Loadrunner Interview Questions & Answers
1) What is the difference between Performance testing and Performance engineering?
In Performance testing, testing cycle includes requirement gathering, scripting, execution, result sharing and report generation. Performance Engineering is a step ahead of Performance testing where after execution; results are analyzed with the aim to find the performance bottlenecks and the solution is provided to resolve the identified issues.
2) Explain Performance Testing Life Cycle.
Step 1: System Analysis (Identification of critical transaction)
Virtual User Generator
Step 2: Creating Virtual User Scripts (Recording)
Step 3: Defining Users Behavior (Runtime setting)
Step 4: Creating Load Test Scenarios
Step 5: Running the Load Test Scenarios and Monitoring the Performance
Step 6: Analyzing the Results
Refer Performance Testing Tutorial #2 for more details.
3) What is Performance testing?
Performance testing is done to evaluate application`s performance under load and stress conditions. It is generally measured in terms of response time of user’s action on an application.
4) What is Load testing?
Load testing is to determine if an application can work well with the heavy usage resulting from a large number of users using it simultaneously. The load is increased to simulates the peak load that the servers are going to take during maximum usage periods.
5) What are the different components of LoadRunner?
The major components of LoadRunner are:
VUGen- Records Vuser scripts that emulate the actions of real users.
Controller – Administrative center for creating, maintaining and executing load test scenarios. Assigns scenarios to Vusers and load generators, starts and stops loading tests.
Load Generator – An agent through which we can generate load
Analysis – Provides graphs and reports that summarize the system performance
6) What is the Rendezvous point?
Rendezvous point helps in emulating heavy user load (request) on the server. This instructs Vusers to act simultaneously. When the vuser reaches the Rendezvous point, it waits for all Vusers with Rendezvous point. Once designated numbers of Vusers reaches it, the Vusers are released. Function lr_rendezvous is used to create the Rendezvous point. This can be inserted by:
Rendezvous button on the floating Recording toolbar while recording.
After recording Rendezvous point is inserted through Insert> Rendezvous.
7) What are the different sections of the script? In what sequence do these sections run?
LoadRunner script has three sections vuser_init, Action and vuser_end.
vuser_init has requests/actions to login to the application/server.
Action has actual code to test the functionality of the application. This can be played many times in iterations.
Vuser_end has requests/actions to login out the application/server.
The sequence in which these sections get executed is vuser_init is at the very beginning and vuser_end at the very end. The action is executed in between the two.
8) How do you identify which protocol to use for any application?
Previously Performance tester had to depend much on the development team to know about the protocol that application is using to interact with the server. Sometimes, it also used to be speculative.
However, LoadRunner provides a great help in form of Protocol Advisor from version 9.5 onwards. Protocol advisor detects the protocols that application uses and suggest us the possible protocols in which script can be created to simulate the real user.
9) What is a correlation? Explain the difference between automatic correlation and manual correlation?
Correlation is used to handle the dynamic values in a script. The dynamic value could change for each user action (value changes when action is replayed by the same user) or for different users (value changes when action is replayed with a different user). In both, the cases correlation takes care of these values and prevents them from failing during execution.
Manual Correlation involves identifying the dynamic value, finding the first occurrence of dynamic value, identifying the unique boundaries of capturing the dynamic value, writing correlation function web_reg_save_param before the request having the first occurrence of dynamic value in its response.
Automated correlation works on predefined correlation rules. The script is played back and scanned for autocorrelation on failing. Vugen identifies the place wherever the correlation rules work and correlate the value on approval.
10) What are the Components of LoadRunner?
In load runner there are 4 components of load runner
Load Generator &
11) What is the lr_eval_string(); in loadrunner ?
lr_eval_string (); extracting the value for a given specified string.
12) What is the lr_atoi(); in loadrunner ?
lr_atoi(); extracting the value from string to integer
13) What is the lr_itoa(); in loadrunner ?
lr_itoa(); extracting the value from integer to string.
14) What is sprint(); in loadrunner ?
Storing formatted data into a file.
15) What is concat(); in loadrunner ?
Concat() in between the two string from source to destination.
Commands are as follows…. Concat (Source, Destination);
16) What is Graph merging in analysis ?
Graph merging is merging technique where we can merge in between the two graph
If y-axis from graph A is match from x-axis from B then only we can able to merged the graph The graph can be Collate graph, Auto graph, Merged graph.
17) What is 90% column in analysis ?
In 90% column is the main thing from where we can come to know the Actual Response time.
18) What is Think time in loadrunner ?
Time gap between two consecutive request is called as Thing time.
19) What is the spacing time in loadrunner ?
Time gap between two consecutive iterations.
20) What is Virtual User in controller ?
Virtual user is user who can perform the task wef, concurrent and Simultaneously & this user place an important role while test execution.
21) what are the state in Controller Vuser while performing the action ?
There are so many state are there while performing the Vuser during the load testing. Ready, Run, Init, Running, Failed, abort, gratuity.
22) What is lr_randzvous()in loadrunner ?
lr_randzvous(); is user wait time to until & unless complete the task particular user.
23) What is length() in loadrunner ?
It is used to measure the length within the specified the string.
24) What is the HTML script in load runner ?
In load runner HTML script based on resources available on the page itself. Its
25) What is the url script in load runner ?
in load runner url script is measured on the url itself
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