After IIS7 and later IIS versions, there has been some changes on the way the requests are queued, especially when you use Integrated pipeline. This blog is a very good resource to understand these changes.

Even this is not a new thing, there may still be confusions around using performance counter values, especially, when performing load tests, to see if there are queued requests, after a certain load.

I have created a test scenario, to concretize these differences, and to show you how you can evaluate the change on that pipline mode. See the steps and conclusion below. 

Step-1: I have setup an application pool using Framework V4 and created a test ASP.NET script to work under that application pool.

Test script looks like below, and it blocks a worker thread for 40 seconds.. Just to keep the CLR worker threads busy. I took it as an application, under the application pool i have created on earlier step.

40SecRequest.aspx:

<%@ Page %>
<script language="C#" runat="server">
private void Page_Load(object sender, System.EventArgs e)
{   System.Threading.Thread.Sleep(40000);    }
</script> 

Step-2:  After that, I have decreased the "MaxWorker" threads to only "2" (4 procs machine), to force the queueing up of the requests easily:

 C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Config\machine.config (framework folder is defined with application pool settings.)

..

<system.web>

<processModel autoConfig="false"              
maxWorkerThreads = "2"              
maxIoThreads = "2"              
minWorkerThreads = "1"              
minIoThreads = "1"              
/>

<httpRuntime minFreeThreads="1"              
minLocalRequestFreeThreads="1"              
/>

..

And also I have changed the "maxConcurrentRequestsPerCPU" setting to "3", for "integrated pipeline" to decrease the maximum number of requests to be executed to "3*numberofCPUCores" :

C:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet.config

<?xml version="1.0" encoding="UTF-8" ?>
<configuration>
<system.web>
<applicationPool
        maxConcurrentRequestsPerCPU="3"
        maxConcurrentThreadsPerCPU="1"
        requestQueueLimit="5000"
/>
..

Step-3 : After that I have used that tinyget to pump some requests to the application pool with following command:  

 c:\Utils>tinyget.exe -srv:localhost -uri:/ProcessModelChanged/40SecRequest.aspx -threads:40 -loop:1

Observation : 

On Integrated pipeline:        

• We have "8" requests executing, which is calculated like "numberOfCpuCores * MaxWorkerThreads"  = 8 (4 * 2) , on parallel.
• For “ASP.Net Applications” and “ASP.NET apps” counters “Requests in the application queue" is zero. Because, In integrated pipeline we don’t have application level queues. That is why these counters are zero.
• For “ASP.Net” category “Request queued” is displaying the number of queued requests.

 If I convert the application pool pipeline mode to "Classic pipeline" mode;

• We have now, "7" requests executing on parallel, which is calculated with "(numberOfCpuCores * MaxWorkerThreads )-  minFreeThreads" formulla per this article. This calculation makes "7" (4*2-1) parallel requests getting executed.
• For “ASP.Net Applications” and “ASP.NET apps” counters “Requests in the application queue is now functional , because we have application level queues.
• Also For “ASP.Net” category “Request queued” is displaying the number of queued requests again.

 I hope this was useful for you,

Thanks,

Mert

We are close to the end of November, and you may hear the footsteps of winter coming, for the north!

For the ones, who are following ASP NET 5, it is now open source, cross-platform and portable, more charismatic then ever. Its exciting to see that it is reshaping itself for the Cloud world. We are now, close to the first release such that this month first release candidate (RC1) is unleashed. You can take a look to the road map from github.  

Basically there are 3 main components for ASP.Net 5: 

• DNVM(.Net Version Manager) which lets you to select the version from a list of ASP.Net versions.
• DNX(.Net Execution environment) which is the SDK and run-time environment that has everything to build and run .Net applications, for Windows,Mac and Linux.
• DNU(.Net development utilities) which is fundamental for developing ASP.Net applications. 

With these components, you can develop and build Asp.Net applications which can run on different platforms. Setting up that environment is quite easy and you can follow the guidelines on asp.net website. On an untested version of linux, you may go into some issues, due to prerequisites of DNX especially.

In this blog, i want to make a quick overview of setting up an environment on latest version of Ubuntu - 15.10 (Wily Werewolf) on Hyper-v, and want to tell you the difficulties i had, and you can also have.I also set up "Visual Studio Code" for an IDE and "Yeoman" for a code scaffolding tool. 

The officially supported Ubuntu version for "beta-8" version was "Ubuntu 14.04". Because of this, i got some issues on installation of environment and utilities. One was because of a DNX prerequisite, in particular "libicu", and the other was when setting up "Yeoman". Luckily, there is everything you need on internet to workaround these problems. For a Windows guy like me, that was all i need. Here is a summary of the challenges i had, if you also plan to install DNX on "Ubuntu 15.10":

#1 - First of all, i recommend you to first update the package index before applying the instructions on asp.net site for DNVM and DNX - Coreclr installations. Below command updates the local package index with the latest changed made in the repositories: 

sudo apt-get update

#2 - After you install the "coreclr" with "DNVM", "dnx" and "dnu" commands was not producing any output. With the following trace output (DNX_TRACE is an environment varible), i discovered that i had the same issue on this github article. 

DNX_TRACE=1 dnx --version

It is an issue with the "libicu" module (a prerequisite for DNX) since "Ubuntu 15.10" uses "libicu55" but "Ubuntu 14.04" was using "libicu52". Installing "libicu52" is finxing the issue on "Ubuntu 15.10".

#3 - You may get a warning on Yeoman installation like "node:not found". It is an issue about remaing of Node.js, for a naming collision with another package. As far as i can see, it can be recovered by following command: 

sudo apt-get install nodejs-legacy

After that you can install "yo" with following command.

sudo npm install -g yo generator-aspnet

Finally i have managed to run my first asp.net application on "Ubuntu 15.10" :

Finally i want to give some more small notes about commands for DNVM:

• "-u" switch let you to install the most recent version: "dnvm install -r coreclr latest -u"
• You may also want to work with the samples from asp.net site via cloning them on linux.
• A link of "Visual Studio code" should be added like this, to launch it from Terminal easily:  "sudo ln -s /path/to/vscode/Code /usr/local/bin/code"

These are the major things i recall.

Happy coding!

Mert

I am working as a Support Escalation Engineer in Microsoft, supporting "EMEA premier customers", especially for web based technologies. Previously, I was contributing to a "Turkish blog" named "devtr" with one of my colleagues, and now i will also create blog posts mainly in "English" for my own blogging site here. 

There are many reasons to be excited about how the things changing to adapt to "Cloud" and "Mobile" world nowadays, and i want to share my experiences from here on my daily support business as much as i can. I hope you find it useful!

Mert