Honestly, now with all the great Scala frameworks, Clojure, and the ability to run Rails, plus Cassandra, Storm, etc, I'm a little creeped out that I'm actually strongly considering building my current new project completely on the JVM.
It is perfectly fine to not squeeze every drop from your hardware and pick Go or Lua. In the same vain, Flask may be x20 slower at a meaningless benchmark but you'd note that the ones that involve actual work, you know, the kind your complex app will actually perform, the more involved it is the more the difference shrinks. All the way down to x4, in other words not an order of magnitutde.
The real takeaway summary should probably be: a well made framework like flask doesn't have so much overhead that the productivity gains it offers are not worth trading a bit of performance for.
A terribly made framework (I won't name names) will bite you in the ass. Choose carefully.
I'll take that any day, over guessing which framework is fastest.
Rails, for example, despite always having been "slow," performs far more than adequately for the vast majority of web applications, scaling patterns are well established, and it's obviously hugely productive for many, many developers and companies.
Facebook and Twitter seem to be doing alright. Care to elaborate?
We have recently released an online market for physical gold trading capable of handling 10k+ concurrent users with horizontally scalable architecture and complex trading engine/accounting logic, and it's all Java. It has to be fast and there is not enough static or almost-static content to make caching effective.
And Java/Scala are disqualified pretty quickly.
I'm currently working on a new project (still research phase) where I was pondering going with Spray and a lightweight Postgresql wrapper because I primarily need to read data from a database, do some transformations on it, and write it out as JSON as fast as possible. I had it working in Spray, but I had issues with server crashes and the speed wasn't as I'd have expected. I fiddled with it for one day, and then, out of frustration, decided to give openresty a try. I've never written much Lua in my life, but after only a couple of hours, I had it working, and it was far, far faster than the Spray implementation. I did some research there, and it seems that the database stuff took a whole lot longer in Scala/Spray than in Lua. Now, of course, I loose type safety, so there may be hidden issues in there, but since I'm really just doing simple data transformations, I think I'm fine with lua / openresty.
As a first verdict, I really, really like what I've seen of Openresty so far.
As a related aside, we have an intention to eventually capture some additional statistics about the implementations such as source lines of code, total number of commits, and possibly lines of code of libraries (where available).
These are just additional data points to use as the reader sees fit, but they may provide some insights. For example: (a) developer efficiency, assuming you are comfortable using sloc as a proxy for developer efficiency, which is admittedly a hotly debated matter; (b) commits are a proxy for the level of attention the particular test implementation has received in our project, since a test with only 1 commit may be unrefined and in need of tuning and a test with dozens of commits may be considered highly volatile; (c) where applicable, the performance impact of additional code, perhaps even as granular as a calculated average per-line cost in rps. The last point might be particularly illuminating for languages such as PHP.
Doesn't look to be "an order of magnitude faster" - 200% faster in some cases - certainly nice numbers, but not a massive game changer for many (yet?).
Sorry, round 7 isn't helping much. Wait for round 8.