At SendGrid, much of our stack is Go but started off as Perl and Python. Our incoming clusters are geographically distributed to reduce latency, but a handful o

At SendGrid, much of our stack is Go but started off as Perl and Python. Our incoming clusters are geographically distributed to reduce latency, but a handful of nodes do just fine processing 40k rps. We could dramatically reduce cluster size, but choose not to for reasons around availability. These incoming requests generally create four to eight logging events that are processed and emitted for stats, tracking, and/or published to customer webhooks. Additionally, our MTA is now in Go, and each incoming request usually has some multiplier for the number of recipients. We typically expect around a 20x improvement in throughput when we rewrite a service. Granted this depends on the nature of the service. As much as reduced server costs and greater performance are awesome, one of my favorite parts is the increased maintainability of the services. Perl's AnyEvent and Python's Twisted (aptly named, btw) were much harder to reason about. Go's concurrency and simplicity make it a win for us.