Sure, but is it unreasonable to wonder why they need such an architecture? LinkedIn is basically a CRUD app, and while they have a wall now and yadda yadda, I wonder how much of this rearch was really necessary, over simple refactorings and sysadmin attention to the nuts and bolts.
Ability to stream stuff from an Event driven reactor loop makes lot of sense when it comes to raw performance actually.
If you throw in Postgres database in mix which supports asynchronous queries - one can pretty much beat 20 passenger instances serving similar request. The problem again though is, doing non-blocking IO does not reduce database load. So, if likely they re-architected that bit as well.
