Johannes Schindelin wrote: > Actually, that's funny. Yesterday, I repeated my claim that pcre is > slow on IRC, and Sam Villain on IRC accused me of trolling. But as you can > see from my postings on this list ($gmane/41682), you can see that _I_ had > numbers to back up my claim. > > So no, I think pcre is just not worth it. > A strange thing to conclude from your figures, which show pcre as the fastest out of several libraries that you tested. Your figures show exactly what I was saying on IRC - that a DFA (external grep) vs NFA engine (most regex libraries) is inherently faster. The paper I linked to, specially selected as I had previously read a significant amount of the peer review the paper received, explained this in detail. The one piece of feedback your numbers got on-list also mentioned this. However there is a further flaw in your study. All but one of the performance tests use an external program, which on a given system may or may not be faster because of pipeline performance characteristics. You could improve the quality of the result by using the 'pcregrep' program as a data point. It might also be worth trying a few more complex patterns. I suggest reading the paper (http://swtch.com/~rsc/regexp/regexp1.html) for some background before repeating the experiment. Apologies for not reviewing your numbers at the time; it sure is hard to keep on top of this list. But very interesting that they seem to suggest pcre would be the best choice from a performance perspective, even though the figures are very preliminary. Perhaps it is worth pursuing after all. Sam. - To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
