To be able to limit CPU consumption of Blazegraph (T206108), we need to better understand the factors involved. Query and / or request concurrency might be a good indicator of resource consumption.
Possible ways to measure it:
1. Instrument Jetty to publish this metric over JMX, consumed by the current Prometheus JMX exporter
2. Instrument Blazegraph (via a custom Servlet filter, or via [[ https://metrics.dropwizard.io/4.0.0/manual/servlet.html | Dropwizard Metrics ]]) to publish HTTP request concurrency over JMX, consumed by the current Prometheus JMX exporter
3. Publish the metric from Nginx via [[ http://nginx.org/en/docs/http/ngx_http_stub_status_module.html#stub_status | stub_status ]] and [[ https://github.com/nginxinc/nginx-prometheus-exporter | nginx-prometheus-exporter ]]
4. Collect metric already exposed by blazegraph, adding them to our `prometheus-blazegraph-exporter`