Our application is structured in a somewhat unusual way in that each of our customers had a dedicated pool of processes running our application (the same application just pointed to different database entries). This means that is not untypical for our servers to have several hundred rails applications running. We are currently using Passenger on top of apache to server out the web app.
My concern is about the additional overhead that I should expect on the server for adding the New Relic agent. Specifically, the number of additional file descriptors (as per actual files and network sockets) per running rails process and ram overhead? Does the New Relic Agent do any pooling of it’s own? If so, does this pooling only work within a particular application pool, or across all applications on the server?