MZBench is open-source benchmarking tool written in Erlang. It allocates nodes directly in EC2 and setups Erlang cluster. System has web-frontend for charts and other useful information during the benchmarking. It is used for 100-node clusters and millions messages per second rates.

In this talk I want to show how functional programming helped us to build this system. The absence of implicit state makes possible to distribute working processes across a cluster. Like in other functional languages it is easy to create a DSL inside Erlang, so you could have a subsystem with a different semantics and different meaning.

I would also show how Erlang helps with immediate environment updates and harms with full-mesh network topology.