LoadRunner Interview Questions and Answers -3
1) How do you identify the performance bottlenecks?
Performance Bottlenecks can be detected by using monitors. These monitors might be application server monitors, web server monitors, database server monitors and network monitors. They help in finding out the troubled area in our scenario which causes increased response time. The measurements made are usually performance response time, throughput, hits/sec, network delay graphs, etc.
2) What are the tools available in the industry for Load Testing?
IBM – RPT (Rational Performance Tester)
Micro Focus – Silk Performer
JMeter (Open source Tool)
QA WebLoad (RadView)
3) What are the considerable factors in Performance Result Analysis using LoadRunner?
Performance Bench Marks
Local System Configuration
4) How to identify the memory leakage using Loadrunner?
In Load runner, every application has a processor running in the system. The processor needs to be identified. Using the performance tab we can check the memory consumption of the processor. Continuous tracking needs to be done while load testing. However, if the memory keeps increasing even on stopping the test, a memory may have occurred. Also, if the memory is not released on stopping the test, a memory may have occurred.
5) How do we debug a LoadRunner script?
Debugging a LoadRunner script:
VuGen contains two options to help debug Vuser scripts-the Run Step by Step command and breakpoints. The Debug settings in the Options dialog box allow us to determine the extent of the trace to be performed during scenario execution. The debug information is written to the Output window. We can manually set the message class within your script using the lr_set_debug_message function. This is useful if we want to receive debug information about a small section of the script only.
6) What are the performance tester roles and responsibilities using loadrunner?
There won’t be load runner roles and responsibilities. It is the roles of performance engineer and there won’t be difference between the roles what ever tool you use for performance testing.
7) When do you do load and performance Testing?
We perform load testing once we are done with interface (GUI) testing. Modern system architectures are large and complex. Whereas single user testing primarily on functionality and user interface of a system component, application testing focuses on performance and reliability of an entire system. For example, a typical application-testing scenario might depict 1000 users logging in simultaneously to a system. This gives rise to issues such as what is the response time of the system, does it crash, will it go with different software applications and platforms, can it hold so many hundreds and thousands of users, etc. This is when we set do load and performance testing.
8) Do you feel like performance testing is an accepted critical part of the development life cycle?
It is getting that way yes, with more and more crashes getting exposure on the news here and with it happening more and more it has become a critical part of testing.
10) What are the key KPIs you track for performance testing and tuning?
The key KPIs that we track for performance testing are transaction response time, memory usage, disk space, and CPU time.
Tuning: Network delay and stored procedure times.
11) What is Throughput?
Basically, “Throughput” is the amount of transactions produced over time during a test. It’s also expressed as the amount of capacity that a website or application can handle. Also before starting a performance test it is common to have a throughput goal that the application needs to be able to handle a specific number of requests per hour.
12) What is peak load testing?
Peak load is the maximum amount of concurrent users that are on a website within a certain time period. For example, if you own a retail website, your peak load during any given week is most likely to be on the weekend. It would also follow that the Thanksgiving and Christmas holiday season is your busiest overall.
13) What is the focus of Performance testing?
The focus of Performance testing is checking a software program’s
• Speed – Determines whether the application responds quickly.
• Scalability – Determines maximum user load the software application can handle.
• Stability – Determines if the application is stable under varying loads.
14) What is the goal of performance testing?
The goal of performance testing is not to find bugs but to eliminate performance bottlenecks.
15) Can anybody give me example for load testing?
Load testing will simulate a real time user load on the application and testing.
For example: Searching functionality in a website.
If a website needs to accommodate a certain number of simultaneous users, for instance 1000 people using the search engine at the same time, then the site should be tested for that load before putting the website into production. Each of these 1000 visitors can access this website with different browsers, different versions of the same browser, different machines in different platforms. Their connections can range from high-bandwidth data lines to dial-up. Load testing is designed to verify that the website can handle the expected load.
16) What is Endurance Testing?
Endurance Testing means testing is done with expected user load sustained over longer period of time with normal ramp up and ramp down time and to identify Memory Leaks.
17) What is Volume Testing?
Volume testing is a typical load testing except that a large volume of data is populated on the database to study its impact on the application response time and database overall health ; Behavior at various DB volumes.
E.g. Checks for Accumulated counts, logs, and data files.
18) What is Scalability Testing?
Scalability testing is a process of evaluating the systems behaviour when the number of simultaneous users is increasing, and the hardware and software resources are fixed. This testing will be conducted for comparing the response times and system resource utilization of AUT when the number of users are increased.
19) What are the results reported after capacity Testing?
Results Reported after capacity Testing are:
• The hardware resource related bottlenecks will be reported.
• Recommendation on new hardware.
• Up-gradation of existing hardware.
• Change in the existing application deployment architecture to support the future growth.
• Introducing new servers in the application deployment architecture.
20) What are the results reported after Stress Testing?
Results Reported after Stress Testing are:
1. The maximum number of users supported by AUT.
2. Let us assume that, the system resources are utilized beyond the expected limits. After the stress test, when the normal amount of users are running, the status of the application in terms of the resources utilization will be reported.
3. Assume that there are many errors are coming when the stress testing is been conducted. After the stress test, when the normal amount of users are running the status of the application in terms of the errors will be reported.
21) What are the disadvantages of using commercial performance / load testing tools?
Disadvantages of using commercial performance/load testing:
We need to understand the need for any commercial tool with respect to the kind of technologies we use in your organisation. A tool that do not support the technologies is waste of time and money. If it can fit into our requirements, there is a considerable ROI.
22) How do you test an application if it is going production for the first time?
For testing the application, you need to have the basic scenarios done first.
Second step will be to do the End to End testing with E2E scenarios.
Third test will be to do the rigorous testing.
Final step will be to do the load testing.
23) Why should we automate the performance testing?
Its a discipline that leverages products, people and processes to reduce the risk of application, upgrade or patch deployment. It is about applying production work loads to pre-deployment systems while simultaneously measuring system performance and end-user experience.
24) What are the results reported after the Endurance/Longevity/Soak Testing?
Results Reported after the Endurance / Longevity / Soak Testing Test:
When the endurance test is conducted on a multi tier web based enterprise level applications the following kind of results will be reported.
• Memory leaks on the application servers
• JVM Heap size utilization on the application servers
• Connection leaks on the database server
• Cursor leaks on the data base servers
• Response time (consistency or degradation) comparison for start of the load test to end of the load test
• Systems Resource (Memory, CPU, Network and Disk usage etc) comparison for beginning of the load test to end of the load test
• Application errors occurrence over the period of time.
25) What are all the things will be considered while doing performance testing?
Does the application respond quickly enough for the intended users?
Will the application handle the expected user load and beyond?
Will the application handle the number of transactions required by the business?
Is the application stable under expected and unexpected user loads?
Are we sure that users will have a positive experience on go-live day?
26) What are the results reported after the load Testing?
Results Reported after the load Test:
• The system will be validated to ensure whether the service level agreements or performance objectives are met.
• Average, max, min and standard deviation of response times for each scenario will be measure and reported.
• Resource utilization of each of the systems which are part of AUT will be monitored and reported.
• If there is any application break point below the peak load condition, it need to be identified and reported.
27) What are the results reported after Spike Testing?
Results Reported after Spike Testing:
• The systems resources are utilization comparison for, with and without spikes.
• The response times comparison for, with and without spikes.
• Observation on errors for, with and without spikes.
28) What is remote command launcher?
The remote command launcher enables the controller to start applications on the host machine.
29) How to determine the Stress Point?
Determining the Stress Point:
• Transaction response times are exponentially increased
• The application started throwing the errors for many users
• The system stopped responding
• At least one of the server in AUT architecture got crashed
• The system resource utilization went beyond the acceptable limits.
30) What are the results reported after Scalability Testing?
Results Reported after Scalability Testing:
• The comparison charts of different number of users and their response times.
• The comparison charts of system resource utilization for different amount of users.
• Scalability issues when the number of users are incremented.
• Identification of scalable point of the application.
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