Question

I’m working on a web application framework, which uses MSSQL for data storage, mostly just does CRUD operations (but on arbitrarly complex structures), provides a WCF interface for rich Silverlight admin and has an MVC3 display (and some basic forms like user settings, etc).

It’s getting quite good at being able to load, display, edit and save any (reasonably) complex data structure, in a user-friendly way.

But, I’m looking towards the future, and want to expand my capabilities (and it would be fun to learn new things along the way as well…) – so I’ve decided (in the light of what’s coming for C#5…) to try to get some parallel/async optimalization… Now, I haven’t even learned TPL and PLinq yet, so I’m happy for any advice there as well.

So my question is, what are possible areas where parallel processing maybe of help, and where does TPL and PLinq help me on that?

My guts tell me, I could try saving branches of a data structure in a parallel way to the database (this is where I’d expect the biggest peformance optimalization), I could perform some complex operations (file upload, mail sending maybe?) in a multithreaded enviroment, etc. Can I build complex SL UI views in parallel on the client? (Creating 60 data-bound fields on a view can cause “blinking”…) Can I create partial views (menus, category trees, search forms, etc) in MVC at once?

ps: If this turns into “Tell me everything about parallel stuffs” thread, I’m happy to make it community-wiki…

Answer 1

Remember that an asp.net web application is intrinsically a parallel application in any case. Requests can be serviced in parallel and this will all be managed by the asp.net framework. So there are two cases:

1. You have lots of users all hitting the site at once. In which case the parallel processing capability of the server is probably being used to capacity in any case.

2. You don’t have lots of users all hitting the site at once. In which case the server is probably quite capable of dealing with the responses without parallel processing in a suitable fast response time.

Any time you start thinking about optimising something just because it might be fun, or because you just think you should make stuff faster then you are almost certainly guilty of premature optimization. Your efforts could almost certainly be better spent enriching the functionality of the framework, rather than making what is probably a plenty fast enough solution a little bit faster (at the cost of significantly increase complexity).

In answer to the question of where can TPL and PLINQ really help. In my opinion the main advantage of these technologies is in places in the application where you really do have a lot of long running blocking processes. For example if you have a situation where you call out several times to an external web service – it can be a significant advantage to make these calls in parallel. I would strongly question whether writing to a local database – or even a database on a different box on a local network would count as being a long running blocking process to the extent that this kind of parallelisation is of any significant value.

Pretty much all the examples you list fall in to the category of getting the PC to do something in parallel that it was previously doing in sequence. How many CPUs are on your server – how many are really free when the website is under load. Making something parallel does not necessarily equate to making it faster unless the process involved has some measure of time when you PC is sitting around doing nothing waiting for an external event.