[Xurinos]

Did anyone else think of CL-PPCRE as they read through the "lisp does not have regular expression support" implications? That was answered by the comparison of elisp to modern Common Lisp, and I wonder if anyone has done any work to make CL-PPCRE work for elisp. In spite of being someone's library, it is much faster than perl's built-in regex support.

There is a point to be made for the idea that you are solving the wrong problem with the log parsing. On the other hand, if you are trying to interface with other developers' popular engines, you may not have a choice.

[jrockway]

Most of those benchmarks are against Perl 5.8, the version of Perl released in 2002. 5.10 had major regexp engine improvements, and 5.12 had minor improvements. Anything is fast when you compare it to 10 years ago.

[btilly]

Furthermore the 5.8 engine is pretty much the 5.6 engine, which was significantly slower than the 5.005 engine. Why the slow-down? Because 5.6 has logic to check when regular expressions are matching slowly, and then to add tracing when it is. This makes many of the exponential slowdowns that Mastering Regular Expressions describes be automatically caught and handled fairly quickly.

The CL-PCRE and Java regular expression engines don't have those somewhat expensive checks, and so are much more likely to encounter catastrophic behavior.

[jrockway]

Yeah, but who cares about real-world code if you have a neat benchmark page? Most of your "users" will never even get to the point of using your package -- after saying how great it is on Reddit, they'll turn on their porn and forget all about it.

OK, maybe I'm too cynical...

[Xurinos]

I actually ran my own tests to see the difference, including tests against hash speed and so forth. But it is good to know there are other benchmarks out there that correlate with what I found, even if older ones. Has anyone published new ones?