Hacker News Reader

What this says to me, a non-RoR user, is that it's harder to build websites with Java than with RoR, but if you pass a certain (very unusual) level of traffic, you'll wish you'd made the extra effort; otherwise, you'll be glad you didn't. (Extra effort isn't free.)

If you get to the scale of twitter, and more importantly if you have written a real time messaging server with a web application framework, it doesn't matter which framework or language you started with as you're going to be completely rewriting your entire stack at some stage as different parts fail in order to deal with the load (unless you have an incredibly experienced team who has written a twitter equivalent before and scaled it to 15000 messages a second). There's no difference between ruby or python (or perl, or php) in that regard - they are all interpreted and relatively slow, which starts to matter at this scale. And also even if you had used java or c in the fist place, if you had an architecture not written with massive scale in mind, you probably wouldn't survive that growth without radical changes on every level of your stack.

Re ruby versus python, the popularity of rails is partly historical accident, partly that ruby is a nice language which doesn't get in the way and is ideally suited to this domain, and partly that rails is deals with lots of the basics of web development for you without getting in the way too much when you need to adapt it. None of that means ruby is better than python, but I'd disagree that people put up with ruby in order to use rails - it's a really nice language in its own right, but it is not highly performant (though it is getting better). For most websites of course, many of which can employ caching, that is a non-issue, even at large scale - witness the success of Wordpress in php which would not survive even modest loads without caching.

python is not interpreted,it is compiled in bytecode just like java.

But the bytecode is then interpreted.

> python is not interpreted,it is compiled in bytecode just like java.

Depending on the implementation, so is Ruby. The canonical MRI 1.9 compiles to bytecode and interprets it. But unlike python, it doesn't write the bytecode to disk. The loading of bytecodes has been disabled until a bytecode verifier is implemented.

Yes sorry that was an over-simplification due to ignorance - Ruby 1.9.3 and Python are both compiled to bytecode now, but still tend not to do as well in speed comparisons to the Java VM (which perhaps has just had more effort on optimisation). So in that sense it is like Java, but slower - for most people that really doesn't matter, but for twitter with this level of traffic, it probably would. You can of course run Ruby on the JVM now too, but I think that came too late for twitter.

What I found interesting from another twitter blog post linked from the article was that they are actually running on a modified version of Ruby 1.8.7 REE, not Ruby 1.9.x as you might expect, so that must really skew their comparisons![1] Anyway, there are a lot of variables in a huge system like twitter, so boiling it down to just a problem with Ruby performance seems pretty simplistic (as you'd expect from the register), and I seriously doubt they could have avoided this kind of rewrite and refactor of their entire stack in any language when hitting this sort of scale. To me it doesn't say much at all about Ruby as a language or whether it is suitable for websites.

[1] http://engineering.twitter.com/2011/03/building-faster-ruby-...

Yup, and from experience, you're going to end up rewriting big chunks of your stack multiple times. (In a previous life, I worked on a team that grew a Java-based SMS gateway from an initial design limit of 10 msg/s on a single box to 10,000+ msg/s sustained, replicated across a high-availability cluster.) Props to the Twitter team for pulling it off, because at volumes like that you start to get into seriously arcane stuff like JVM garbage collection tweaking, or otherwise a full GC that halts all threads of execution for 30+ seconds will create entire pods of fail whales.

http://www.oracle.com/technetwork/java/javase/gc-tuning-6-14...

Python has a roughly equivalent MVC web framework called Django.

Ruby and Python as languages are not radically different in kind, but their respective developer communities have had different focuses, and as a consequence the library of tools are not identical.

Ruby on Rails became popular because people were dissatisfied with the way that web development was being done, and DHH is very good at marketing/propaganda. Ruby on Rails has had a substantive effect on the way that web development is done, and there have been numerous attempts in other languages (that didn't already have a framework like Django) to recreate the things that Ruby programmers enjoy with Rails (CakePHP and Grails come to mind immediately).

This is spot on.

To elaborate a bit, Rails tended to have a lot more generated code (the fabled "magic") that really sped up development of your standard CRUD apps. As far as I can tell, this was fairly novel in web development. Django didn't really have a focus on that, you spent a little (lot?) more time configuring. It's better now though.

Of course, at the complete opposite of the spectrum, you have very minimalist stuff like Flask (Python) or Sinatra (Ruby) which is doesn't include a lot of bells and whistles. You'll have to import your own ORM, templating, etc...

Ruby has nothing to do with Python. Python is strongely typed and compiled into bytecode, just like java. It is just not the bloated and verbose language java is , which allows fast and pragmatic development.

> Python is strongely typed

Like Ruby.

> and compiled into bytecode

Like JRuby.

Python and Ruby are comparable languages. They are both high-level dynamic languages, with the same sort of tradeoffs (eg, you can do more with less characters than in most statically typed languages, at the expense of safety and performance). There are however significant differences in terms of philosophy, ecosystem and community between the two.

Except you dont need a JVM to get performances in python. Using a JVM destroys any perspective of cheap and easy deveployement. If i have to use a JVM , i'd certainly not use JRuby when i can get scala.

> Except you dont need a JVM to get performances in python.

Python's performance is only slightly ahead of Ruby's. Both Python and Ruby are a bad match for CPU intensive tasks(provided we are talking pure python/ruby and not native extensions). Network and IO in general is salvaged by using evented io(or some high level evented framework).

Exactly. You have the same sort of solutions for squeezing additional performance out of Python and Ruby: - using evented framework (network/IO bottleneck) - using native code (CPU bottleneck) - using a different implementation (Python has an edge here with PyPy, as long as your dependencies run on it)

Because numerical processing is a major use case, Python has a number of techniques to easily speed up critical sections of code (numpy, cython, pypy).

I am not aware of comparable features in Ruby.

Numpy is a dedicated library where the critical code is in C, but that's a library, hardly a language feature. I don't know if there is any numerical processing library in Ruby.

Cython is not intrinsic to Python either. I see there is a ruby2c gem, but I have no idea how it compares to Cython.

As for pypy, that's about switching to a different runtime, the same way Ruby people would go to JRuby.

None of this turns Ruby into apples and Python into oranges, I'm afraid.

> Using a JVM destroys any perspective of cheap and easy deveployement.

I doubt that. The fact that jruby is close to bug-by-bug compatibility means that for most projects you can go and develop on mri or rubinius for fast development and use jenkins/travis/... to run your testsuite against jruby. You can then do integration tests as well as staging on jruby to catch anything your testsuite didn't catch. I've seen more than one large project take that course of action and do just fine.

Deployment on jruby isn't any harder than deployment on any other ruby. It's still "puma start" or whichever server you chose. You can however package your app in a war use a standard servlet container such as tomcat or jetty to deploy, but that's strictly optional.

I deploy SpringMVC apps, using an embedded Jetty instance into much the same environments as I do Python apps based on Tornado or Twisted.

The biggest win for me is dependency management. One my maven file is setup right, I only need a JRE on the host.. Dependency management is a bit trickier with Python, perhaps for Ruby as well.

As far as I know, Ruby has proper support for higher-order functions and lexical closures (aka code blocks).

http://stackoverflow.com/questions/4769004/learning-python-f...

I'll throw out another factor:

When Rails was introduced, there were no other substantive Ruby web frameworks - Ruby itself was relatively obscure compared to every other web-capable tech. As such, it (Rails) had no competition in the framework space. PHP, Java, Python and other languages all had competing web frameworks to choose from.

> but if you pass a certain (very unusual) level of traffic, you'll wish you'd made the extra effort

I'm not sure that's the case. Perhaps had they started out by trying to scale to their current levels they would never have gotten off the ground. When you start developing a system for a new company your largest obstacle is almost always lack of product/market fit.

Isn't there some famous quote about premature optimisation? :-)

> What this says to me, a non-RoR user, is that it's harder to build websites with Java than with RoR, but if you pass a certain (very unusual) level of traffic, you'll wish you'd made the extra effort; otherwise, you'll be glad you didn't. (Extra effort isn't free.)

Twitter hasn't phased out Rails, it has replaced background services written in Ruby.

> Fine, but what I wish I understood was why RoR is so popular to begin with.

That is hard to explain. You will have to try it out yourself and compare with whatever you are currently using.

> why isn't one of them Python on Rails

As other responses pointed out, Python has Django. And no, Django isn't rails inspired. Django was developed independently. Also, the languages and philosophies differ significantly to have a Python on Rails.

It's called Play! Framework on the Java/Scala land. You got the benefits of both, ease of development and performance/scalability.

also dont forget grails!

and you can use Play from clojure too, if you think you are pragmatic enough...

Python's culture heavily encourages explicit, consistent code while Ruby's culture is a lot more flexible in that respect. Rails makes many assumptions by default and has an API that is based on clever coding for the sake of maximizing productivity. That stuff would likely not fly in the Python community.

There are some of us Ruby users that find the Rails approach absolutely disgusting... I don't believe it maximize productivity either - the moment you need to deviate too much from the defaults you quickly descend into hell, trying to figure out what "magic" is happening behind your back.

You're making it sound like Ruby is a terrible language that's either much worse than Python or completely redundant with it. I simply don't think that's the case.

Maybe it's hard to build something like rails and get the details right? It's like asking why PC makers don't do a better job at copying apple.

Its called Django.