If you have this: user> (def f (future (Thread/sleep 20000) :done)) #'user/f user> @f ; this immediate deref blocks for 20 sec, finally returning :block :done user> @f ; returns immediately :done
What is actually happening when you call the first @f? You are waiting for the function to finish executing and return a value? Or are you waiting for a return value to appear in the ref slot? Is there any way to check if there is a value ready or if the function has returned w/out blocking? On Thu, Nov 26, 2009 at 12:32 AM, Hong Jiang <h...@hjiang.net> wrote: > Thanks. Yeah, after adding a call to shutdown-agents, the process no > longer hangs. > > On Nov 25, 1:15 pm, Kevin Downey <redc...@gmail.com> wrote: >> future also uses the same threadpool as agents, so once you call >> future the threadpool spins up, and just sort of sits around for a >> while before the jvm decides to exit, which is why the program would >> sit around for 50 seconds >> >> >> >> On Wed, Nov 25, 2009 at 10:30 AM, Hong Jiang <h...@hjiang.net> wrote: >> > Thanks for your replies David and Sean. Yes, I made a mistake thinking >> > that future takes a function and its arguments, so the function was >> > never called in my program. >> >> > On Nov 25, 8:21 am, David Brown <cloj...@davidb.org> wrote: >> >> On Tue, Nov 24, 2009 at 09:04:38PM -0800, Hong Jiang wrote: >> >> >Hi all, >> >> >> >I'm new to Clojure and playing with small programs. Today I wrote a >> >> >snippet to figure out how future works: >> >> >> >(defn testf [] >> >> > (let [f (future #(do >> >> > (Thread/sleep 5000) >> >> > %) >> >> > 5) >> >> > g 7] >> >> > (+ g @f))) >> >> >> You don't ever evaluate the function containing the sleep, you just >> >> create it, and then immediately return 5. >> >> >> Future contains an explicit do, so you can just do the steps in the >> >> future: >> >> >> [f (future >> >> (Thread/sleep 5000) >> >> 5) >> >> ... >> >> >> Or, if you want to get the function call in, you'll need to call it: >> >> >> [f (future (#(do (Thread/sleep 5000) %) 5)) ...] >> >> >> David >> >> > -- >> > 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 >> >> -- >> And what is good, Phaedrus, >> And what is not good— >> Need we ask anyone to tell us these things? > > -- > 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 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
