# Foldexpr_markdown very slow for some documents #162

Closed
opened this Issue Jan 6, 2015 · 7 comments

Projects
None yet
5 participants

### khughitt commented Jan 6, 2015

 When working on a mixed Markdown/LaTeX document, I noticed after a while the performance of very basic actions like deleting a word or pasting text was becoming very slow. I profiled vim to see what the culprit was, and it turned out the be the vim-markdown (commit 091091f from 2015/01/02) Foldexpr_markdown function. After just a few seconds of profiling and performing basic text manipulation operations on a paragraph of plain-text, Foldexpr_markdown was called over 100,000 times: FUNCTION Foldexpr_markdown() Called 107204 times Total time: 3.945203 Self time: 3.945203 count total (s) self (s) 107204 0.177798 if (a:lnum == 1) let l0 = '' else 107204 0.371518 let l0 = getline(a:lnum-1) 107204 0.095889 endif 107204 0.270002 let l1 = getline(a:lnum) 107204 0.316180 let l2 = getline(a:lnum+1) 107204 0.444422 if l2 =~ '^==\+\s*' " next line is underlined (level 1) return '>1' elseif l2 =~ '^--\+\s*' " next line is underlined (level 2) 72 0.000086 return '>2' elseif l1 =~ '^#' " don't include the section title in the fold return '-1' elseif l0 =~ '^#' " current line starts with hashes return '>'.matchend(l0, '^#\+') else " keep previous foldlevel 107132 0.097830 return '=' endif  To be sure that this was indeed the issue, I disabled vim-markdown folding using let g:vim_markdown_folding_disabled=1 and the issue went away. Unfortunately I am not sure how to reproduce the issue outside of the larger document I am working on, so I cannot pinpoint the cause of the problem. The document is not all that special, except that is contains a couple simple LaTeX equations and images. The image blocks are the most complex bit of LaTeX, and they look something like: \begin{wrapfigure}{r}{0.5\textwidth} \begin{framed}\raggedleft%\centering \vspace{-20pt} \begin{center} \includegraphics[width=1\textwidth]{images/image} \end{center} \vspace{-20pt} \caption{\textbf{text...} text.. more text...} \vspace{-10pt} \end{framed} \end{wrapfigure}  Vim version: VIM - Vi IMproved 7.4 (2013 Aug 10, compiled Dec 27 2014 04:46:10) Included patches: 1-560 I'm sorry I can't provide a more reproducible example. Hopefully this might give you some ideas about the underlying issue, or perhaps someone else with the same problem can help to clarify. Let me know if there is anything else I can do to help track down the issue.

### retrography commented Sep 23, 2015

 @khughitt Are you working on a Pandoc document or similar with a front matter? Is it possible that you have an unclosed YAML front matter in your document. Pandoc, for instance, has a weird front matter that opens with --- and closes with ..., and this plugin won't recognize that. At least for me this was the issue. Even if this is not the case for you, you may want to check to see if there is something in your text that this plugin considers as opening a block, and that is not followed by a bock-closing sign.

### khughitt commented Sep 25, 2015

 @retrography I am indeed using Pandoc to convert the Markdown to PDF, and am including a YAML header. As far as I can tell though, it should be properly closed. The YAML block for the document is: --- bibliography: references.bib header-includes: - \usepackage[font=small,labelfont=bf]{caption} - \usepackage{wrapfig} - \usepackage{framed} - \pagenumbering{gobble} output: pdf_document ---  There is one other instance in the document of a long string of dashes used to create a header item (-----------), and I found one instance of '...' in a comment in the document. It's been a while since I worked on that document, however, and when I tried to reproduce the issue just now I was unable to. I'll re-enable folding though and let you know if I run into the problem again. Feel free to close this issue in the meantime if you would prefer. Thanks!

Contributor

### alexconst commented Feb 1, 2016

 Is there any workaround for this? I'm writing a small script to help me with pandoc-markdown-jekyll (it parses the whole file while making changes along the way with setline) but Foldexpr_markdown takes too much time (~ 15 seconds for a ~ 750 lines file). And it doesn't matter if the frontmatter closure is set to '...' or '---'. I also tried let g:vim_markdown_folding_disabled = 1 in my script but no luck. The only workaround I found so far was using let g:vim_markdown_folding_disabled = 1 in .vimrc. But this disables folding altogether. BTW, Pandoc's YAML closure is valid. More info on this at jgm/pandoc#2668
Collaborator

### shirosaki commented Feb 1, 2016

 :setl foldexpr=0 to disable folding of current buffer. let g:vim_markdown_folding_disabled = 1 at runtime doesn't work.
Contributor

### alexconst commented Feb 1, 2016

 Thanks! That solved it. Just wondering if there is a way to save and restore the foldexpr value in vimscript? I can save the value with let orgfoldexpr=&foldexpr but I'm unable to restore it afterwards.
Collaborator

### shirosaki commented Feb 2, 2016

 &foldexpr seems to be string. setl foldexpr=eval(orgfoldexpr) restores the string value.
Contributor

### alexconst commented Feb 2, 2016

 Works like a charm. Thanks.