On Tuesday, October 11, 2011 3:55:09 AM UTC+2, Lee wrote: > > > Does your pmap-pool permit nesting? (That is, does it permit passing > pmap-pool a function which itself calls pmap-pool?). If so then that would > be a reason to prefer it over my pmapall. > I expect it would be possible to nest it (possible as in "no exceptions or deadlocks"), but I can't see any scenario where you would want to - you would get an exponentially increasing number of threads. If 48 cores each start 48 threads, each of those threads start another 48 etc., it doesn't take long before you have enough threads to bog down even the most powerful server.
But what would be the purpose of a nested "run this on all cores" construct? You are already running on all cores, there are no spare resources, so in terms of CPU time I can't see how it would differ from merely having the pmapped function use a plain same-thread map? There are no particular advantages to pmap-pool over pmapall that I can see, except that pmap-pool lets you control the number of threads more easily. (E.g. for debugging "where does it stop scaling linearly" problems.) I thought creating thousands of agents (as pmapall does) would be more expensive, so I tried an alternative, but in practice they seem to be equally fast; at least on this test and the kind of hardware I have access to. So pmapall wins by having fewer lines of code. jf -- 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
