Maybe it's because you attempted method invocation via reflection but the object is nil. So for example if (threads) returns a list containing nils, then calling (.getId t) or (.getName t) would probably throw a null pointer exception. I'm not sure it's possible for (ManagementFactory/getThreadMXBean) to return nil, but if it does then (.getThreadCpuTime mgr ...) would similarly fail.
So best guess is, take a look at the implementation of "threads". On Friday, September 22, 2017 at 1:37:04 PM UTC-7, lawrence...@gmail.com wrote: > > I've been using this code for years. I copy and pasted it from someone > else on this group, someone much smarter than I am. I have never seen an > error from this code. Now suddenly I get a null pointer exception at the > last line of this code: > > (ns denormalize_mysql_to_mongodb.monitoring > (:import > java.lang.management.ManagementFactory) > (:require [clojure.string :as st])) > > > (defn thread-top > "Return a seq of threads sorted by their total userland CPU usage." > [] > (let [mgr (ManagementFactory/getThreadMXBean) > cpu-times (map (fn [t] > [(.getThreadCpuTime mgr (.getId t)) t]) > (threads))] > (map > (fn [[cpu t]] [cpu (.getName t) (.getId t) t]) > (reverse (sort-by first cpu-times))))) > > This error is thrown at startup. I don't know much about ThreadMXBean. Can > anyone give me a clue why any of this would be nil? > > > > > > -- 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.
