[ericmoritz]

Yeah, because of cowboy and Erlang's design it is going to out perform a single process evented server hands-down.

  1. The evented servers are bound to one CPU, Erlang will use all CPUs 
  2. any bit of blocking code will stall the other code, even it just for a moment.

It is a little unfair to compare the two approaches.

[rdtsc]

I am not sure it will always under-perform with one CPU. It depends if async threads are used and if kernel poll is enabled. Erlang is designed for better low latency response at the expense of _some_ sequential slow down. I wonder if Erlang would scale slower but it will throw less errors as number of requests increases.

EDIT:

Also it would seem benchmarking Erlang and forcing it to run on a single core just like node.js is deliberately handicapping it. One of the strengths of Erlang is exactly the ability to take advantage of multiple cores.