impa

ct

www. l

oadi

mpa

ct.c

omLoad

Outline• What is load impact?

• The main Components of Load Impact.o Load testing tool.

o Page analyzer.

• Why Load Test?

• What is a test configuration?

• How to create test configuration?

• What is Scheduled tests?

• How to schedule tests?

• Using page analyzer.

• What is user scenarios?

• How to create your own scenarios?

• How to create user scenarios?o Lua Tutorial.

o Load impact with scripting?

o HTTP status codes.

What is load impact?

• Load Impact is a cloud-based service for load

testing and website optimization. It generates

traffic load by simulating users. Load Impact is a

so-called freemium service.

The main Components of Load Impact

• Load Impact consists of two main

parts:1. Load testing tool.

2. Page analyzer.

1. Load testing tool

• It generates simulated user traffic to a website. Users can

simulate virtual users who are trying to load the web pages

at the same time.

• Results are displayed in real time throughout the test

process.

• There are three different types of load test:

1. Fixed - Test with static load level throughout the test.

2. Ramp-up - Test that starts at a low level and increases stepwise until it

reaches a maximum predetermined level.

3. Timeout - Ramp-up tests that increase the load level until the server

becomes too slow, or when the maximum load level is reached.

2. Page analyzer

• It loads a web page the same way a web browser

would.

• It shows the user what objects were loaded, in

what order, and how long each object took to load.

• It also gives the user information about return

codes, compression ratio, etc.

Why Load Test?

• Having a fast website is a key to commercial success on the

Internet.

• A slow website will increase your bounce rate, reduce your

rank in search engines & reduce conversions rates.

• In studies published in says that the average visitor expects a

web page to load in no more than two seconds.

• In 2010, Google has included site speed as part of its search

ranking algorithm.

What is a test configuration?

• A test configuration describes the load test you want to run

– how many simulated users the test should load your site

with, and what those users should do on your site (what

pages they should load on the site).

How to create test configuration?

1

2

1- choose the “test configuration” section, then click on “Create test configuration”.2- Type a name for the test, then enter the target URL

How to create test configuration? (CONT>>)

3

This section will allow

you to specify what

load levels the test will

use, and how quickly to

ramp up or down

to/from those load

levels.

How to create test configuration? (CONT>>)

3

What are VU and SBU users?

• A Virtual User will only use a single network

connection when loading resources from a target

host. Resources can be loaded from multiple hosts in

the same test, however, that will then result in one

connection per target host, per VU.

• A Simulated Browser User (SBU) can use multiple

concurrent network connections when loading

resources from a single target host. This results in

faster page loads, but also a lot more stress on the

target server that has to serve four connections at

once instead of just one.

How to create test configuration? (CONT>>)

4

4 – Add extra IP address! But why?

Let’s take this example “If you are running a 800 SBU test with

user scenarios distributed evenly across a total of 5 loadzones (i.e.

800/5 = 160 SBUs per loadzone), you will have 1 (IP addresses

assigned for 160 SBUs per loadzone) x 5 (user scenarios/loadzones)

= 5 IP addresses assigned to your load test”.

How to create test configuration? (CONT>>)

5

5 – Finally, click on “Create test configuration and start

test” to start testing.

Or, you could click on, “Create test configuration” to save

the configuration for later use.

What is Scheduled tests?Scheduling allows you to run a load test at some point in the

future, or to run a load test regularly at certain intervals.

How to schedule tests?

11- choose the “Scheduled tests” section, then click on “Add new scheduled test”.

How to schedule tests? (CONT>>)

2

“Make sure you have created test configuration” before you start scheduling.

2- choose the test configuration.

3- Type the schedule data.

4- Type the schedule time.

5- choose the reputation time

(Daily, Weakly, Monthly).

6 – Schedule it.

3

4

56

Using page analyzer• To Access the page analyzer section

go to: https://loadimpact.com/page-analyzer

1- Type the target URL.

2- choose the browser to emulate during analysis.

3- click on analyze.

1 2 3

Case Study: ksu.edu.sa

The load times are

represented as colored

bars which is divided into

several components. They

are:

- Time in queue (grey).

- DNS lookup time

(orange).

- Connection time

(yellow).

- Time to first byte

(green).

- Download time (blue).

Case Study: ksu.edu.sa (CONT>>)

What is user scenarios?

A user scenario is a sequence of HTTP transactions that emulates a

certain type of user on your site. You can have several user

scenarios in a single load test, emulating several different types of

users.

What is Lua?

Lua is a lightweight multi-paradigm programming language

designed as a scripting language.

Why Lua?

• Lua is cross-platform.

• It’s simple, elegant and easy to learn.

• It’s also light-weight and very suitable for resource-intensive

applications such as load testing.

A Quick tutorial: Introduction to

let’sog

Types in LuaThere are 8 types in Lua:

1- Number : Numeric value represented in double.

2- String: A sequence of arbitrary characters.

3- Boolean : "true" and "false“.

4- function : First-class object in Lua.

5- Table : Heterogeneous[1] hash table.

6- Thread : C data structures defined by C users.

7 – Userdata : Lua coroutine, a cooperative threading.

8- Nil : Nothing.

[1] : Heterogeneous composed of parts of different kinds.

Functions in Lua

function foo(a, b, c)  local sum = a + b  return sum, c  --A function can return multi values.

End

var1, var2 = foo(1, '123', ‘KSU')  --Parallel assignmentprint(var1, var2)

output:

124 KSU

Tables in Lua

To create Table:> t = {} -- construct an empty table and assign it to variable "t" > print(t)

Output: table: 0035AE18

Tables as arrays:> t = { 1,1,2,3,5,8,13 } > print( t[1] )

Output: 1 > print( t[0] )

Output: nil > print( t[4] )

Output: 3

What about this: > = # t --

Output: 7guess what?To find the size of the table

:)

How to create your own scenarios?Scenario name

TargetURL

Generate the scenario automatically

Validate script

docu

men

tation

Editor

Validation results

How to create your own scenarios?Examples:1- load test a single recourse

http.request_batch({ {"GET", http://loadimpact.com/"}

})

2- POST requestshttp.request_batch({

{"POST", "http://test.loadimpact.com/login.php" , data="login=test_user&password=123"}

})

3-  Load-test multiple resourceshttp.request_batch({ {“GET”, “http://test.loadimpact.com/news.php”}}) http.request_batch({

{“GET”, “http://test.loadimpact.com/contacts.php”}})

How to create your own scenarios?(CONT>>)

Examples:4- Random delays between requests

http.request_batch({ {"GET", "http://test.loadimpact.com/news.php"}, }) client.sleep( math.random(1, 15) --Sleeps between 1 - 15 seconds before continuing ) http.request_batch({ {"GET", "http://test.loadimpact.com/news.php"}, })

5- Read HTTP headers from a response local response = http.request_batch({ {"GET", "http://google.com"}, }) log.info( "google.com uses `" .. tostring(response[1].headers["Server"][1])

.. "' as a server software" )

How to create your own scenarios?(CONT>>)

Examples:

6- Setting headers for a request Sometimes you need to set custom HTTP headers for your request. One

reason is to see if your server handles client-side caching.

local response = http.request_batch({ {"GET", "http://test.loadimpact.com/", headers = { ["If-Modified-Since"] = "Tue, 18 Jun 2013 03:30:00 GMT"; } } }) if response[1].status_code==304 then log.info("not modified") elseif response[1].status_code==200 then log.info("modified") else log.error("unexpected code" .. tostring(response[1].status_code)) end

Some HTTP status codes:Categories: 1xx Informational , 2xx Success , 3xx Redirection , 4xx Client Error , 5xx Server Error.

Status code Description

304 Not ModifiedIndicates that the resource has not been modified since the version specified by the request headers If-Modified-Since or If-Match.

400 Bad RequestThe request cannot be fulfilled due to bad syntax.

401 UnauthorizedSimilar to 403 Forbidden, but specifically for use when authentication is required and has failed or has not yet been provided.

403 ForbiddenThe request was a valid request, but the server is refusing to respond to it.

404 Not FoundThe requested resource could not be found but may be available again in the future

500 Internal Server Error

A generic error message, given when no more specific message is suitable.

503 Service Unavailable

The server is currently unavailable (because it is overloaded or down for maintenance).

The End

For more information

Visit the knowledge base

http://support.loadimpact.com/

References

• https://loadimpact.com/learning-center/

• http://support.loadimpact.com/knowledgebase/articles/

• http://en.wikipedia.org/wiki/List_of_HTTP_status_codes

• http://www.lua.org/pil/contents.html

?

This file is licensed under a Creative Commons Attribution