Load runner-Questions and Answers- What is load testing? - Load testing is to test that if the
application works fine with the loads that result from large number of
simultaneous users, transactions and to determine weather it can handle
peak usage periods.
- What is Performance testing?
- Timing for both read and
update transactions should be gathered to determine whether system
functions are being performed in an acceptable timeframe. 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.
- Did u use LoadRunner? What version?
- Yes. Version 7.2.
- Explain the Load testing process?-
Step 1: Planning the test. Here, we develop a clearly defined test plan to ensure the test scenarios we develop will accomplish load-testing objectives. Step 2: Creating Vusers. Here,
we create Vuser scripts that contain tasks performed by each Vuser,
tasks performed by Vusers as a whole, and tasks measured as
transactions. Step 3: Creating the scenario. A scenario
describes the events that occur during a testing session. It includes a
list of machines, scripts, and Vusers that run during the scenario. We
create scenarios using LoadRunner Controller. We can create manual
scenarios as well as goal-oriented scenarios. In manual scenarios, we
define the number of Vusers, the load generator machines, and
percentage of Vusers to be assigned to each script. For web tests, we
may create a goal-oriented scenario where we define the goal that our
test has to achieve. LoadRunner automatically builds a scenario for us. Step 4: Running the scenario.
We emulate load on the server by instructing multiple Vusers to
perform tasks simultaneously. Before the testing, we set the scenario
configuration and scheduling. We can run the entire scenario, Vuser
groups, or individual Vusers. Step 5: Monitoring the scenario.
We monitor scenario execution using the LoadRunner online runtime,
transaction, system resource, Web resource, Web server resource, Web
application server resource, database server resource, network delay,
streaming media resource, firewall server resource, ERP server
resource, and Java performance monitors. Step 6: Analyzing test results. During
scenario execution, LoadRunner records the performance of the
application under different loads. We use LoadRunner’s graphs and
reports to analyze the application’s performance.
- 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.
- How do you find out where correlation is required? Give few examples from your projects?
- Two ways: First we can scan for correlations, and see the list of values which can be correlated.
From this we can pick a value to be correlated. Secondly, we can record
two scripts and compare them. We can look up the difference file to see
for the values which needed to be correlated. In my project, there was
a unique id developed for each customer, it was nothing but Insurance
Number, it was generated automatically and it was sequential and this
value was unique. I had to correlate this value, in order to avoid
errors while running my script. I did using scan for correlation.
- What are the components of LoadRunner?
- The components of
LoadRunner are The Virtual User Generator, Controller, and the Agent
process, LoadRunner Analysis and Monitoring, LoadRunner Books Online.
- What Component of LoadRunner would you use to record a Script?
- The Virtual User Generator (VuGen) component is used to record a
script. It enables you to develop Vuser scripts for a variety of
application types and communication protocols.
- What Component of LoadRunner would you use to play Back the script in multi user mode?
- The Controller component is used to playback the script in multi-user
mode. This is done during a scenario run where a vuser script is
executed by a number of vusers in a group.
- Where do you set automatic correlation options?
- 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.
- What is a function to capture dynamic values in the web Vuser script?
- Web_reg_save_param function saves dynamic data information to a parameter.
- When do you disable log in Virtual User Generator, When do you choose standard and extended logs?
- Once we debug our script and verify that it is functional, we can
enable logging for errors only. When we add a script to a scenario,
logging is automatically disabled. Standard Log Option: When you select
Standard log, it creates a
standard log of functions and messages sent during script execution to
use for debugging. Disable this option for large load testing
scenarios. When you copy a script to a scenario, logging is
automatically disabled Extended Log Option: Select
extended log to create an
extended log, including warnings and other messages. Disable this
option for large load testing scenarios. When you copy a script to a
scenario, logging is automatically disabled. We can specify which
additional information should be added to the extended log using the
Extended log options.
- How do you debug 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.
- How do you write user defined functions in LR? Give me few functions you wrote in your previous project?
- Before we create the User Defined functions we need to create the external
library (DLL) with the function. We add this library to VuGen bin
directory. Once the library is added then we assign user defined
function as a parameter. The function should have the following format:
__declspec (dllexport) char* <function name>(char*,
char*)Examples of user defined functions are as follows:GetVersion,
GetCurrentTime, GetPltform are some of the user defined functions used
in my earlier project.
- What is a rendezvous point?
- You insert rendezvous points into Vuser scripts to emulate heavy user load on the server. Rendezvous points instruct
Vusers to wait during test execution for multiple Vusers to arrive at a
certain point, in order that they may simultaneously perform a task.
For example, to emulate peak load on the bank server, you can insert a
rendezvous point instructing 100 Vusers to deposit cash into their
accounts at the same time.
- What is a scenario?
- 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.
- Explain the recording mode for web Vuser script?
- We use
VuGen to develop a Vuser script by recording a user performing typical
business processes on a client application. VuGen creates the script by
recording the activity between the client and the server. For example,
in web based applications, VuGen monitors the client end of the
database and traces all the requests sent to, and received from, the
database server. We use VuGen to: Monitor the communication between the
application and the server; Generate the required function calls; and
Insert the generated function calls into a Vuser script.
- Why do you create parameters?
- Parameters are like script
variables. They are used to vary input to the server and to emulate
real users. Different sets of data are sent to the server each time the
script is run. Better simulate the usage model for more accurate
testing from the Controller; one script can emulate many different
users on the system.
- What is correlation? Explain the difference between automatic correlation and manual correlation?
- Correlation is used to obtain data which are unique for each run of
the script and which are generated by nested queries. Correlation
provides the value to avoid errors arising out of duplicate values and
also optimizing the code (to avoid nested queries). Automatic
correlation is where we set some rules for correlation. It can be
application server specific. Here values are replaced by data which are
created by these rules. In manual correlation, the value we want to
correlate is scanned and create correlation is used to correlate. - What are the changes you can make in run-time settings?
- The Run Time Settings that we make are: a) Pacing - It has iteration count. b) Log - Under this we have Disable Logging Standard Log and c) Extended Think Time - In think time we have two options like Ignore think time and Replay think time. d) General - Under general tab we can set the vusers as process or as multithreading and whether each step as a transaction.
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