Tackling Scalability

Question

I have recently made the shift to a framework called the Yii Framework. Really is good to be working on a framework, solves lot of mundane work. I believe the framework will provide me the platform to build a great site but a senior developer keeps asking me these questions.
How many concurrent users can the site handle?
Is the site scalable?
What is the performance level of the website?
If you were to answer those questions about your project how would you do it?
and also how would you tackle the scalability issues once and for all.

P.S. Any references i could read upon will be greatly welcome.

Answer 1

Scalability is not a hole that one can plug. It is a very broad and generic topic in itself. One of the best approaches I've seen is that of youtube

while (true) 
    identify_and_fix_bottlenecks();
    drink();
    sleep();
    notice_new_bottleneck();

Having said that, database is usually the bottleneck in most of the web applications and the choice of web framework doesn't matter much. Things like number of concurrent users and performance levels will be sufficiently large for most of the frameworks.

While this answer is quite late, I hope it helps you in your future projects.

Answer 2

You should not look at scalability as a bandaid or a one time fix.

As the usage of your application changes, your scalability requirements will change and evolve. Also, there is no silver bullet for addressing scalability. It is a mix of various approaches like caching, replication, distribution, performance tuning, hardware upgrades etc. You should choose from those based on the context of "what you want to scale" and where will you get maximum bang for the buck!

check out this link http://sevenoct.wordpress.com/2013/07/04/scaling-applications/

which has some good information about scalability and how not to fall into traps of "sought after" scalability mantras