我一直在尝试使用外部 PGFPlot 和 TikZ，因为我一直遇到内存不足的问题，似乎将图形外部化为单独的 pdf 进行缓存是推荐的解决方案。但每当我尝试外部化文档时，我都会遇到错误。
错误：
Package tikz Error: Sorry, the system call 'xelatex -halt-on-error -interactix -shell-escape'. Sometimes it is also named 'write 18' or something like that.
当我放弃尝试外部化时错误就消失了，但这不是我的目标。
代码：
\documentclass[margin=2cm]{article}
\usepackage{pgfplots}
\usepackage{pgfplotstable}
\pgfplotsset{compat=newest}
\usepgfplotslibrary{groupplots}
\usepgfplotslibrary{units}
\usepgfplotslibrary{external} % Comment out to make it run without error
\tikzexternalize[prefix=cache/]{main} % Comment out to make it run without error
\usepackage{tikz}
\usetikzlibrary{external} % Comment out to make it run without error
\usetikzlibrary{pgfplots.external} % Comment out to make it run without error
\usepackage[binary-units=true]{siunitx}
\begin{document}
\begin{figure}
\begin{tikzpicture}
\begin{groupplot}[
group style={
group size=2 by 1,
horizontal sep=40pt,
vertical sep=20pt,
},
x unit=\si{\byte},
y unit=\si{\second},
]
\nextgroupplot
\addplot {x};
\nextgroupplot
\addplot {x^3};
\end{groupplot}
\end{tikzpicture}
\caption{Text describing the plots.}
\label{plot:graphs}
\end{figure}
Look at plot \ref{plot:graphs} for details.
\end{document}
日志文件（完整日志这里)：
===== 'mode=convert with system call': Invoking 'xelatex -halt-on-error -intera
ction=batchmode -jobname "cache/main-figure0" "main"' ========
runsystem(xelatex -halt-on-error -interaction=batchmode -jobname "cache/main-fi
gure0" "main")...disabled (restricted).
\openout3 = `main.auxlock'.
! Package tikz Error: Sorry, the system call 'xelatex -halt-on-error -interacti
on=batchmode -jobname "cache/main-figure0" "main"' did NOT result in a usable o
utput file 'cache/main-figure0' (expected one of .pdf:.jpg:.jpeg:.png:.bmp:). P
lease verify that you have enabled system calls. For pdflatex, this is 'pdflate
x -shell-escape'. Sometimes it is also named 'write 18' or something like that.
Or maybe the command simply failed? Error messages can be found in 'cache/main
-figure0.log'. If you continue now, I'll try to typeset the picture.
See the tikz package documentation for explanation.
Type H <return> for immediate help.
...
l.34 \end{tikzpicture}
This error message was generated by an \errmessage
command, so I can't give any explicit help.
Pretend that you're Hercule Poirot: Examine all clues,
and deduce the truth by order and method.
Overfull \hbox (127.35689pt too wide) in paragraph at lines 17--35
[][]
[]
LaTeX Warning: Reference `plot:graphs' on page 1 undefined on input line 39.
[1
] (main.aux)
LaTeX Warning: There were undefined references.
LaTeX Warning: Label(s) may have changed. Rerun to get cross-references right.
)
此错误仅发生在具有 TikZ 和 PGFPlot 资源的子文件中。\ref即使它输出为 pdf，它也会破坏我的整个文档。任何帮助都将不胜感激。
答案1
评论太长了
您只需加载两个external库中的一个。目前，TikZ v3.1.9a 和 PGFPlots v1.18.1 的版本应该相同，因此这只是个人喜好问题。
当我编译时
% used PGFPlots v1.18.1
\documentclass[border=5pt,varwidth]{standalone}
\usepackage{pgfplots}
\usepgfplotslibrary{
groupplots,
external,
}
\tikzexternalize[prefix=cache/]
\begin{document}
\begin{tikzpicture}
\begin{groupplot}[
group style={
group size=2 by 1,
horizontal sep=40pt,
vertical sep=20pt,
},
xlabel=B,
ylabel=s,
]
\nextgroupplot
\addplot {x};
\nextgroupplot
\addplot {x^3};
\end{groupplot}
\end{tikzpicture}
\end{document}
使用最新的 MiKTeX 中的 LuaLaTeX，我可以从日志中看到\tikzexternal调用
===== 'mode=convert with system call': Invoking 'lualatex -shell-escape -halt-o
n-error -interaction=batchmode -jobname "cache/minimal-figure0" "\def\tikzexter
nalrealjob{minimal}\input{minimal}"' ========
其工作正常，即我没有收到任何错误消息。
关于\ref。这里不清楚你的意思。要么你想让它返回一个数字，但为此figure缺少环境。或者你想让它返回图，但为此你必须将移动到命令\label后面\addplot。之后你需要编译三次才能看到预期的结果，因为在第一次运行中环境axis被外部化并且\label被写入 AUX 文件，在第二次运行中 crossref 被外部化然后在第三次运行后显示出来。