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c#multithreadingasp.net-mvc-3
Joe Enos
Joe Enos

Reputation: 40393

Using threads or tasks with MVC3 AJAX calls

I have an MVC3 project with .NET 4.5 (we can't upgrade to MVC4 for various reasons). I have a need to run three database queries, each of which takes a couple seconds, to populate three sets of data in an AJAX request.

My initial thought was to just make 3 separate AJAX calls, but I ran into issues with maximum concurrent AJAX requests - we have a lot of other AJAX calls going on at the same time, so these 3 were blocked on the client while waiting for all the calls to clear.

So I'm trying to put it in a single AJAX call, but I still want to execute the three queries simultaneously.

Since it's MVC3, I apparently can't do the simple async Task<JsonResult> with await Task.WhenAll(tasks) on three tasks.

I haven't done a lot of multi-threading other than simple "fire-and-forget" stuff, so I want to make sure I'm doing this right.

The following simple way works properly, but I'm pretty sure it's not the right way - I've read a lot of people talking about how ASP.NET is picky about thread handling, especially as you start to use a lot of threads.

var threads = new List<Thread>();
threads.Add(new Thread(() => x1 = Method1()));
threads.Add(new Thread(() => x2 = Method2()));
threads.Add(new Thread(() => x3 = Method3()));
threads.ForEach(t => t.Start());
threads.ForEach(t => t.Join());
// x1, x2, and x3 are now populated

What do I need to change in order to properly use the ThreadPool or whatever other threading techniques I should be considering, and make sure I close things properly? The site generally has only a few dozen concurrent users, and this call would be made whenever they load up a page - so it's not a huge number of threads.

I'll also add exception handling to make sure nothing blows up.

Upvotes: 3

Views: 378

Answers (1)

Erik Philips
Erik Philips

Reputation: 54618

What do I need to change in order to properly use the ThreadPool or whatever other threading techniques I should be considering, and make sure I close things properly?

It depends.

Your current code won't reuse a thread from the thread pool and possibly thread-starve the PoolThread causing a 500 (ASP.Net request processing stalled because the CLR thread pool is out of threads). There is a small performance penalty for bringing up a new thread (which is why the thread pool exists in the first place), but for high through-output high concurrency websites, this is a good choice.

That being said, if your website is servicing a low through-output low concurrent user base, it's over kill in my opinion. It's much easier on the eyes (opinion) to use the Task.Factory. This will use thread in the thread pool, but unless you're running the website on a single-core machine, I doubt anyone will notice.

Outside of the threading models, there are much more architectural ways to reduce database hits, but your question is so specific, there isn't much I could suggest without knowing more.

Upvotes: 2

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