Asynchronous WCF Web Service Load Testing - wcf

Question

I see several other questions about load testing web services. But as far as I can tell those are all synchronous load testing tools. (Meaning they send a ton of requests but the go one at a time.)
I am looking for a tool where I can say, "I want 100 requests to be launched at the exact same time".
Now, I am new to the whole load testing thing, so it is possible that those tools are asynchronous and I am just missing it.
Anyway, in short my question is: Is there a good tool for load testing WCF Web Services asynchronously (ie lots of threads).

Answer 1

In general, I recommend you look at soapUI, for anything to do with testing web services. They do have load testing features in the Professional edition (I haven't used these yet).
In addition, they've just entered beta with a loadUI product. If it's anywhere near as good as the parent product, then it's worth a hard look.

Answer 2

you can use the Visual Studio load testing agent components to run on multiple client machines and that will allow you to run as asynchronously as you have machines to load.
There is a licence requirement for using this feature.
There are no tools that will allow you to apply a load at exactly the same instant (i.e. within milliseconds), but this is not necessary to load test an application correctly.
For most needs a single load test server running Visual Studio Ultimate edition will be more than enough to get an understand of how your webservice performs under load.
Visual Studio and most other tools I imagine will apply load in an asynchronous manner, but I think in your view you want to apply a set load all at once.
This is not really necessary as in practice load is not applied to a service in this manner.
The best bet for services expecting high load is to load your service until a given number of "requests per second" is reached. Finding what level your application should expect is a bit trickier, but involves figuring out roughly how many users you would expect and the amount they will be using it over a given period.
The other test to do is to setup a load test harness and run the load up until either the webservice starts to perform badly or the test harness runs out of "oomph" and cannot create any more load.

Answer 3

For development time you can use NLoad (http://nload.github.io)
to run load tests on your development machine or testing environment.
For example
public class MyTest : ITest
{
public void Initialize()
{
// Initialize your test, e.g., create a WCF client, load files, etc.
}
public void Execute()
{
// Send http request, invoke a WCF service or whatever you want to load test.
}
}
Then create, configure and run a load test:
var loadTest = NLoad.Test<MyTest>()
.WithNumberOfThreads(100)
.WithDurationOf(TimeSpan.FromMinutes(5))
.WithDeleyBetweenThreadStart(TimeSpan.Zero)
.OnHeartbeat((s, e) => Console.WriteLine(e.Throughput))
.Build();
var result = loadTest.Run();