I'm trying to track down the reason that I sometimes see a lot of concurrency in my system (up to 1200% CPU utilization on a dual quadcore mac that also has some kind of hyperthreading, allegedly allowing a maximum of 1600% CPU) while other times it gets stuck at around 100-200%. My system (a genetic programming system) has a *lot* of randomness in it, so it's hard to repeat runs and get a firm handle on what's going on.
But after a bunch of testing I'm beginning to suspect that it might be the random number generator itself (clojure-core/rand-int in this case, which calls (. Math (random))). This seems at least somewhat plausible to me because I guess that the underlying Java random method must be accessing and updating a random number generator state, and so this would be a concurrency bottleneck. So if I'm in a condition in which lots of concurrent threads are all calling rand-int a lot then all of the accesses to the state have to be serialized and my concurrency suffers (a lot). Does this sound plausible to you? If so, is there a straightforward way to avoid it? It is not important to me that the random numbers being generated in different threads be generated from the same generator or coordinated/seeded in any way. I just need lots of numbers that are "random enough." I guess I could roll my own random number generator(s) and either have a lot of them with independent states or maybe even make them stateless (always generating numbers by scrambling the clock?). But I would hope there would be something simpler. Thanks, -Lee -- Lee Spector, Professor of Computer Science School of Cognitive Science, Hampshire College 893 West Street, Amherst, MA 01002-3359 lspec...@hampshire.edu, http://hampshire.edu/lspector/ Phone: 413-559-5352, Fax: 413-559-5438 Check out Genetic Programming and Evolvable Machines: http://www.springer.com/10710 - http://gpemjournal.blogspot.com/ -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en To unsubscribe from this group, send email to clojure+unsubscribegooglegroups.com or reply to this email with the words "REMOVE ME" as the subject.
