Slowdown (or even error) with files containing a lot of comments

[aeporreca]

Expected Behavior

I think markdown-mode should be able to work with files containing arbitrarily many comments (in my case, the comments are automatically generated by giving the flyspell-mode command flyspell-correct-word-before-point followed by the “Accept (buffer)” menu entry).

Actual Behavior

When opening a Markdown file containing a lot of comments, such as the attached test.txt (I renamed it as .txt since I don’t know how to upload an .md file) and editing the text while the comments are visible on screen, there is a long lag before the result of the text-editing commands becomes apparent. This does not seem to happen if the comments are not visible (e.g., if you have to scroll down to see them).

When the number of comments becomes very large, such as in the attached test2.txt file, the problem becomes even worse, with an (error "Lisp nesting exceeds ‘max-lisp-eval-depth’").

Steps to Reproduce

Open test.txt and edit it, or just open test2.txt, after having renamed them to .md.

Backtrace

• For the slowdown occurring when editing test.txt: according to the Emacs profiler, most of the time seems to be spent inside the markdown-syntax-propertize-comments function.

• See the attached backtrace.txt for the error obtained when opening test2.txt.

Software Versions

• Markdown Mode: version 2.5-dev
• Emacs: 27.1
• OS: macOS Catalina 10.15.6

[syohex]

Sorry belated reply. Please check #543. It fixes only recursive function call issue. I suppose it is difficult to fix slow down issue.

[syohex]

@aeporreca I have merged #543. Could you check latest version ?

[aeporreca]

@syohex, this does indeed solve the recursion issue for me (but not, as you mentioned, the other one).