UDP input queue monitoring

Hello guys, I was wondering if anyone knows how to monitor UDP input plugin queue? My config is:

input {
    udp {
        codec => elog {
            elog_definitions => "XXX"
        }
        port => XXX
        queue_size => 200000
        receive_buffer_bytes => 24777216
        workers => 8
    }
}

As you can see its set to 200 000 but is there any way to see if its full or not? Queue type is memory.

Do you think in keep a log as mode debug and count input vs output??

I was hoping for some already defined metric like counting events because this seems like something pretty basic to keep an eye on. Maybe some configuration is needed?