Load testing is to test that if the application works well with the loads from large number of simultaneous
users and transactions. It also used to determine whether it can handle peak usage periods.

Load Runner is a performance testing tool from HP. This tool supports all aspects such as Load, Stress,
Endurance, data volume and spike Testing.

Following are the components of LoadRunner

• The Virtual User Generator
• Controller, and the Agent process
• LoadRunner Analysis and Monitoring
• LoadRunner Books Online

The Virtual User Generator (VuGen) component is used to record a script and it enables you to develop Vuser
scripts for a variety of application types and communication protocols.

Rendezvous points are introduced into Vuser scripts to simulate more users on the server. Rendezvous points
instruct Vusers to wait during test execution in order to perform the tasks simultaneously.

For example, in a banking application, Rendezvous points are inserted for 100+ multiple users to deposit
money simultaneously.

A scenario is nothing but an event that occurs for each testing session.

For example, a scenario defines

Number of users

Action to be performed

VuGen contains two options to debug Vuser scripts

• Run Step by Step command and
• Breakpoints.

We can also manually set the message class within your script using the lr_set_debug_message function.

Functionality under load can be tested by running several Vusers concurrently. By increasing the Vusers, it
is necessary to determine how much load the server can sustain.

The Throughput shows the amount of data in bytes that the Vusers received from the server in a second.
When It is compared with transaction response time, throughput and response time get decreased. The
peak throughput and highest response time would occur approximately at the same time.

Vuser_init action contains procedures to login to a server and Vuser_end section contains log off
procedures.

The standard log sends a subset of functions and messages to the output log and subset of functions
depends on the Vuser type.

Extended log sends a detailed script execution messages to the output log. It is mainly used during
debugging when user needs information about Parameter substitution.

Load Runner provides you with five different types of goals:

Number of concurrent Vusers

Number of hits per second

Number of transactions per second

Number of pages per minute

Transaction response time

Web_reg_save_param is the function that saves dynamic data information to a parameter.

Following are the testing process in LoadRunner:

Plan load test

Create Vuser Scripts

Define Scenario

Run Scenario

Analyze results

The remote command launcher enables the controller to start applications in the host machine.

Vuser scripts can be developed either by recording with the load vuser script generator or by using Load
runner vuser script template.

While running the scenario, loadrunner controller instructs the remote agent dispatcher to launch
loadrunner agent. The controller instructs the loadrunner agent to initialize, run, pause and stop the vusers.

Hits per second means the number of hits the server receives in one second from the vuser.

Request per second is the number of request the vuser will request from the server.

Following are the advantages of Load Runner:

• Reduces human intervention
• Reduces the requirement of the systems
• Helps in the better usage of time and money
• Effective utilization of automation
• Single point execution

The vuser is the virtual users who can simulate the real users. The virtual users who take the place of real
users’s operating client software, such as IE sending requests using the HTTP protocol to IIS or Apache
web servers.

Use should create the external library that contains the function. This library must then be added to the bin
directory of VuGen. And then, the user-defined function can be assigned as a parameter.

There are four run-time settings that can be made:

• Pacing: This contains iteration count.
• Log: Logging can be set to standard or disabled.
• Think Time: Capable of setting think time to be ignored or replayed.
• General: Allows the setting of Vusers for processes or multithreading.

Monitors and the Data Resource Graph can be used to find database related issues. LoadRunner allow the
tester to specify the resource that needs to be measured before the controller is run.

There are 5 types of graphs:

• Network delay time graph – displays the time that elapses between request and response
• Two transaction response time graphs – one transation response time graph for load and another one for

percentile

• Hits/second graph – Shows application traffic volume
• Pages download/second graph – shows the rate at which pages are downloaded per second

Monitors can be used to detect performance bottlenecks. These include network, web server, application
server, and database server monitors.

These monitors can be used to locate trouble spots in scenarios that cause increase in response time and
throughput, network delays, performance response time, hits/second, etc.

Ramp up is gradually increasing the load on a server and can be simulated by gradually increasing the
number of Vusers. This feature can be found in the Scenario Scheduling Options.

Correlation can be performed in two ways:

• Use the scan function to search for correlations and select a value from the result.
• Record a pair of scripts and then compare them to each other.

The automatic correlation is set in recording options area on the correlation tab. Correlation can be enabled
for the full script and rules for correlation can be defined.

Automatic correlation can be performed on a database by viewing the output window, scanning for
correlation, and selecting the value that will be used.

The advantage of running a Vuser script as a thread which allows more Vusers to be used for one load
generator. Running Vuser scripts as processes utilizes a lot of memory because all of the loaded scripts use
the same driver.

This limits the number of Vuser scripts that can be run on one generator.

Overlay Graph:

Overlay graph has one X axis and 2 Y-axis. Left Y-axis on the merged graph shows the current graph’s
value & Right Y-axis show the value of Y-axis of the graph that was merged.

Correlate Graph:

There are two graphs and the active graph’s Y-axis becomes X-axis of merged graph. Y-axis of the graph
that was merged becomes merged graph’s Y-axis.

Following are the three sections of Vuser script and they are as follows:

• Vuser_init - Used for recording the logon.
• Actions - Used for recording the business process.
• Vuser_end - Used for recording the logoff.

Following are the four selection methods:

• Sequential
• Random
• Unique
• Parameter name

Parameter substitution can be viewed in the extended log in the Run time settings.

Following tools are required to analyze Vuser run results:

Execution Log

Run-Time Viewer and

Mercury Test Results window

Server resources monitor is used to find how much data is coming from Cache and helps to find out what
are all the parts of the system have bottlenecks.

'Show Browse'’ setting is used to see the pages that appear during playback. This is useful for debugging
Vuser during the initial stages of Web Vuser creation.

Continue on should be set only when making Execution Logs more descriptive or adding logic to the
Vuser.

The purpose of a Load Runner transaction is to measure one or more steps/user actions of a business
process.

Parameters are like script variables and they are used to vary input to the server to emulate real users.

• Different sets of data are sent to the server whenever the script is run.
• Better simulate the usage model for more accurate testing from the Controller and one
• script can emulate many different users on the system.

The lr_output_message is a function that sends notifications to the Controller Output window and to the
Vuser log file.

The problem could be in the system itself or in the application server or in the code written for the
application.

LoadRunner script code is obtained by recording in the ANSI C language syntax and it can be viewed in
the script view.

Performance testing can be done by calculating the timing for both read and update transactions and check
whether system functions are being performed in an acceptable timeframe. In a multi user environment, it
is necessary to determine the effect of multiple transactions on the timing of a single transaction.

The configuration of systems refers to that of the client machines in which we will run Vusers. The
configuration of client machine includes its hardware settings, memory, operating system, software
applications, development tools, etc.

This system component configuration should match with the overall system configuration so as to achieve
the load testing objectives.

The lr_abort function is used to abort 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.

Think time is the time where a real user waits between actions.

When a user receives data from a server or other applications, the user may wait several seconds to review
the data before responding. This time delay is called as think time.

Protocol is used in Load Runner to interact with the application.

As of 20-Feb-2013 Load Runner 11.5 is the latest version and VUser script is used like a C Language.

Following languages are supported by LoadRunner:

1. C Language

2. Visual Basic Scripting

3. Visual Basic For Applications

4. Java Scripting

Following are the protocols that Load Runner can support are:

• .NET Record / Display
• Database
• DCOM
• Network
• Oracle E-Business
• SAP
• SOA
• Web and Multimedia
• Wireless
• JOBSMATE.COM
• GUI
• Java Record and replay
• Remote desktop
• Web 2.0

• Vuser generator - For generating Scripts
• Controller - For creating and executing scenarios
• Analyzer - To analyze results

Agent is interface between host machine and controller

The possible issues amongst others could be -

1. Lack of Hardware

2. Memory Leakage

3. Network related issues.

4. Application/Software error