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Performance Testing 101

So one of my objectives is to be able to offer more in regards to Performance Testing.

Whilst I understand the basics, I figured I'd write them down and start a series of blog posts hopefully detailing my findings and explaining why performance testing is important, and the different types of performance testing.

In order to understand why performance testing is important, it will be good to know some of the more popular types of performance testing are....

Load Testing
This is testing a system to understand and analyse the behaviour of a system under a specific expected load. This is probably the most common form of performance testing, it is useful in identifying any bottlenecks in a piece of software. 

Stress Testing
This is testing a system to breaking point, so that you can understand the point at which the system fails and under what load.

Endurance Testing
Similar to load testing, but this will be load under a prolonged period of time, in order to gain confidence that the system can perform under loads for a long period and measuring the performance of the system.

Spike Testing
This is achieved by a sudden increase in load against a system, to make sure that it can handle the sudden increase in users, an example would be of a new system going into production that suddenly has to deal with a huge influx of users.

When might you use one of the above?
Now you have a basic understanding of some of the different types of performance testing, we can now look at where they may be useful, and when you might consider doing one of the above.

Load Testing is possibly one of the more well known and what often gets confused as Performance Testing full stop, when someone mentions performance testing, it is often assumed that they are talking about load testing, however, unless we dig deeper, assuming something like that can make an ass out of you and me...

Anyway, I digress, Load Testing would be useful when there is a change to the system that can cause there to be an increased amount of load, for instance we recently changed data types from VARCHAR to NVARCHAR, this meant there was double the amount of data being stored in databases and being used in any database call, so we decided its important to do some forms of load testing on the front end, as well as the back end on the SPROCs themselves.

Stress Testing is useful to identify what your system is able to cope with, for example, if you were expecting X number of visitors during a certain period of time, if you know what your break point is, with regards to stress testing, you can safely say that the system can perform under the expected load and then some.

Endurance Testing is useful in identifying memory leaks in a system, if you expect the system to be under heavy loads for a prolonged period of time, it is essential to perform endurance testing to identify any problems that may arise.

Spike Testing as mentioned above is useful when putting a new service live, as you expect a sudden increase in traffic once it goes into production and will be hit with a sudden influx of load.

So, there you have it, some basics about the different types of performance testing, and why it might be important in your project.... Going forward we'll investigate different toolsets for performing the above and when is the best time to do performance testing in an Agile project.

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