CODEWITHSUNDEEP
c#.netcachingazure
Adam
Adam

Reputation: 16199

Using InProc and Azure AppFabric Cache together

Just a bit of background first. I currently have a site hosted with Windows Azure, with multiple instances and also AppFabric as my sole caching provider.

Everything was going great until my traffic spiked earlier this morning. After the instances became overloaded and stopped responding everything came good again once the new instances started.

However I started getting messages from AppFabric saying that I was being throttled because there were too many requests in a given hour. Which is fair enough, it certainly was giving it hell.

In order to avoid these messages in the future I was planning on implementing an InProc cache for very short lifespan. So it checks InProc first, if not goes to AppFabric, if not goes to DB.

 ObjectCache cache = MemoryCache.Default;

 CacheItemPolicy policy = new CacheItemPolicy();
 policy.AbsoluteExpiration = DateTimeOffset.Now.AddMinutes(5);

The questions I have are

Update I just wanted to say I chose the above method and it works well. I was using it only for general data storage and not session state. MemoryCache with session state would not work too well on Azure due to no server affinity (as mentioned by David below).

Update 16-03-2012 After realizing the obvious I also disabled SessionState on most pages. Most of my pages don't need it and hence this rapidly decreases my calls to cache under heavy load. I also disabled ViewState for most pages as well, just for that slightly quicker page load time.

Upvotes: 3

Views: 1006

Answers (5)

Brian Reischl
Brian Reischl

Reputation: 7356

Are you using cache to provide SessionState storage, or general data storage by your application, or both? It's not totally clear, because InProc usually refers to SessionState, but your sample code does not look like SessionState.

Assuming that you're storing data which can be safely cached locally, then I would recommend looking into AppFabric Local Caching. It does basically what you want, and doesn't require writing any separate code (I think...).

Otherwise, using MemoryCache as you outlined is a workable scheme. I've done this in my apps, you just need to be careful to avoid cache incoherence issues.

Depending on your application, you may also want to implement a per-request cache by storing data in the HttpContext.Items collection. This is helpful when different parts of your code might request the same data during a single request.

Upvotes: 2

Tom
Tom

Reputation: 1611

Another possible solution would be to use Sticky Sessions like this example:

http://dunnry.com/blog/2010/10/14/StickyHTTPSessionRoutingInWindowsAzure.aspx

Upvotes: 1

David Makogon
David Makogon

Reputation: 71031

I wouldn't suggest inproc, due to the fact there's no server affinity.

One option, with With Windows Azure Cache, to avoid the hourly quota throttling is to bump up cache size. Fortunately the price doesn't scale linearly. For instance: $45 for 128MB, $55 for 256MB. So one option is to bump up your Cache to the next size. You'll need to monitor Compute performance though, via perf counters, as there's no way to monitor cache usage realtime.

Another option is to move session state to SQL Azure, which is now an officially-supported session state provider as of Azure 1.4 (Aug. 2011 - see this article for more info). With the latest SQL Azure pricing updates, if the db stays below 100MB, it's a $4.99 monthly rate instead of the original $9.99 baseline. It's amortized daily, so even if you have transient spikes and go into 1+GB range, you still have quite an affordable cache repository.

Upvotes: 1

RichBower
RichBower

Reputation: 204

Try this: http://msdn.microsoft.com/en-us/magazine/hh708748.aspx

Upvotes: 1

Craig
Craig

Reputation: 36816

One thing I have done is use HttpContext.Items. This is only a per request cache but depending on the nature of your system can be useful.

Upvotes: 1

Related Questions