I think that even if the stable dotnet runtime metrics for thread pools currently have a different approach, we should attempt to prefer the dotted namespace naming strategy, both for the thread pools and the tomcat request processor (but I agree that it might be a matter of taste here).

While the tomcat "request processor", I still think it belongs to the tomcat.request.* namespace, so I would lean towards using tomcat.request.processor.name instead, also this would make the tomcat.request.* metrics share a common namespace prefix as the their metric attributes. Also, we already have a similar pattern with the jvm.memory.used metric where the attributes are jvm.memory.type and jvm.memory.pool.name.