Building a web backend with C++ is a very dangerous and complex ordeal, you're extremely likely to expose memory based vulnerabilities to the entire world.
Google, Facebook, Amazon and Twitter beg to differ (not completely C++, but for services where it makes sense). Also nginx, passenger and other parts of your Ruby app.
Shrug, you have no idea what you are talking about [1]. Also nginx and passenger are webservers and claiming they are not part of your web app is a pretty wild claim when they literally send http responses to browsers (unlike memcached).
I think you're the one who got confused with the context here.
We're talking about web-app, not microservices.
We're talking about CRUD with DB migration, sessions, caching, etc.
I recalled Google's dl.google.com was implemented in C++ and Brad F rewrote it with Golang. We're not talking about microservice that serves file here. We're talking about the main web application that serves wikipedia, youtube original version (they might had revamped it sometime post acquisition with web gateway and bajillion microservices), Google Search (was Java servlet), Facebook original web-app (was PHP, became HVVM/H4CK.
So yes, I _know_ what I'm talking about in terms of the context of a web-application here. Do you?
RoR and whatever C++ based web backend there is count as a valid comparison in my book. But comparing the languages itself is maybe a bit off.
On a side note, you can actually compare their performance here if you’re really curious. But take it with a grain of salt since these are synthetic benchmarks.