Metrics Per Queue/Flow-Control/Url etc..

Metrics per Queue/Flow-Control/Url are requested time to time but not implemented since they are basically expensive.

They are expensive because number of queues/flow-controls/url's can grow big.

One option is to let people configure a limited amount and keep statistics only for them.

Opened a generic issue but it would be great to get feedback on specific needs and use-cases in the comments.