Before understanding the complexity that is involved in testing the software using load testing methods, it is important to know that load testing is part of performance testing first. It is also crucial for you to understand that unlike other kinds of testing, the main purpose of performance testing is not to find bugs and errors in this system. Rather, the concept revolves around eliminating the different bottlenecks that are involved in a system process.
Having a streamlined set of system will enable it to make a baseline where for regression testing that will be conducted in the future. Load testing is an important test in the life of a software application. Load tests are end-to-end tests that are performance-oriented, under an anticipated or expected production load.
The main goal of load testing test is to find out the basic response times for different time critical applications and ensure that they remain within the accepted levels of performance. Load tests will also help you measure the capability or ability of an application to function or work in the right manner, under any type of load, by quantifying the rates of transaction pass or fail or error rates.
There are two essential things to load testing. The first essential aspect you should know is the expected load of the http connections and the concurrent users. Then, you should also know the response time that is expected for these applications. Once you know these two things, you can now start the testing by constantly putting more loads into the system. This will enable you see bottlenecks that may be present in the system. Nevertheless, you should note that these bottlenecks may be present in different levels, so you need to have some tools that will help you pinpoint where the bottlenecks are.
Here are the different levels and the tools you must use to eradicate the bottlenecks:
(1) Application level: Here, software developers can make use of profilers to see the inefficiencies that may be present in the code.
(2) Database level: Software developers need to use specific profilers for the database to spot the bottlenecks in this case. It is also possible for them to make use of query optimizers to correct the said errors.
(3) Operating level: In this third level, it is recommended for software developers to use different utilities like iostat for UNIX system, PerfMon for Windows, vmstat to be able to monitor the hardware resources. The hardware resources you need to monitor include the memory, the CPU, the disk I/O, and the swap. Otherwise, you can also use the software that can monitor the kernel of the system.
(4) Network level: At this stage, software developers need to work hand in hand with the network engineers to be able to use the packet sniffers to find bottlenecks in the system. These sniffers include the network protocol analyzers and the tcpdump. You should note that there are many kinds of network analyzers like the mii-tool, the MRTG, the ntop, and the netstat.
One thing to note here is that, most of these approaches use the white box testing method where you can inspect the software through different angles and sides. Although this test is effective, you may still need to conduct a black box testing procedure for the load testing approach. For example, when software developers are testing a web application, they can use tools that imitate http connections and then measure the response time.
The result of these tests will then demonstrate if the software meets the required standards. If the result is not satisfactory, then software developers may need to fine-tune the software that starts from the application to the database. It is important to ensure that the software is using the optimal operating system and hardware configurations. However, it is still possible that the software will not meet the required standards even after fine-tuning by the software developers. When this happens, they can use other procedures and some of these procedures include the following:
(1) Making use of cache mechanisms in the internet
(2) Publishing static web pages so these will not affect the database
(3) You can also measure the server horizontally through using load balancing
(4) Meanwhile, horizontally scaling the server and then splitting them into read-only servers and write/read servers will balance the read-only servers.
(5) Then, you can also scale the server vertically through adding additional hardware resources such as the RAM and CPU.
(6) The last alternative you can choose is to increase the bandwidth of the server.
These processes may look simple, but they are very tedious and difficult. You may need to introduce subtle modifications to make software system work in a proper manner. You may need to make very slow and gradual modifications, one variable at every step and by making a careful revision to the measurement. It is also possible to make many changes at once though these procedures will be hard to repeat.
When the software already met the required standards, it would mean that the software developers now have a baseline of what to expect, when they run the software during normal circumstances. These baselines will become useful during the regression test to determine how well the software actually performs. Load test works very well to fine tune the software’s ability to take additional load under any type of computing environment.
Load testing is a part of the performance testing and ensures that the software application works under all types of conditions. The basic concept behind this test is very simple; you will be determining the capacity of the system by increasing the load on the application and this test will let you know the software is functioning properly or not under different circumstances.
In other words, you will be testing the software by increasing the number of tasks until the optimum endurance level is determined. Therefore, load testing is also an endurance testing or volume testing method. However, you should note that endurance testing and volume testing are not the same, although they both fall under load testing under some specific conditions.
You will conduct volume testing for
(1) Testing the capacity of word processor software by putting and trying to edit a large document in it
(2) Testing the capacity of the printer by sending a very large file for printing
(3) Testing a server for mails by making thousands of mailboxes
(4) Zero-volume testing where the system is given empty tasks that it should perform.
On the other hand, another kind of load testing method is the endurance testing. To enable you to differentiate volume testing and endurance testing better, you may need to define what an endurance test is. Endurance test means testing a server application by making the client run a loop against this particular server for a specific period.
Just like any other kinds of software testing, load testing is being conducted for a reason and you can expect many advantages from load testing.
• Load testing will expose the bugs such as undetected memory overflow and memory management bugs in your system.
• Load testing enables you to increase your uptime in your internet system. Load testing can do this because it spots the bottlenecks even before they happen in an actual environment.
• Another advantage is that it can measure the performance of your internet infrastructure. For example, if you are engaged in e-commerce, then you can monitor how your business is doing especially, when there are many concurrent users who hit your site.
• Load testing will also prevent software failures, because it can predict how the system will react when it is given large loads of files and large amount of tasks.
• Still another benefit of load testing is that you will be able to protect your investment, because this kind of testing allows you to have an idea of the scalability and the performance of your software.
Performance test is conducted by adding different load amounts by taking user load testing methods as a benchmarking tool. On the other hand, load testing uses a predefined load amount. When you run load testing, you must have a predetermined amount of load that you will use for the test.
Usually, this predetermined load is the optimum load that the software can tolerate, so you can expect this load amount to be rather large. Meanwhile, the performance testing increases the load amount the software will take incrementally. However, it is impossible to say whether performance testing or load testing is more beneficial, because each of these have its own purpose in testing the software.
In nutshell, load testing is one of the most critical tests in software development activities you ensure that the software you want to launch in the market is as effective as it ought to be. Nevertheless, load testing gives you another significant benefit aside from this, because it ensures that your software will be able to handle large amount of tasks without breaking down or having any errors. Truly, load testing provides an assurance that the software you use is productive.