The laziness of map is irrelevant here, because .invokeAll is treating it as a collection and realizing it all immediately. Your version with for is just as lazy. What's actually changed is that your map and for produce entirely different outputs: the version with map calls test-fn, and the version with for produces a function which, when invoked, will call test-fn. Since the latter is what the original code you copied from does, of course only that version works. You could change your map to (map #(fn [] (test-fn % 1 5)) deliveries) as an easy fix, though personally I wouldn't use the #() syntax here; its closeness to a (fn) form is a little confusing. (map (fn [i] (fn [] (test-fn i 1 5))) deliveries) is equivalent, of course. Personally I prefer the version with the for-comprehension.
On Friday, June 14, 2013 2:30:04 AM UTC-7, Amir Wasim wrote: > > I was using the first example to make a process executing parallely > > > (defn test-stm [nitems nthreads niters] > (let [refs (map ref (repeat nitems 0)) > pool (Executors/newFixedThreadPool nthreads) > tasks (map (fn [t] > (fn [] > (dotimes [n niters] > (dosync > (doseq [r refs] > (alter r + 1 t)))))) > (range nthreads))] > (doseq [future (.invokeAll pool tasks)] > (.get future)) > (.shutdown pool) > (map deref refs))) > > > > i was generating taks just like above as follows > > tasks (map #(test-fn % 1 5) deliveries) > > But only one task was active at a time, although Executors was configured > with 4 threads. It occurred to me that map itself is lazy and it is > realized in doseq one at a time. A possible fix is to use for instead of > map to generate tasks > > I tried with the following > > tasks (for [delivery_ deliveries] #(test-fn delivery_ 1 5)) > > and it works and 4 threads are active during execution. > > > > -- -- 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/groups/opt_out.
