You do nothing for the while loop to end
(while true
... <do nothing>))
This will still eat cpu time (a lot if there's no "pause" inside, empty
chan/takes inside or not.
That's why usually you use loop/recur with a condition of the take!
result or put! result in case of push.
(go-loop []
(when-let [x (<! ch)]
(do something with x)
(recur))))
On Monday, January 23, 2017 at 10:19:00 AM UTC+1, Torsten Uhlmann wrote:
>
> I'm experiencing this weird behavior in my app- when restarting the
> components of my app some have a core.async channel and a go-loop inside.
>
> When trying to close! these channels the cpu usage of my app goes way up,
> and stays up- as if the loop does some polling.
>
> I prepared a minimal example here:
> https://github.com/tuhlmann/async-close-problem
>
> The problem occurs only if the channel has a go-loop or a "while true"
> loop inside, otherwise closing the channel works fine.
>
> I experience the problem on both Windows and Unix.
>
> To reproduce:
>
> git clone https://github.com/tuhlmann/async-close-problem
>
> cd async-close-problem
> lein repl
> ;; open a top or process view in another terminal
>
> (start-chan)
> ;; confirm used cpu for the Java process is very low
>
> (stop-chan)
> ;; watch used cpu go way up
>
>
> The go block is very simple:
>
> (a/go
> (while true
> (when-let [document (a/<! channel)]
> (println "New document to render: " (pr-str document)))))
>
> "channel" is the one I close with (a/close! channel)
>
> In this example I do not send anything into the channel, just starting it
> up and closing it down.
>
> Am I doing something wrong?
>
> Thanks,
> Torsten.
>
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