PRACTICAL 1: PERFORMANCE TESTING

PRACTICAL 1: PERFORMANCE TESTING

In software engineering, performance testing is in general, a testing practice performed to determine how a system performs in terms of responsiveness and stability under a particular workload. It can also serve to investigate, measure, validate or verify other quality attributes of the system, such as scalability, reliability and resource usage.

It is not possible to generate the load using the actual physical use, so a use of a software is done so that a simulated environment can be created. Such software will give you look and feel like actual user exists.  Example: Load runner, J meter, Capybara.

                                       Figure 1 load runner                               Figure 2-j-meter

Why to do Performance Testing?

In brief, performance tests reveal how a system behaves and responds during various situations. A system may run very well with only 1,000 concurrent users, but how would it run with 100,000? In terms of performance, we wish to achieve high speed, scalability, and stability of the system.

SPEED: To check the speed / response time for the intended User. Sites that load fastest have a competitive advantage. Since everything on the internet is just a click away, it is vital to have quick load times to keep customers on your site and not your competitor’s. “Two hundred and fifty milliseconds, either slower or faster, is close to the magic number for competitive advantage on the Web.”

SCALABILITY: Not only is speed an important goal for performance, but scalability tests are extremely important if you want more users to interact with the system. How many more users can you support if you add another CPU to the database server? How long will the page take to load with this addition?

STABILITY: Is the application stable under expected and unexpected user loads? (AKA Robustness)

 Confidence: Are you sure that users will have a positive experience on go-live day?

When to do Performance Testing?

performance testing should be a major priority before releasing software or an application. It should be implemented early on in development so as to catch more bugs earlier and increase user satisfaction while saving you time and money down the line. During designing phase, Development phase and deployment phase testing should be done to gain the desired results from our software/websites.

What should be tested?

Ø  High frequency transactions: The most frequently used transactions have the potential to impact the performance of all of the other transactions if they are not efficient.

Ø  Mission Critical transactions: The more important transactions that facilitate the core objectives of the system should be included, as failure under load of these transactions has, by definition, the greatest impact.

Ø  Read Transactions: At least one READ ONLY transaction should be included, so that performance of such transactions can be differentiated from other more complex transactions.

Ø  Update Transactions: At least one update transaction should be included so that performance of such transactions can be differentiated from other transactions.

Performance Testing Process

Below is a generic performance testing process

Figure 3-Testing Process

1. Identify your testing environment - Know your physical test environment, production environment and what testing tools are available. Understand details of the hardware, software and network configurations used during testing before you begin the testing process.
2. Identify the performance acceptance criteria - This includes goals and constraints for throughput, response times and resource allocation.  It is also necessary to identify project success criteria outside of these goals and constraints. Testers should be empowered to set performance criteria and goals because often the project specifications will not include a wide enough variety of performance benchmarks.
3. Plan & design performance tests - Determine how usage is likely to vary amongst end users and identify key scenarios to test for all possible use cases. It is necessary to simulate a variety of end users, plan performance test data and outline what metrics will be gathered.
4. Configuring the test environment - Prepare the testing environment before execution. Also, arrange tools and other resources.
5. Implement test design - Create the performance tests according to your test design.
6. Run the tests - Execute and monitor the tests.