Sunday, January 19, 2014

Inconvenient MVC Web Optimization Framework and High CPU Utilization

While I am writing this post I am bit relaxed and listening to 'bollywood' music so don't wonder if you find anything off topic or typos :), lazy weekend!!

What was the issue?

Last week, while working with the Window azure cloud services we tried to stress test it and guess what we found? CPU spikes!!
Initially we thought that this might be something related to load on the server as it was a small VM instance but at the same time the results were unbelievable as number of concurrent requests to the server were comparatively less. This gave us the kick start and we started to drill down to the real issue.

The approach:

It all started with several meetings with few brainy people around as I was clueless, some even directly said man your application got memory licks..but then
Thanks to the Visual Studio profiling framework which helped me a-lot to drill down into real issue about this CPU spikes. You can read about how to use this feature and how it helps in my blog post here Profiling windows azure cloud services - http://passionatetechie.blogspot.in/2014/01/profiling-for-windows-azure-cloud.html

When I tried to stress test the service and tried to collect the profiled logs , found that there were these two methods which were taking almost more than 80% of CPU, wowwwwww!!
1. Scripts.Render
2. Styles.Render

 Note - I was using ASP.NET MVC web optimization nuget version 1.0

Irony is, these methods are from the web optimization framework of ASP.NET MVC which is suppose to improve the performance of your web application by bundling the java-scripts and css files. More info about bundling here - http://www.asp.net/mvc/tutorials/mvc-4/bundling-and-minification

All right then of course the straight way to remove these calls from application and try to stress application again and check results. we did exact same thing and this time application performed pretty well!! no CPU spikes!! man bingooo!!!!!!

But then why in my application the optimization framework was doing something like this? why ? why why and why.......? this question even appeared in my dreams!!
I started search around it but didn't find something helpful, I even started doubting my decision about removing those calls from the application unless I hit this post here
http://stackoverflow.com/questions/14210721/mvc-4-on-azure-scripts-render-bundles-jquery-slow and
http://stackoverflow.com/questions/12230246/azure-cache-preview-outputcache-high-cpu-slow

Here is why and it is purely based on what I understood

When you use the bundling (Web optimization framework) - server uses the caching.
But now as you are mentioning the setting in your web.config file that you are not using default caching of server anymore instead you want to use the Windows azure distributed cache.
Like this


<caching>
  <outputCache defaultProvider="DistributedCache">
    <providers>
      <add name="DistributedCache" 
type="Microsoft.Web.DistributedCache.DistributedCacheOutputCacheProvider, 
Microsoft.Web.DistributedCache" cacheName="default" dataCacheClientName="default" />
    </providers>
  </outputCache>
</caching>

So seems this web optimization framework doesn't understand this distributed cache and it simply ignores the caching part.
Due to this it tries to recompile your bundles every time with each request which causes higher CPU utilization.


I also had the distributed cache related settings in my application's web.config , so I decided to remove both from my application i.e. Bundling as well as distributed caching - it worked and CPU utilization never touched the boundary.


Takeaways:

In case you are facing the same issue of high CPU consumption on the web server in your ASP.NET MVC application or cloud service then
1. Run the VS Profiler locally and see whats the root cause of it
2. If you find the Optimization framework APIs are taking most of the CPU then try removing it and stress your application again to see the results.

Next step:

According to this link http://aspnetoptimization.codeplex.com/workitem/46 , its the discussion on codeplex on very same issue but If you go to the comments section then someone said that they have fixed it in the next version of nuget. (i.e. post version 1.0)
I havent tried using next version of this nuget but when I will do it I will update this post.

Hope this helps and stops wondering someone about why my CPU percentage is higher when using web optimization framework of MVC.







Saturday, January 18, 2014

Profiling Windows Azure Cloud Services

Hi again guys,

Last week I was working really close with performance related things of the web applications and this what I came across for Windows Azure Cloud services.

Profiling is one of the great feature of Visual Studio and I almost fell in love with it. why? because first of all its quite descriptive and helps to measure the memory / CPU monitoring of your application and second is it can be configured in both ways i.e. while running your application locally as well as while running your application in the cloud.

I will not go into much deeper on how to use this feature and how it helps, all you need to do is click on the link to know and you are done.
http://msdn.microsoft.com/en-us/library/2s0xxa1d.aspx

You can use this great feature to go into the quite deeper understanding in terms of how your application is consuming resources on the server and it helps in deciding to scale up or scale down your application needs. More information on it at http://msdn.microsoft.com/en-us/library/dd264994.aspx

But all right , lets come back to the Cloud arena and let see how can use this for Windows Azure cloud services.

basically you can use this feature while deploying your application using VS to cloud deployment wizard. (Publish)

A great article http://msdn.microsoft.com/en-us/library/windowsazure/hh369930.aspx#BK_ProfilingCloudService which explains the approach about how you can do it pretty easily while deploying to Azure through your VS.

I was interested more on what special this VS does when we check the check box of Enable Profiling in the publish wizard? and here is what I found

Basically VS adds few entries in your cloud service definition and cloud service configuration files.

(I am using Windows Azure SDK 2.2)

In csdef
 <InternalEndpoint name="Microsoft.WindowsAzure.Plugins.Caching.cacheArbitrationPort" protocol="tcp" />
  <InternalEndpoint name="Microsoft.WindowsAzure.Plugins.Caching.cacheClusterPort" protocol="tcp" />
  <InternalEndpoint name="Microsoft.WindowsAzure.Plugins.Caching.cacheReplicationPort" protocol="tcp" />
  <InternalEndpoint name="Microsoft.WindowsAzure.Plugins.Caching.cacheServicePortInternal" protocol="tcp" />
  <InternalEndpoint name="Microsoft.WindowsAzure.Plugins.Caching.cacheSocketPort" protocol="tcp" />


In cscfg
<Setting name="Profiling.ProfilingConnectionString" value="YourStorageAccount" />
<Setting name="CloudToolsDiagnosticAgentVersion" value="2.2" />


But then I also found that the size of the deployment packages increases when you enable this option of profiling, and that's because VS also adds the 64 bit profiler in your package.
So I am not sure about how you can use this feature when you dont want to publish using VS to your cloud service, however article http://michaelwasham.com/2011/08/10/deployment-to-windows-azure-fails-with-profiling-enabled/ explains how can you do it but as it is written for older version of SDK so I am doubtful if this works for later versions of Windows Azure SDK.

Overall profiling feature managed to impress me with with it's native integration with Windows Azure Cloud Services.

Once you enable the profiling and deploy the cloud service, VS 2012 Server explorer helps you in getting report out of your profiling build with just a single click and you are set to analyze the report.

Monday, January 13, 2014

Converting Lists to Collections in C# and Using Linq on it

All right guys, this one is one of the shortest blog post I am doing today and hope it helps people like me who wasted almost few minutes searching for solution on this.

Basically .NET Framework offers us too many collections however two of those are
1. List
2. Collection

We all know Linq, i.e. this nice and slick feature of .NET to query various collections however when it comes to Collections then we get this famous typecasting error
i..e Cannot convert IEnumerable to Collection etc etc..

Well, after several minutes of discussion with my brainy peers and some search on internet here is what I have done

Its a workaround which works in two steps
1. Convert your Collection to List and perform Linq on it.
2. Convert back your List to Collection. How? here we go

Collection<Entity> collection = new ObservableCollection<Entity>(collection.ToList().Distinct());

And you are done.

Hope this helps someone.