A simple, little web load tool

There are many ways of doing performance testing of web applications. In the good ol’ days I remember starting up Microsofts Application Center Test (ACT) and recording some vbscripts that could later be executed. Nowadays ACT is a lot sexier – but now it comes with Visual Studio 2010 but unfortunately only in Ultimate edition. I tried to persuade my wife to spend the $11000 on the ultimate edition – but she failed to see why this was more important than buying her a car.

Another good option is to use WebLoad. It’s a neat tool – and even if you buy it (to actually get a compiled and running version instead of the do-it-yourself-open-source) it still comes at a more decent price point. I recently played around with it – and it does solve a lot of your performance testing needs – but it’s almost a bit too much overkill for my need (which is essentially to find out how many request/s a web site can handle). I also didn’t like that it hijacked all my browsers and forced them to go through a proxy (in order for it to record what was going on) – and then failing to reset the proxy selection afterwards.

In the end I decided to spend the 30 min it would take to do a simple little performance tester of my own – that does exactly what I want it to.

I came up with AWebLoadTesting which is a compact and ultra-simple console app. It takes an input file which is essentially a text file with a list of urls to visit for each visitor during the test, an output filename – in which it will put a csv file with saved statistics – and that’s about it. If you need to you can also specify a hostname to run the test against – and even a custom UserAgent for the requests.

When it starts you have 0 visitors active. Then, by pressing “+” you can add visitors one at a time – and by pressing “1” and “5” you can add chunks of 10 or 50 visitors at a time. Each visitor is started in its own thread and will continuously go through the urls from the input file again and again.

“u” updates your view, “r” resets the counters", “s” saves the current data to the output file, “-“ removes a visitor” and of course “q” quits.

You’ll constantly be presented with the measured numbers: Time measured (s), Requests / s, Visitor count, Max load time, average load time and min. load time. On top of that it will show you a prioritized list of which urls are the slowest to return. That’s it.

The screenshot above is a test against a local EPiServer CMS 6.0 web site on my laptop, running with ASP.NET caching turned on (Set cache-expiration to 1h in episerver.config, site settings).

Download the binary here and the entire project here. Use AS-IS, LGPL 2.0, Quick&Dirty.

Visual Studio 2008: Application Cannot Start

 

I got this annoying error, every time I tried to run my VS2008 SP1 in Administrator mode (which is needed to avoid the “Failed to map the path '/'.” when running an EPiServer site in visual studios web server). Some google searches brought to outdated microsoft material – but luckily also to Alex Riley’s helpful post: https://www.21concepts.com/Blog/EntryId/10/Visual-Studio-2005-2008-The-application-cannot-start.aspx.

On my win7 x64, it turned out (thanks procmon) that my visual studio was looking for C:\Program Files (x86)\Microsoft Visual Studio 9.0\Common7\IDE\dte80a.olb – and once I copied that from C:\Program Files (x86)\Common Files\microsoft shared\MSEnv all was well.

HTTP Error 500.19 – Internal Server Error

A couple of times I have now run into this wonderful error after setting up a new EPiServer CMS site on a newly installed machine. However, I don’t think it’s specific to EPiServer CMS – but can occur in any asp.net application. The error message looks like this:

The requested page cannot be accessed because the related configuration data for the page is invalid.

As with many other microsoft errors, this is completely misleading (unless you’ve been messing up your configuration data – but this is a newly installed site).

The error message tries to clarify itself further:

Module
IIS Web Core

Notification
BeginRequest

Handler
Not yet determined

Error Code
0x80070021

Config Error
This configuration section cannot be used at this path. This happens when the section is locked at a parent level. Locking is either by default (overrideModeDefault="Deny"), or set explicitly by a location tag with overrideMode="Deny" or the legacy allowOverride="false".

Config File
\\?\C:\EPiServer\Sites\MyEPiServerSite3\web.config

 

By now, you are probably half way into your web.config, and trying to remember where that mystical machine.config is located. You might even have started to go through all directories on your machine in the search for another web.config thats somehome conflicting. Stop looking. It’s not conflicting. And relax – you didn’t do anything wrong…yet.

One of 2 things have likely happened:

1) IIS was installed after ASP.NET, and it’s not really sure what to do with ASP.NET code. Solution: In a command prompt run aspnet_regiis. It’s typically found in “%windows%\Microsoft.Net\Framework\v2.0.50727\aspnet_regiis –i”. Note that you need to run it as Administrator on Vista and Windows 7. In fact, running this can be a cure for many initial web server errors on newly installed asp.net applications.

2) You are running Windows 7 or Windows Server 2008 and you selected the default install of IIS7.5. For reasons known only to Microsoft, they decided that ASP.NET shouldn’t be included in a default installation. My personal theory is that the guy who made that wise call is probably the same guy who decided to remove the ability to drag files onto a command-prompt in Vista. And before that was the mastermind behind the “Copy File” feature in any earlier version of Windows. But I digress :-) Solution in this case is easy – Open Control Panel | Programs | Turn Windows Features on and off, find IIS and enable ASP.NET:

Hit “Ok”, wait for half an hour and then see your web application spring to life. Enjoy!

Skype and Port 80

This is probably old news to a lot of people, but I just ran into an error message in IIS7 on my Vista saying that "The process cannot access the file because it is being used by another process" whenever I tried to start my default website.
Ah well, I thought...Better shut down various other applications although I was wondering what file it could possibly be that there was a sharing conflict on. So, all other app's seemingly shut down, but I still couldn't start my website.
Before I got the error I had been spending numerous hours getting more and more annoyed at IIS7 so I concluded that this was probably something caused by yet another pseudo-paranoid default security setting somewhere - and I guessed that the error was probably misleading and in fact not related to files at all.
Luckily at this point Ruwen came to my rescue and pointed out the obvious that I somehow had missed:
Ruwen: "it could be skype blocking the port 80"

And it turned out that he was (as always) right. Skype listens by default on port 80 and thereby blocks the device (LISTEN on 80) that IIS is using when starting a site.
After visiting Skype's advanced settings and turning off that obscene feature saved my day.