How to debug hang?

[David Abrahams]

Hi,

I'm trying to debug some kind of a hang that occurs when I try to use
a font-lock mode I'm developing.  I can't get control back by hitting
`C-g'.  I suspected it was a bad (combinatoric) regexp, but I added
advice before and after re-search-forward that emitted enter/exit
messages, and when the hang occurs I am seeing an exit message, so I'm
guessing that's not it.  I'm quite stumped now; hoping someone can
offer a clue.

Thanks,

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com