HttpServerConnection: No messages for Http connection have been received in the last 10 seconds [API (REST) requests accumulates Icinga2 threads]

I have a couple of Dashing Dashboard Ruby scripts that perform REST requests to Icinga2.
All of this works as expected, however, Icinga2 quickly accumulates threads in this fashion. It looks like Icinga2 doesn't kill the threads after it has finished.

I must, as a workaround, reload Icinga2 every X minutes, because otherwise it will have so many threads the whole operating system gets in trouble and cannot fork or create any other process until Icinga2 is restarted.

This problem can already be noticed with the Default Dashing Dashboard Jobs. Not a single Thread gets killed, ever.

Edit:

in /var/log/icinga2/icinga2.log, I see many, many lines like this:



Why doesn't Icinga2 close these http connections when obviously no more communication is happening?

Or, my actual question would be: What kind of REST-post do I need to send in order for Icinga2 to close the connection and thus also the thread?

Thanks for any help!