that should not be modified directly but pointed out in a comment. –  Martin Scharrer May 4 '11 at 10:20
The `/some/path/to/texlive/2010/texmf/web2c/texmf.cnf` is the official config file which will be overwritten in an update. It should not be modified. Instead the `/some/path/to/texlive/2010/texmf.cnf` should be used to change all settings which are different from the default. This is pointed out in the comments of the main `web2c/texmf.cnf` config file, which maybe is what Leo Lio meant in his last sentence. –  Martin Scharrer May 4 '11 at 10:23

after trying all the options (changing texmf.cnf file, etc.) I found on the web, the only one that worked for me was to use lualatex. This is the simplest and more elegant way to do it. Lualatex is available in the Texlive distribution by default.

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see macosx-tex.576846.n2.nabble.com/Lua-td6030741.html for instructions on using lualatex on a mac ::: note: in `pdfLuaLatex.engine` you may need to change `pdflualatex -synctex=1 "\$1"` to `lualatex -synctex=1 "\$1"` –  C. Reed Jan 4 '13 at 13:19

Every now and then I have the same problem when compiling certain files. Of course, I have forgotten every time how I solved it in the past. Then, I google and I am getting to this page. Next, I remember that I landed on this page for several times, but, unfortunately, the answers did'nt help me in the past for my kind of problem. To break that Groundhog Day circle, I write down this answer which may help myself (for the next circle) and hopefully other people. The bad news is that it works only (?) for `MikTeX` users.

``````pdflatex --enable-write18 --extra-mem-bot=10000000 --synctex=1 <filename>
``````

You may replace `10000000` by another ridiculous high number.

For illustration some example log entries:

Failing example without the extra memory:

``````21229 strings out of 493921
360228 string characters out of 3152094
3000000 words of memory out of 3000000
24030 multiletter control sequences out of 15000+200000
49729 words of font info for 45 fonts, out of 3000000 for 9000
841 hyphenation exceptions out of 8191
``````

Working example with `--extra-mem-bot=10000000`:

``````23652 strings out of 493921
401787 string characters out of 3152094
10571134 words of memory out of 13000000
24308 multiletter control sequences out of 15000+200000
49729 words of font info for 45 fonts, out of 3000000 for 9000
841 hyphenation exceptions out of 8191
``````

Working example with `--extra-mem-bot=100000000`:

``````23652 strings out of 493921
401787 string characters out of 3152094
100571134 words of memory out of 103000000
24308 multiletter control sequences out of 15000+200000
49729 words of font info for 45 fonts, out of 3000000 for 9000
841 hyphenation exceptions out of 8191
``````

I guess that my example in truth needed `571134` words of memory (and the the rest is eaten up for fun).

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