Performance and load testing

Part 1

Performance & Load Testing Basics

Performance & Load Testing Basics

 Introduction to Performance Testing
 Difference between Performance, Load and
Stress Testing
 Why Performance Testing?
 When is it required?
 What should be tested?
 Performance Testing Process
 Load Test configuration for a web system
 Practice Questions

Introduction to Performance Testing

 Performance testing is the process of determining the speed or
effectiveness of a computer, network, software program or
device.

 Before going into the details, we should understand the factors
that governs Performance testing:

 Throughput
 Response Time
 Tuning
 Benchmarking

Throughput
 Capability of a product to
handle multiple transactions
in a give period.

 Throughput represents the
number of
requests/business
transactions processed by
the product in a specified
time duration.

 As the number of concurrent
users increase, the
throughput increases almost
linearly with the number of
requests. As there is very
little congestion within the
Application Server system
queues.

Throughput

 In the heavy load zone or Section B, as the concurrent client
load increases, throughput remains relatively constant.

 In Section C (the buckle zone) one or more of the system
components have become exhausted and throughput starts to
degrade. For example, the system might enter the buckle zone
when the network connections at the Web server exhaust the
limits of the network adapter or if the requests exceed operating
system limits for file handles.

Response Time

 It is equally important to find
out how much time each of
the transactions took to
complete.

 Response time is defined as
the delay between the point
of request and the first
response from the product.

 The response time increases
proportionally to the user
load.

Tuning

 Tuning is the procedure by
which product performance
is enhanced by setting
different values to the
parameters of the product,
operating system and other
components.

 Tuning improves the product
performance without having
to touch the source code of
the product.

Benchmarking

 A very well-improved
performance of a product
makes no business sense if
that performance does not
match up to the competitive
products.

 A careful analysis is needed
to chalk out the list of
transactions to be compared
across products so that an
apple-apple comparison
becomes possible.

Performance Testing- Definition

 The testing to evaluate the response time (speed), throughput
and utilization of system to execute its required functions in
comparison with different versions of the same product or a
different competitive product is called Performance Testing.

 Performance testing is done to derive benchmark numbers for
the system.

 Heavy load is not applied to the system

 Tuning is performed until the system under test achieves the
expected levels of performance.

Difference between
Performance, Load and Stress Testing

Load Testing
 Process of exercising the
system under test by feeding it
the largest tasks it can operate
with.
 Constantly increasing the load
on the system via automated
tools to simulate real time
scenario with virtual users.

Examples:
 Testing a word processor by
editing a very large document.
 For Web Application load is
defined in terms of concurrent
users or HTTP connections.

Difference between
Performance, Load and Stress Testing

Stress Testing
 Trying to break the system under
test by overwhelming its
resources or by taking resources
away from it.
 Purpose is to make sure that the
system fails and recovers
gracefully.

Example:
 Double the baseline number for
concurrent users/HTTP
connections.
 Randomly shut down and restart
ports on the network
switches/routers that connects
servers.

Why Performance Testing?

 The week of Feb 6, 2000:
Hackers delivered over 1-Billion transactions concurrently to
each one of these sites.
 Yahoo
 eBay
 Buy.com
 Amazon
 eTrade

How did you think they performed ?

Why Performance Testing

 Identifies problems early on before they become costly to
resolve.
 Reduces development cycles.
 Produces better quality, more scalable code.
 Prevents revenue and credibility loss due to poor Web site
performance.
 Enables intelligent planning for future expansion.
 To ensure that the system meets performance expectations such
as response time, throughput etc. under given levels of load.
 Expose bugs that do not surface in cursory testing, such as
memory management bugs, memory leaks, buffer overflows, etc.

When is it required?

Design Phase:

Pages containing lots of images and multimedia for reasonable
wait times. Heavy loads are less important than knowing which
types of content cause slowdowns.

Development Phase:

To check results of individual pages and processes, looking for
breaking points, unnecessary code and bottlenecks.

Deployment Phase:

To identify the minimum hardware and software requirements
for the application.

What should be tested?
 High frequency transactions: The most frequently used
transactions have the potential to impact the performance of all
of the other transactions if they are not efficient.

 Mission Critical transactions: The more important
transactions that facilitate the core objectives of the system
should be included, as failure under load of these transactions
has, by definition, the greatest impact.

 Read Transactions: At least one READ ONLY transaction
should be included, so that performance of such transactions
can be differentiated from other more complex transactions.

 Update Transactions: At least one update transaction should
be included so that performance of such transactions can be
differentiated from other transactions.

1.Planning
1.Planning

 Determine the performance testing objectives

 Describe the application to test using a application model

1. Describe the Hardware environment

2. Create a Benchmark (Agenda) to be recorded in Phase 2.

A. Define what tasks each user will perform
B. Define (or estimate) the percentage of users per task.

1.Planning
1.Planning 2.Record
2.Record 3.Modify
3.Modify

Record
 Record the defined testing activities that will be used as a
foundation for your load test scripts.
 One activity per task or multiple activities depending on
user task definition

Modify
 Modify load test scripts defined by recorder to reflect more
realistic Load test simulations.
 Defining the project, users
 Randomize parameters (Data, times, environment)
 Randomize user activities that occur during the load test

4. Execute
4. Execute

Virtual Users (VUs): Test Goals
Start: 5 Max Response Time <= 20 Sec
Incremented by: 5
Maximum: 200
Think Time: 5 sec

Test Script:
One typical user from login through completion.

5.Monitor
5.Monitor 6. Analyze
6. Analyze

 Monitoring the scenario: We monitor scenario execution using
the various online runtime monitors.

 Analysing test results: During scenario execution, the tool
records the performance of the application under different loads.
We use the graphs and reports to analyse the application’s
performance.

Load Test configuration for a web system

Questions to Review your Skills

 What are the factors that governs Performance Testing?
 How are Throughput and Response time related with user load?
 How do we decide whether the application passed or failed the
load test?
 What do you mean by Capacity, Stability and Scalability of an
application.
 What is the difference between Performance, Load and Stress
testing?
 What is Longevity, endurance, spike and Volume Testing?
 At what point in SDLC, performance testing is required?
 How to identify the transactions in a complete application for
load testing?
 Define the 6 steps involved in Performance Testing Process?
 Explain the Load Test configuration of a web system and what is
the role of Load Generators in it?

Load Test Planning

 Why Planning
 Analysing the Application
 Defining Testing Objectives
 Gathering Requirements
 Load Test Checklist

Why Planning
 As in any type of system testing, a well-defined test plan is the
first essential step to successful testing.

Planning load testing helps to:
 Build test scenarios that accurately emulate your working
environment: Load testing means testing the application
under typical working conditions, and checking for system
performance, reliability, capacity, and so forth.
 Understand which resources are required for testing:
Application testing requires hardware, software, and human
resources. Before beginning testing, we should know which
resources are available and decide how to use them effectively.
 Define success criteria in measurable terms: Focused
testing goals and test criteria ensure successful testing. For
example, it’s not enough to define vague objectives like “Check
server response time under heavy load.” A more focused
success criterion would be “Check that 50 customers can
check their account balance simultaneously & that server
response time will not exceed 1- minute”

Why Planning

 Load test planning is a three-step process:

 Analyzing the Application
• Analysis ensures that the testing environment we create
using LoadRunner will accurately reflect the environment
and configuration of the application under test.

 Defining Testing Objectives
• Before testing, we should define exactly what we want to
accomplish.

 Gathering Requirements
• All the requirements and resources should be evaluated
and collected beforehand to avoid any last minute
hurdles.

Analyzing the Application

 Load testing does not require as much knowledge of the
application as functional testing does.

 Load tester should have some operational knowledge of the
application to be tested.

 Load tester should have the idea on how the application is
actually used in production to make an informed estimate.

 Load tester must know the application architecture (Client
Server, Local Deployment, Live URL), Platform and Database
used.

Defining Testing Objectives

 Determining and recording performance testing objectives
involves communicating with the team to establish and update
these objectives as the project advances through milestones

 Performance, Load or Stress testing: Type and scope of
testing should be clear as each type of testing has different
requirements.

 Goal Setting: General load testing objectives should be defined.


 Common Objectives:
 Measuring end-user response time

 Defining optimal hardware configuration

 Checking reliability

 Assist the development team in determining the performance
characteristics for various configuration options
 Ensure that the new production hardware is no slower than
the previous release
 Provide input data for scalability and capacity-planning
efforts
 Determine if the application is ready for deployment to
production
 Detect bottlenecks to be tuned


Stating Objectives in Measurable Terms:
 Once you decide on your general load testing objectives, you
should identify more focused goals by stating your objectives in
measurable terms.
 To provide a baseline for evaluation, determine exactly what
constitutes acceptable and unacceptable test results.
 For example:

 General Objective:

• Product Evaluation: choose hardware for the Web server.

 Focused Objective:

• Product Evaluation: run the same group of 300 virtual
users on two different servers, HP and NEC. When all
300 users simultaneously browse the pages of your Web
application, determine which hardware gives a better
response time.

Gathering Requirements
Users: Identify all the types of people and processes that can put
load on the application or system.
 Defining the types of primary end users of the application or
system such as purchasers, claims processors, and sales
reps
 Add other types of users such as system administrators,
managers, and report readers who use the application or
system but are not the primary users.
 Add types of non-human users such as batch processes,
system backups, bulk data loads and anything else that may
add load or consume system resources.
Transactions: For each type of user we identified in the previous
step, identify the tasks that the user performs.
Production Environment:
 Performance and capacity of an application is significantly
affected by the hardware and software components on which
it executes.

Production Environment:
 Speed, capacity, IP address and name, version numbers and
other significant information.
Test Environment:
 Should be similar to the production environment as is
possible to be able to get meaningful performance results.
 It is important that the databases be set up with the same
amount of data in the same proportions as the production
environment as that can substantially affect the
performance.
Scenarios:
 Select the use cases to include

 Determine how many instances of each use case will run
concurrently
 Determine how often the use cases will execute per hour

 Select the test environment


Load test Tool:
 Ability to parameterize data.

 Ability to capture dynamic data and use on subsequent
requests.
 Application infrastructure monitoring.

 Support for the application's protocols

Load test Lab must include the following:
 Test Servers.

 Databases.

 Network elements, operating systems and clients and server
hardware.

Load Test Check List
Planning
 Objective goals defined

 Test plan written and reviewed

Staff Skills
 Experience in load testing

 Application knowledge

 Systems knowledge

 Communication and people skills

Support Staff
 Key staff identified and allocated

Load Test Lab
 Test servers allocated

 Databases populated

 Load test tools allocated


 Why planning is required before starting load test?
 What are the three steps involved in load test planning?
 What information should be collected about the application to
be load tested?
 What are the common testing objectives?
 State the following testing objective in measurable term:
“Ensure that the new production hardware is not slower than
the previous release”
 Why is the knowledge of Production Environment necessary
before load test?
 What are the factors that need to be considered for creating a
scenario?
 How to choose a load test tool?
 What are the requirements to setup a load test lab?
 What are main points in a Load test checklist?

Load Testing Tools

 Manual testing Limitations
 Benefits of Automation
 Tools used for Performance Testing

Manual Testing Limitations
Do you have the testing resources?
All of you, • Testing personnel
click the • Client machines
GO button
again How do you coordinate and synchronize users?
How do you collect and analyze results?
How do you achieve test repeatability?

Coordinator

Analysis? Web server Database
Testers 123.20
server

Load Generation System Under Test


 Expensive, requiring large amounts of both personnel and
machinery.
 Complicated, especially co-ordinating and synchronising
multiple testers
 Involves a high degree of organization, especially to record and
analyse results meaningfully
 Repeatability of the manual tests is limited

Benefits of Automation
Solves the resource limitations
• Replaces testers with virtual users
Analysis • Runs many Vusers on a few machines
• Controller manages the virtual users
Controller • Analyze results with graphs and
reports

Vuser Web server Database
server
host

Load Generation System Under Test

Benefits of Automation

Using Automated Tools
 Reduces personnel requirements by replacing human users with
virtual users or Vusers. These Vusers emulate the behaviour of
real users
 Because numerous Vusers can run on a single computer, the
tool reduces the amount of hardware required for testing.
 Monitors the application performance online, enabling you to
fine-tune your system during test execution.
 It automatically records the performance of the application
during a test. You can choose from a wide variety of graphs and
reports to view the performance data.
 Because the tests are fully automated, you can easily repeat
them as often as you need.

Tools used for Performance Testing

Open Source Commercial
 OpenSTA  LoadRunner
 Diesel Test  Silk Performer
 TestMaker  Qengine
 Grinder  Empirix e-Load
 LoadSim

 Jmeter

 Rubis

OpenSTA

 Developed in C++
 HTTP Load Test Application

Advantages:
 Open Source Software

 A user-friendly graphical interface

 The script capture from the browser

 The monitoring functionality

Drawbacks:
 Only designed for Windows

 Only for HTTP

DieselTest
 Software designed in Delphi5
 For systems under NT Environment
 For HTTP/HTTPS applications

Advantages:
 Open Source
 The quality of the chart
 Simple and fast to use
 The logging functionality

Drawbacks:
 The manual edition of the tests is badly designed
 The ambiguity of certain results
 Distributed tests are impossible
 Specific technology environment (Delphi, NT)

TestMaker
 Developed in Java
 For HTTP, HTTPS, SOAP, XML-RPC, Mails (SMTP, POP3 and
IMAP) applications

Advantages:
 The possibility to build any kind of test agent

 The power of Java programming with some Python
simplifications
 Open source

Drawbacks:
 Familiarity with the Jython scripting language, Java language
and to write it from scratch
 The monitoring tools are very basic, since it is limited to the
response analysis
 Must pay for distributed testing

Grinder
 Generic framework for load testing any kind of target systems,
with scenario in Jython
 Developed in Java

Advantages:
 Open Source

 You can test everything with scripts in Jython

Drawbacks:
 Deployment for distributed test

 Poor results and graphical interface

LoadSim
 LoadSim is an open source software developed in Java, which is
designed for HTTP distributed load testing

Advantages:
 Open Source

 Generation of script

 Each client have a different configuration (user, script…)

Drawbacks:
 No graphical interface

 Poor results

 No graphical representation of result

 No monitoring

Jmeter
 100% Java desktop application
 For Web and FTP, Java, SOAP/XML-RPC, JDBC applications

Advantages:
 Open Source
 The distributed testing
 Various target systems
 Extensibility: Pluggable samplers allow unlimited testing
capabilities

Drawbacks:
 Chart representation quite confuse
 Terminology not very clear
 Necessary to start remote machine one by one
 Remote machines must be declared in a property file before
starting application

Rubis

 Provided with some load-test tool (designed for Rubis, but some
parts of code could be re-used) and a monitoring system.
 Developed in Java.

Advantages:
 Open Source

 Monitoring capabilities

 Charts representations and automatic generation of HTML
report

Drawbacks:
 Specific to Unix environment and Rubis application

Empirix eLoad

 Accurate testing of the response times and scalability of web
applications and web services
 Recording in VBscript

Advantages:
 Can simulate hundreds and thousands of concurrent users

 Monitoring capabilities and Charts representation

 Reasonable Price

Drawbacks:
 Complex User Interface

 Limitations in recording of complex scenarios


 What are the limitations of manual load testing?
 Why tools are used for automating load test?
 List 5 Open Source and 5 Commercial load test tools.
 What are the disadvantages of LoadRunner?
 Explain the following Load Test tools: Silk Performer, Qengine.
 Give a detailed comparison between Empirix E-load and
LoadRunner.
 Which other tools are commonly used for load testing?

Thank You

Created By BALKRISHNA

Performance and load testing

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