With the overhead of threading, isn't the triumph of a transducer (no seq allocations) rather subtle in the case of pmap?
At any rate!, as a point of interest, since you mentioned a quirk of pmap's thread usage: It apparently has to do with whether the input sequence is a chunked sequence or not. Comparing two possible inputs user> (def c (into [] (range 50))) ;; chunked user> (def n (into '() (range 50))) ;; not chunked With pmap invoking a function that just returns the thread's name (and takes some time, so as to keep its assigned thread busy enough not to accept more tasks right away) user> (defn f [x] (Thread/sleep 22) (.getName (Thread/currentThread))) #'user/f user> (count (distinct (pmap f c))) 32 user> (count (distinct (pmap f n))) 7 The test is not perfect because it does not show that all 32 threads were used *at once*. There were simply 32 distinct threads used at one point or another. Nonetheless the difference between 7 and 32 is suggestive. In this environment there are 4 "processors", so 32 is indeed more than you might want. The docstring about pmap could be clearer about this. -- 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 --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
