Hello,
looking for interview questions in loadrunner? I have tried my level
best to put these interview questions. If you find any new questions, you can
always send me through the contact form below. I will include them in
this list. Never give up in the interview. If you fail in one
interview try for another interview, try and try until you get success. If you
need any help you can always contact me through the contact form below. I will
reply as soon as possible. All the best for your interview!!!!
I
have categorized the loadrunner interview questions and
answers into 5 parts:
Performance
Testing
Loadrunner General
Questions
Vugen and
Scripting
Controller
Analysis
Performance Testing
Interview Questions And Answers:
What
is Performance Testing?
Performance
Testing on a software application is done to determine how
speed, stability and scalability the application is. Speed refers to how fast
the software application will respond, and stability refers to how the
application handles varying workloads. Scalability is the total amount of
workload the software application can handle.
What
is Load Testing?
It
is done to understand how varying expected loads would make the system behave.
For instance, its behavior if they were many users concurrently using the same
application to carry out critical transactions for a certain period of time. It
is able to give the application's response time for all the important
transactions in a business. Load testing can be done for
a business's database and servers which will be very helpful in
identifying any existent bottlenecks.
What
is Stress Testing?
This
is done to determine whether the software application can still perform well
even in cases of extreme load. It helps the application administrators know to
what extent the application can be stretched without creating bottlenecks.
What
is Soak Testing?
Soak
testing monitors the system's performance over time. It is also referred to as
endurance testing. It aims at determining the system's capability to sustain
the normal load over time. The test involves looking out for potential leaks by
monitoring memory utilization, as well as performance degradation. Performance
degradation refers to the system's response time over a prolonged period of
sustained use. Does it remain constant, improve or
decline? Results of this test are derived from application of
a significant amount of load to the system for a particular period of time.
What
is Spike Testing?
This
test involves a sudden increase in the amount of load, for instance a sudden
increase in the number of users making transactions using the application. It
is meant to determine whether the system will crash, slow down or whether it
will be able to handle the surge.
What
is Isolation Testing?
This
is usually a repeat of the test execution that had caused a problem in the
system. It is done to confirm the domain in which the fault had occurred.
What
is Volume Testing?
It
is a non-functional test. A certain amount of data is used to test the software
application. The data can be a database or an interface file like .dat
or. xml. To volume test the database, expand it to the desired size and
then test the application for it. If you need the application to interact with
a specific interface file, get a sample of the size you desire and then run the
application.
What
is Failover Testing?
Failover
testing is done in order to determine if a server fails during the heavy load:
Is load balancer able to react quickly and is able to drive the traffic to
another web server/application server. Is the other web server/application
server able to handle the unexpected load. This test helps to determine how the
server behaves during these type of scenarios.
Explain
the performance test life cycle that you follow?
Gathering
the requirements from client
Understanding
the architecture/environment of the application
Planning
and Designing the tests
Preparing
and enhancing the scripts
Executing
the tests in controller
Analyzing
the results
Fine
tuning the application
Retesting
the application after fine tuning the application and repeat this process until
we meet the SLA (Not 100% up to 90% at least).
What
are all the requirements you gather from your client for performance testing?
The
architecture of the application and the technologies used to develop the
application?
What
is a web server, application server and database server?
What
are the browsers and Java versions supported by the application?
What
are the different load balance techniques used?
What
are the protocols used between client and server? Ex: HTTP, HTTPS,
FTP etc.
What
are the Business scenarios we need to test?
What
are the preferred tools for performance testing and monitoring? Ex:
Loadrunner, Jmeter, Sitescope and Wily Introscope.
What
is the workload model and identifying the workload model?
SLA
of the application in terms of response times and hardware resource utilization.
Have
you prepared Test Plan/Test Strategy?
Yes.
What are the contents in your Test Plan/Test Strategy?
It's always
better to go through the test plan before the interview, it helps a lot.
Some of the Test Strategy contents are Introduction, Purpose of The
Document, Scope Of The Document, Application Architecture And Topology,
Performance Testing Requirements And Dependencies, Objectives And Goals Of
Performance Testing, Scope Of Performance Testing, In Scope, Out Of Scope,
Application Performance Scenarios, Workload Characteristics, Application
Test Environment, Performance Test Tools, Performance Test Dependencies,
Hardware Dependency, Software Dependency etc.
What
is little’s law?
Tell
me some of the performance testing tools that you use in your company?
Loadrunner, Jmeter, Sitescope, HP Diagnostics, Wily Introscope, Dynatrace and Java Profiler.
What
is performance tuning?
Performance
tuning is done during the process of performance testing. Issues will be identified
during the different types of performance testing. Performance tuning will be
done based on the issues. It might be a software /
hardware tuning. Usually Bottlenecks are identified in application
and database servers. Proper tuning of the servers, code and SQL queries
resolves the issue. Sometimes changes in the hardware resources will
also help.
What is the
difference type of tests you conducted during testing?
Load Testing, Stress Testing, Failover Testing etc.
Loadrunner General Questions:
What
is Loadrunner?
Loadrunner is a performance testing tool. It is developed by Mercury and acquired HP. It has versions Loadrunner 7 to Loadrunner 12.
What
are the Loadrunner components?
Vugen, Controller, Load Generators, Analysis, Shunra.
What
are the Loadrunner versions used?
Loadrunner 9.52, Loadrunner 11.3, and Loadrunner 11.5 and Loadrunner 11.52.
Vugen And
Scripting Questions:
How
do you start the script?
We usually start the scripting after understanding of Business Critical Scenarios.
What
are the various functions you have used while creating the scripts?
You should able to tell at least 10 loadrunner functions and different functions that you have used in different protocols.
What
is Step download timeout error?
If the application does not respond in 120 seconds, step download timeout occurs in loadrunner. We can increase the step download timeout error in Loadrunner (Runtime Settings -> Preferences -> Options -> General -> Step Download Timeout.
What
are the different type of parameters available?
Custom,
Date/Time,File, Group Name, Iternation Number, Load Generator Name, Random
Number, Table, Unique Number, User Defined Function and Vuser ID.
What
is advanced trace?
It
logs all the vuser messages and function calls.
What
are the Logs available in LR?
Code
Generation, Replay Log
What
are the protocols you worked on?
Tell the protocols that you know and explain how good you are in that protocols.
Difference
between Think Time & Pacing?
Think
is time interval between two transactions.
Pacing
is the time interval between two iterations.
What
is Parameterization & Correlation?
Parameterization
is giving the input through a parameter file in loadrunner.
Correlation
capturing a required value from the server response in loadrunner. Example:
SessionID.
How
do you run specific part of your script for a specified number of times?
We can run the specific part of the script by using blocks in run time settings -> General -> Run Logic.
What
are different recording modes available in LR?
We have mainly two recording modes HTML mode and URL mode.
What
are the advanced features of URL recording mode in LR 9.5?
We
have mainly two features:
Create
concurrent groups for resources after their source HTML page.
Use
web_custom_request only.
What
is the difference between resource=0 and resource=1?
Here www.msn.com Resource is 0
as it is the main URL and the corresponding resources like image resource is 1.
What
is the difference between lr_abort and lr_exit?
Lr_abort: it stops the
execution of the action part and executed the vuser_end section.
Lr_exit: it exits from
the particular action, script or iteration and there are different options with
lr_exit;
Example:
lr_exit
(LR_EXIT_VUSER, LR_FAIL);
lr_exit
(LR_EXIT_ACTION_AND_CONTINUE, LR_FAIL);
What
is the difference between lr_eval_string and lr_save_string?
Lr_eval_string:
It extracts a value from a given parameter.
Lr_save_string:
It saves c variable into loadrunner variable.
What
is context less and context based?
Context
less mean the request does not depend on the previous request. Context based
means the request is dependent on the previous request.
What
is the use of Save Count in web_reg_find?
Number
of times the given text has found in a particular page.
What
is Correlation and its function with attributes?
Capturing a value from the server response. The function name is web_reg_save_param. List of attributes are Step Name, ParameterName, LeftBoundary, RightBoundary, ORD, NotFound = Warning/Error, Savelen, Saveoffset.
How
do you do auto correlation?
From Loadrunner 11.5 we have a beautiful option called Design Studio. The loadrunner will detect the dynamic values and we can do the correlation easily.
If source is not available, then how do you do correlation?
We have different option to do correlation, Generation Log, Replay Log.
Difference
between “Save Offset” & “ Save Length” and what are test flags?
Save offset is used to ignore the number of letters and Save Length is used to save the length of the parameter.
When
do you use Web_Custom_request?
The name of the function itself indicates the custom request. Web_custom_request is the last option that vugen prefer during creation of the script. It first tries to create the script using different web functions. This function is used by the vugen when it cannot interpret the requests with the other web functions.
Dynamically the post data is changing, what do you do?
In this situation, I will use web_custom_request and use the for loop to append the dynamically changing data to web_custom_request.
What
are check point available in LR?
web_find, web_reg_find, web_image_check.
Do
you write any user defined functions?
Make sure you prepare well for this question.
What
are the run time settings you have used in your script?
We use the run time settings based on our requirements. Iteration, Run Logic, pacing thinktime etc.
What
are the challenges you have faced during script generation & execution?
Prepare well for this question, you should be able to answer the question clearly.
What is the difference between get and post request?
Get
Request
|
Post
Request
|
We can use
up to 2048 character length.
|
It has no
restrictions
|
Get request
is less secure.
|
Post request
is secure.
|
It can be
cached
|
It cannot be
cached.
|
It can be
bookmarked
|
It can not
be bookmarked.
|
What
is the difference between web_url and web_link?
web_url:
It's
a GET request
The
web_url function does not require a context
web_url
is recorded only when VuGen is in either URL–based recording or in HTML–based
recording mode.
web_link:
web_link
function is an action function that emulates a mouse click on the link that is
defined by the attributes.
The
web_link function can be executed only in the context of a previous operation.
web_link
is recorded only when VuGen is in HTML-based recording mode.
What
is the difference between web_submit_data and web_submit_form?
Web_submit_form
|
Web_submit_data
|
It is a
context based submission
|
It is a
context less submission
|
It is
recorded only html based
|
It is
recorded both in html and url mode.
|
What
is the difference between web_submit_data and web_custom_request?
Web_submit_data
|
Web_custom_request
|
It is a
context less submission
|
It is also
context less submission.
|
We cannot
write a custom request.
|
We can write
a custom request using this function.
|
We can send
through get or post request
|
We can send
only post request
|
What
is the difference between web_find and web_reg_find?
Web_find
deprecated and we have only web_reg_find now.
What
is the difference between lr_output_message and lr_error_message?
Lr_output_message
|
Lr_error_message
|
The lr_output_message sends
message to the output window, log files (such as the Vaughan log file and the
Application Management Web site and agent log file), and other test report
summaries. When a script is run in VuGen, the output file is output.txt.
|
The lr_error_message function
sends an error message to product output windows (such as the LoadRunner
output window), log files (such as Vugen and the Application Management agent
log file), and other test report summaries. For details regarding the output
for each product, see the product's user guides.
|
If Run-time
settings > General > Miscellaneous > Fail open transactions on
lr_error_message is selected, calling lr_error_message will
fail the transaction in addition to sending the message
|
|
To send a
message to the output file, you must enable logging in the run-time settings,
and select Always send messages. If you select Send
messages only when an error occurs, there is no output from this
function.
|
VuGen
displays the message text of the lr_error_message function
in the Execution log in red, using Error code 17999. Note that this function
sends a message to the output even when logging is disabled in the run-time
settings.
|
Controller And Analysis
Interview Questions And Answers:
Difference
between Scenario & Group, Real world Schedule & Basic Schedule?
Difference between Performance Center & Controller?
HP Loadrunner
|
HP
Performance Center
|
It is a
standalone application
|
It is a web
based application.
|
Only single
load test is executed at a time.
|
Here we can
execute multiple load tests.
|
We cannot
trace the requirements and defects
|
Here we can
trace the requirements and defects
|
We cannot
reserve time slots for machines
|
Here we can
use timeslots to reserve the machines
|
Loadrunner is
good if we are using from one location.
|
Performance
Center is good if we are operating from different locations.
|
How
do you come to know which Vuser failed?
We
can check in the vuser status message.
What
is Rendezvous point?
When
lr_rendezvous function is called, all the users wait at that point and executes
the next step.
What
is IP Spoofer in loadrunner?
We can create the IP addresses dynamically using IP Spoofer.
Can
you configure load generators in Windows & Unix?
Yes, we can configure the load generators in both Windows and Unix.
Can
we run different scripts by using Performance Center and the Controller?
Yes, we can run.
Analysis
What
are the default counters that loadrunner analysis file shows?
Vusers,
Hits Per Second, Throughput, Average Transaction Response Time, Transactions
per second.
What
are the Operating Systems counters you monitor?
CPU, Memory, Disk, Network
Give
me 5 server counters that you regularly check?
Response
times, throughput, hits per second, CPU, Memory, Heap Memory.
What
AWR Reports? From which version of the Oracle – AWR feature is added?
AWR
stands for Automatic workload Repository. It is introduced from Oracle 10g.
What
is Granularity?
Granularity is the time interval of sampling the data in loadrunner analysis.
Difference between Thread & Process?
Thread
|
Process
|
Threads are
dependent on each other in a process
|
Process are
independent of each other
|
Threads uses
very less resources
|
Process uses
very high resources
|
Threads
shares the address space
|
Process
requires a separate address space
|
Threads
carry very less information when compared with process.
|
Process
carry more information
|
What
is JVM & Unix?
JVM
stands for Java Virtual Machine which is a platform independent and converts
Java byte code to machine language. As it is platform independent we can
execute the code on any operating systems.
Unix
is a multiuser operating system and has many flavors like Linux, Sun Solaris,
AIX, HP Unix, Ubuntu etc.
What
is Memory Leakage?
What
is Garbage Collection?
What
are the algorithms available in GC?
What
is Heap memory?
How
do you monitor server counters?
We use Sitescope or NMON tool and different commands available in Linux VMSTAT, IOSTAT, TOP etc.
What
is Table Scanning?
When
there are no Proper indexes given in the database tables, some queries will
scan the entire data in the tables and collect the results which will increase
the response time.
What
are context switches?
What
is a deadlock?
Deadlock
occurs when two or more processes/threads waiting for the other to finish and
it never happens and this leads to deadlock. This situation will apply to
hardware/software, Java and databases.
What
do you suggest to your client if there is a sudden hike in the CPU utilization
while execution?
Sudden
hike in the CPU utilization might have many reasons. We need to analyze what
caused the high CPU utilization by using different tools and profilers.
What
is Parsing, Soft Parse, and Hard Parse?
Parsing: It will check
the syntax, misspelled SQL keywords and authentication.
Soft
Parse:
If the requested query is found in shared pool soft parsing occurs and it
consumes less resources.
Hard
Parse:
If the requested query is not found in shared pool hard parsing occurs
and it consumes very high resources.
What
is the difference between Web Server, Application Server and Database Server?
Web Server
|
Application
Server
|
Database
Server
|
Ex: Apache,
IIS and Nginx
|
Weblogic and
Websphere
|
Oracle, My
SQL, and SQL server
|
It handles
HTTP requests.
|
It handles
HTTP requests and it contains business logic.
|
It handles
different queries, and records.
|
Resource
utilization is low.
|
Resource
utilization is high.
|
Resource
utilization is high.
|
What
is standard deviation in loadrunner?
Standard
deviation in loadrunner is done with the total response times of a particular
transaction.
For
example, if you ran a transaction for 10 iterations. It will take the 10
transaction response times and calculates the Standard Deviation. If the standard
deviation between these 10 values is high. Then it is a bottleneck, it should
always low.
Examples:
Response
times for login page with 5 iterations ->1, 1, 1, 1, 1=Standard Deviation is
0
Response
times for a logout page with 5 iterations 1, 2, 3, 4, 5, 6=Standard Deviation
is 2.5 which is high.
Is
there any impact if we reduce “Think Time” up to 50%?
Yes,
there will be impact as the load on the server increases if we decrease think
time. Mainly we have an impact on response times, throughput and system
resources etc.
How
to check network bandwidth is not sufficient?
Data
Transfer rate between application server and database server or between client
and the server is more than the bandwidth, then we can conclude the bandwidth
is not sufficient.
Weblogic
Top Counters for Performance Testing:
Thread
Pool, DB Connection Pool, Garbage Collection, Java Heap memory, Load Balancing,
Application logs, Hard Page Faults.
Oracle
DBA Top Counters for Performance Testing:
In
AWR Report: Shared Pool Memory, Cache Hit Ratios, Top 5 Events, Top SQL by CPU,
Top SQL by I/O, Top wait events, Buffer pool cache hit ratios.
Operating
System Counters are common for both Weblogic and
Oracle DBA: CPU, Memory, Disk I/O, and Network.
At Last......
Every
option in the Vugen, Controller and Analysis are important. The interviewer
might ask any question on the tool. We should prepare for the interview in such
a manner. Please go through the following settings once before you go for
the interview.
Run
time settings
Recording
Options
Controller
Options
The
main challenge in the interview will be questions on Analysis. You should
prepare well for these topics in order to crack the interview.