From: Paul Eggert <eggert@cs.ucla.edu>
To: jan <rtm443x@googlemail.com>
Cc: 41155@debbugs.gnu.org
Subject: bug#41155: 26.3; regexp 99% locks up emacs
Date: Tue, 12 May 2020 13:56:05 -0700 [thread overview]
Message-ID: <facf01fc-7347-d550-4927-641f76f3e1ef@cs.ucla.edu> (raw)
In-Reply-To: <CADJx9LcE5HDdhBsXe1B8kHw6tcG0ABwS_=ddJ2KgFKQcbfqq_w@mail.gmail.com>
> I originally put it down to the regexp being clearly pathalogical
Yes, that's pretty much it. Emacs uses a backtracking matcher and its worst case
performance is exponential. You can even use the matcher to solve Diophantine
integer equations ... verrrryy slowly; see:
http://blog.stevenlevithan.com/archives/algebra-with-regexes
So, don't do that. (Or if you *do* want to do that, fix the matcher - but good
luck with that....)
next prev parent reply other threads:[~2020-05-12 20:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-09 17:31 bug#41155: 26.3; regexp 99% locks up emacs jan via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-05-12 20:56 ` Paul Eggert [this message]
2020-05-12 22:28 ` jan via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-05-13 9:11 ` jan via Bug reports for GNU Emacs, the Swiss army knife of text editors
2020-05-14 4:46 ` Paul Eggert
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