OpenStack consists of multiple projects. Each project, in turn, is composed of multiple services. To process some request, e.g. to boot a virtual machine, OpenStack uses multiple services from different projects. In the case something works too slowly, it's extremely complicated to understand what exactly goes wrong and to locate the bottleneck.

To resolve this issue, we introduce a tiny but powerful library, osprofiler, that is going to be used by all OpenStack projects and their python clients. To be able to generate 1 trace per request, that goes through all involved services, and builds a tree of calls (see an example http://boris-42.github.io/ngk.html).

For more details take a look at:
https://github.com/stackforge/osprofiler