This isn't really a comment on Java, Ruby, Twitter, Google, or my programming ability. It's a comment about the fact that once you've designed a scalable distributed system, the constant factor runtime isn't so important.

Twitter has clearly engineered a working distributed system (or you would have read stories like "5% of Twitter users lost their tweets when our servers caught on fire last night"), so the fact that they wrote it in Scala or Java is largely irrelevant. They need fewer computers than they would have if they wrote it in Ruby again, and that's not something to discount, but I think it's technically possible to have a full Ruby stack do what Twitter does. And, they would have needed even fewer computers if they used C or C++. So it's clear that Java was a social choice (it had the right books, libraries, and stack of resumes) rather than an absolute must.

Besides, Ruby and Java both make the same C library calls to do I/O. So it all ends up being the same for everything except search, trending tweets, and other cpu-intensive analysis.

You're right and I know that "appeal to authority" is not a valid argument mechanism.

With that in mind, I just couldn't pass up the opportunity to make an amusing comment.