JSF Performance: How scalable is JSF? [closed]

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I have yet to find a good benchmark on JSF performance. I know what you are thinking, it depends on your code/design/database setup, etc. I know that you have to optimize many things before you need to optimize your presentation layer (for instance you should see how good your database schema is), but let's say for the sake of the argument that we have reached the point in which we must review our presentation layer.

JSF is session-intensive. I've read a bunch of times that this can be a drawback when it comes to writing scalable applications. Having big user sessions in a clustered enviroment can be problematic. Is there any article on this? I'd hate to go to production just to see that开发者_StackOverflow the great JSF lifecycle and CDI integration have a huge cost in performance.

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For high performance, session stickiness must be implemented, regardless of framework or language. How that's done depends on your setup; for example hardware loadbalancers usually have this feature. Then you don't really have to worry about inter-server network latency.

However, JSF+CDI performance on a single machine is also very important. Suppose the overhead is 300ms, that means a 4-core server can only handle 10 requests per second. Not too bad, but not in the high performance class. (Usually not a problem for companies on JEE bandwagons; they are usually enterprise-scaled, not internet-scaled; and they have cash to burn for lots of servers)

I don't really have the performance number though; it would be interesting if someone reports some CDI+JSF stats, for example, how long it takes to handle a typical page with a moderate size form.

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I don't know if there is any truth in the assertion that JSF is heavy on session data. However, I'd have thought that the way to address scalability issues due to large amounts of session data would be to:

• replicate the front-end servers (which you have to do anyway beyond a certain point of scaling), and

• dispatch requests to the front-end based on the session token, so that the session data is likely to already be available in memory.

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The presentation layer is one instance of an -> embarrassingly parallel application. In principle you can scale it by adding hardware; an extreme would be to have one hyper-thread per user in the minute of your site's maximum user-count. So scalablilty is not a problem here. What might be a problem is with pages that have to be rendered sequentially and take a long time to render even in single-user mode: If your JSF takes a minute to render in single-user mode then it will so too in multi-user mode and if you can not render it in multiple pieces in parallel then that is plain-old necessary.