[nathanmarz]

By your logic, all testing is invalid except for usage by real users. Two things:

- We stress-tested the hell out of our implementation well beyond Twitter-scale, including while inducing chaos (e.g. random worker kills, network partitions). - We ran it for real when we launched with 100M bots posting 3,500 times / second at 403 average fanout. It worked flawlessly with a very snappy UX.

The second-system effect is a real thing, but there's a difference when you're building on radically better tooling. All the complexity that Twitter had to deal with that led to so much code (e.g. needing to make multiple specialized datastores from scratch) just didn't exist in our implementation.

[yowlingcat]

> By your logic, all testing is invalid except for usage by real users

That is exactly correct. All testing is make believe except for real case studies by real customers with an intent to pay, and barring that, real pilots with real utilization. Otherwise, you run the risk of building a product for a version of yourself that you are pretending is other people.