--- Steffen Schwigon <[EMAIL PROTECTED]> wrote: > Now I'm not sure about its performance. I expect about 1 to 3 > requests > per second at peak times and I don't know yet how long my prolog > programm will take. > > Does Language::Prolog::Yaswi start a new "pl" process for every > query? > The README talks about threads, so maybe it already does something > clever about this.
The reason threads are mentioned is because Perl and SWI-Prolog must both have threads enabled or both NOT have threads enabled. Threads are not a requirement. I'm not aware that SWI-Prolog does start another process but I certainly wouldn't place a bet on that. I would strongly recommend Devel::Profiler or something similar on your code to find out where your true bottlenecks are. If you do find out your Prolog calls are slow, then you can spend the time tuning those queries (of course, if it's just too many Prolog queries in too short of a time, tuning might not help). On the other hand, if profiling can get you significant gains in the Perl portion, then you may get a win just by tuning Perl. If you can't speed up the Prolog, trying to replicate it's functionality in Perl may be difficult. Of course, there are tricks you can use to push much of the logic into a database and making multiple calls from Perl. That's probably slower but a good RDBMS has optimizations that Prolog often doesn't so it's worth exploring if you're stuck. If you really have problems with Prolog, I would suggest issuing a bunch of short Prolog queries and timing them and then issue some long-running queries. Time them both from Perl and directly in SWI-Prolog as if you were running it there. That can give you some idea as to the performance impact from Perl. Cheers, Ovid -- If this message is a response to a question on a mailing list, please send follow up questions to the list. Web Programming with Perl -- http://users.easystreet.com/ovid/cgi_course/
