Performance Testing Interview Questions
Q) What is Performance testing?
A) Timing for both read and update transactions should be gathered to determine whether system functions are being performed in an acceptable time frame. This should be done standalone and then in a multi user environment to determine the effect of multiple transactions on the timing of a single transaction.
Q) What is Ramp up? How do you set this?
A) This option is used to gradually increase the amount of Vusers/load on the server. An initial value is set and a value to wait between intervals can be specified. To set Ramp Up, go to? Scenario Scheduling Options?
Q) Explain the following functions: –
lr_debug_message: – The lr_debug_message function sends a debug message to the output log when the specified message class is set.
lr_output_message – The lr_output_message function sends notifications to the Controller Output window and the V user log file.
lr_error_message – The lr_error_message function sends an error message to the LoadRunner Output window.
lrd_stmt – The lrd_stmt function associates a character string (usually a SQL statement) with a cursor. This function sets a SQL statement to be processed.
lrd_fetch – The lrd_fetch function fetches the next row from the result set.
Q) What does v user_init action contain?
A) V user_init action contains procedures to login to a server.
A) There are many types of V user like DB V user, SAP V user, Web V user, RTE, GUI V user.
Q) What does v user_end action contain?
A) V user_end section contains log off procedures.
Q) What is V user Generator?
A) There are two methods – GET & POST.
Q) What is Think Time?
A) it is used for making the v-users wait for some time between the requests in order to simulate as if the real users are using the server.
Q) What is the Transaction?
A) To measures the performance of the server, we define the Transaction.
Q) What?s the Rendezvous Point?
A) We can insert Rendezvous Points into V user script to emulates the heavy load on the server.
Q) What?s the V user Inuit Section?
A) In V user In it section, LoadRunner records log in the server.
Q) What are the section contain by the VuGen while creating a V user script?
A) VuGen contain the three section-
* V user In it Section
* Action Section
* V user end Section
Q) How do you edit the script?
A) We can edit the script by inserting the Transaction Points and Rendezvous? Points.
Q) What?s the running V user graph?
A) It displays the number of V users that execute the V user script each seconds of scenario run.
Q) What?s the percentile graph?
A) It displays the percentage of transaction which were performed with in given time.
Q) What does Result window contain?
A) Result Window open with two panes-
* Tree Pane
* Summary Pane
Q) How many types of Correlation?
A) Correlation are two types-
* Manual Correlation
* Automatic Correlation
Q) What is Automatic Correlation?
A) Automatic Correlation is set some rules for correlation.
Q) Where do you set automatic correlation options?
A) Automatic correlation from web point of view can be set in recording options and correlation tab. Here we can enable correlation for the entire script and choose either issue online messages or offline actions, where we can define rules for that correlation. Automatic correlation for database can be done using show output window and scan for correlation and picking the correlate query tab and choose which query value we want to correlate. If we know the specific value to be correlated, we just do create correlation for the value and specify how the value to be created.
Q) Which Correlation function you have used?
Q) What is the syntax for think time?
Q) What is the Elapsed Time?
A) It is total time take since request is set and obtained the result.
Q) What is a scenario?
A) A scenario defines the events that occur during each testing session. For example, a scenario defines and controls the number of users to emulate, the actions to be performed, and the machines on which the virtual users run their emulations.
Q) If you want to stop the execution of your script on error, how do you do that?
A) The lr_abort function aborts the execution of a Vuser script. It instructs the Vuser to stop executing the Actions section, execute the vuser_end section and end the execution. This function is useful when you need to manually abort a script execution as a result of a specific error condition. When you end a script using this function, the Vuser is assigned the status “Stopped”. For this to take effect, we have to first uncheck the? Continue on error? Option in Run-Time Settings.
Q) What is Scenario Wizard?
A) We can create new scenario through Scenario Wizard.
Q) If web server, database and Network are all fine where could be the problem?
A) The problem could be in the system itself or in the application server or in the code written for the application.
Q) What is Rendezvous graph?
A) It displays that when V users released from rendezvous point and how many V users released from each point.
Q) What is Correlation?
A) Correlation is used to obtained the data which are unique in every time of script run and which are generated by nested queries.
Q) What is the relation between Response Time and Throughput?
A) The Throughput graph shows the amount of data in bytes that the V users received from the server in a second. When we compare this with the transaction response time, we will notice that as throughput decreased, the response time also decreased. Similarly, the peak throughput and highest response time would occur approximately at the same time.
Q) What is think time? How do you change the threshold?
A) Think time is the time that a real user waits between actions. Example: When a user receives data from a server, the user may wait several seconds to review the data before responding. This delay is known as the think time. Changing the Threshold: Threshold level is the level below which the recorded think time will be ignored. The default value is five (5) seconds. We can change the think time threshold in the Recording options of the Vugen.
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