Malformed HTML can cause pandoc to "hang" never generating output.

[michael-conrad]

~$ pandoc --version
pandoc 2.9.2.1
Compiled with pandoc-types 1.20, texmath 0.12.0.1, skylighting 0.8.3.2
Default user data directory: /home/muksihs/.local/share/pandoc or /home/muksihs/.pandoc
Copyright (C) 2006-2020 John MacFarlane
Web:  https://pandoc.org
This is free software; see the source for copying conditions.
There is no warranty, not even for merchantability or fitness
for a particular purpose.

pandoc -o 2301.md --to=commonmark --from=html 2301.html

Sample malformed HTML which causes hang:

2301.html.tar.gz

[jgm]

I tried this and it didn't hang; it completed in 6 seconds (which is slow, admittedly) with 2MB maximum memory use.

[michael-conrad]

Sorry, that's the wrong file (have a lot of files).
Check this one.

0101.html.tar.gz

It is currently sitting at:

PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND  

24266 muksihs   20   0  1.000t  53432  35832 R 100.0  0.2   1:44.97 pandoc   

[jgm]

OK, I fixed the issue; the file now takes 0.13s to convert.

However, some other issues:

• If you go -t commonmark, you'll just get HTML tables, since commonmark doesn't have a table syntax.
• You should ideally be able to rectify this by doing -t gfm, which has pipe tables, but something is preventing these tables from rendering as pipe tables. (The problem is the <br> elements which require line breaks: pipe table content must fit on a single line. If you strip out the <br> elements with sed or perl before passing to pandoc, you should get good results.)
• -t markdown will give you decent pandoc markdown tables, but they won't be GitHub-compatible if that's important to you.