Ha! The same bug happened internally at my company. In that case it was a regex matching a URL taking so much CPU as to cause a DOS of a proxy server. I won't be surprised if it's happened to someone here too.
This is very timely, because minutes ago, I made a link to Russ Cox's articles in my Kernighan awk repo:
https://github.com/andychu/bwk
https://swtch.com/~rsc/regexp/regexp1.html
If you are not familiar with this issue, basically Perl popularized bad computer science... "regexes" are not regular languages.
They say that this particular case triggered quadratic behavior, not exponential, but the point is that there is a linear time algorithm to do this.
The file b.c in the awk repo implements the linear time algorithm:
https://github.com/andychu/bwk/blob/master/b.c
(and rsc's site has some nice sample code too, as well as caveats with regard to capturing and so forth)
This is very timely, because minutes ago, I made a link to Russ Cox's articles in my Kernighan awk repo:
https://github.com/andychu/bwk
https://swtch.com/~rsc/regexp/regexp1.html
If you are not familiar with this issue, basically Perl popularized bad computer science... "regexes" are not regular languages.
They say that this particular case triggered quadratic behavior, not exponential, but the point is that there is a linear time algorithm to do this.
The file b.c in the awk repo implements the linear time algorithm:
https://github.com/andychu/bwk/blob/master/b.c
(and rsc's site has some nice sample code too, as well as caveats with regard to capturing and so forth)