Ok, hope it works out. > On Sep 23, 2017, at 8:03 PM, lawrence.krub...@gmail.com wrote: > > > Thanks for the answer. I am surprised because I used this code for years > without ever seeing that error. I'm trying to imagine what I did differently > this one time. I've added error detection, we'll see if it happens again. > > > >> On Friday, September 22, 2017 at 7:34:49 PM UTC-4, Neil Okamoto wrote: >> >> 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 a topic in the Google > Groups "Clojure" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/clojure/isBN8-E59qo/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > clojure+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout.
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