3 ms·

I have 5.8.8, and I have 5.14.2. I've also taken the liberty of converting the string of a?'s into a{0,27}. I recognize that you're trying to demonstrate patho

I have 5.8.8, and I have 5.14.2. I've also taken the liberty of converting the string of a?'s into a{0,27}. I recognize that you're trying to demonstrate pathologically bad behavior, but as written, you've got a pathologically bad regex. Note the speed up from 24 & 30 seconds to seven one-thousandths of a second in both cases. Again, I like the idea of a regex engine with different design considerations than Perl's. Your article would have been much better if it has used a class of pathological data with real world examples, and not used contrived examples that I rewrote in less time than it took to run. So here's my results: 5.14.2: $ time perl -e 'print "aaaaaaaaaaaaaaaaaaaaaaaaaaa" =~ /a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?aaaaaaaaaaaaaaaaaaaaaaaaaaa/ ' 1 real 0m24.227s user 0m24.210s sys 0m0.008s $ time perl -e 'print "aaaaaaaaaaaaaaaaaaaaaaaaaaa" =~ /a{0,27}aaaaaaaaaaaaaaaaaaaaaaaaaaa/ ' 1 real 0m0.007s user 0m0.004s sys 0m0.004s ---------------------------------- 5..8.8: $ time perl -e 'print "aaaaaaaaaaaaaaaaaaaaaaaaaaa" =~ /a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?a?aaaaaaaaaaa aaaaaaaaaaaaaaaa/ ' 1 real 0m30.065s user 0m30.046s sys 0m0.016s $ time perl -e 'print "aaaaaaaaaaaaaaaaaaaaaaaaaaa" =~ /a{0,27}aaaaaaaaaaaaaaaaaaaaaaaaaaa/ ' 1 real 0m0.007s user 0m0.004s sys 0m0.004s --------------------------------

pjscott 14y ago
Real-world examples tend to be subtler, and not quite as easy to explain in an introductory article. Of course you wouldn't really use the for-demonstration-only regex I mentioned. Instead, you would write something reasonable-looking that works just fine unless it encounters a highly unlikely bad input. That's the way I've always seen it happen.
- vampirechicken 14y ago
  In the "real world" I usually try to optimize for the average case, and deal with the "highly unlikely bad input" as a special case. I'm still impressed with the new regex engine, but I have a pathological hatred of contrived examples. It's not you, it's me.

pjscott 14y ago

Real-world examples tend to be subtler, and not quite as easy to explain in an introductory article. Of course you wouldn't really use the for-demonstration-only regex I mentioned. Instead, you would write something reasonable-looking that works just fine unless it encounters a highly unlikely bad input. That's the way I've always seen it happen.

vampirechicken 14y ago
In the "real world" I usually try to optimize for the average case, and deal with the "highly unlikely bad input" as a special case. I'm still impressed with the new regex engine, but I have a pathological hatred of contrived examples. It's not you, it's me.