This error is also intermittent. It doesn't happen every time I start the
app. I would guess this is some kind of timing issue, but I can't think
where the issue of timing comes up.
On Monday, January 25, 2016 at 4:04:50 PM UTC-5, piast...@gmail.com wrote:
>
> I've never had this problem before, but now I'm getting this:
>
> in resource-usage there was this exception: #<NullPointerException
> java.lang.NullPointerException>
>
> at startup, for this function:
>
> (defn- resource-usage []
> (let [my-pool (at/mk-pool)]
> (at/every 60000
> (fn []
> (try
> (timbre/log :trace "Resource usage: "
>
> (monitoring/show-stats-regarding-resources-used-by-this-app))
> (doseq [x (monitoring/thread-top)]
> (timbre/log :trace x))
> (catch Exception e (println "in resource-usage there was
> this exception: " e))))
> my-pool)))
>
>
> This line:
>
> (timbre/log :trace "Resource usage: "
>
> (monitoring/show-stats-regarding-resources-used-by-this-app))
>
> Correctly gives me:
>
> Resource usage: Memory in use (percentage/used/max-heap): ("9%" "43M"
> "444M")
>
> So the problem comes here:
>
> (doseq [x (monitoring/thread-top)]
> (timbre/log :trace x))
>
> Which relies on java.lang.management.ManagementFactory
>
> (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)))))
>
>
> With some code borrowed from here:
>
> http://lifeisagraph.com/2011/04/24/debugging-clojure.html
>
> Does anyone see a place where a NullPointerException might get started?
>
> I assume this must be some circumstance unique to startup. I don't think
> this problem repeats.
>
>
>
>
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