FastCGI C++ vs. A Script Language (PHP/Python/Perl)

scripting languages may be slower than C, but is this a problem? almost never. and if the performance becomes a problem, you start to translate only the critical parts.

twitter/ruby is a good example; ruby is slow. some of the language features (that make ruby nice in the first place) just prevent different kinds of optimization (there is a great article by the jruby guy about this ... was it ola bini? can't remember).

still, twitter is powered by ruby, because ruby is fast enough. not long ago, "the blogs" reported twitter migrating to scala for performance reasons ... the truth was, only the messaging queue (and other parts of the backend) moved to scala. yahoo runs on a mixture of languages; php for the frontend, other, faster languages are used where performance is critical.

so, why is performance not that important? there are several reasons:

• database bottleneck: not the scripting is slow, the database is
• clientside bottleneck: rendering in the browser takes longer than the request. optimize the server side, and nobody will notice
• horizontal scaling: often it's cheaper to add another server and thus triple the requests/sec than to optimize the app
• developer time and maintenance are the most expensive parts of your project. you'll get more cheap python devs that maintain your app than web-enabled c-coders in less time
• no compiling, short dev cycles

another pro-scripting point: many of the scripting languages support inlining or inclusion of fast (C) code:

• python, inline c
• php: extensions in c
• server-side javascript via rhino: direct access to java/jvm (a good example for this is orf.at, one of the biggest websites in austria, powered by helma - serverside jvm-interpreted javascript!)

i think, especially in web developement the pros of high-level scripting far outweight the cons.

Several years ago, I more or less learned web app programming on the job. C was the main language I knew, so I wrote the (fairly large-scale) web app in C. Bad mistake. C's string handling and memory management is tedious, and together with my lack of experience in web apps, it quickly became a hard-to-maintain project.

C++ would be significantly better, mainly because std::string is much nicer than char*.

However, now I'd use Python every time (though PHP is not a terrible choice, and perhaps easier to get started with). Python's string handling is awesome, and it handles Unicode seamlessly. Python has much better web tools and frameworks than C++, and its regex handling and standard libraries (urllib, email, etc) work very well. And you don't have to worry about memory management.

I'd probably only use C or C++ for a web app if I was severely RAM-constrained (like on an embedded micro) or if I worked at Google and was coding a search engine that was going to have to respond to thousands of queries per second.

Using C++ is likely to result in a radically faster application than PHP, Perl or Python and somewhat faster than C# or Java - unless it spends most of its time waiting for the DB, in which case there won't be a difference. This is actually the most common case.

On the other hand, due to the reasons benhoyt mentioned, developing a web app in C++ will take longer and will be harder to maintain. Furthermore, it's far more likely to contain serious security holes (nowadys everyone worries most about SQL injection and XSS - but if they were writing their webapps in C++ it would be buffer overflows and it would be their entire networks getting p0wned rather than just the data).

And that's why almost nobody writes web apps in C++ these days.