TestWorks Conf Performance testing made easy with gatling - Guillaume Corré

© Gatling 2015.All rights reserved.
Requirements
Background in programming
1. Object oriented language mostly
2. Functional programming is a plus, but optional
Experience
1. Gatling?
2. Scala?
1

LoadTesting Done Right
http://gatling.io
Guillaume Corré
@notdryft
2

Workshop Schedule
1. Architecture
2. Usage
3. Exercises
3

Workshop Schedule
1. Architecture
2. Usage
3. Exercises
4

Gatling:Architecture
Designed for:
1. Complex use cases
2. High Performance
3. Maintainability
5

High Performance
Optimize thread usage:
1. Non Blocking IO
2. Message oriented orchestration
6

High Performance
7

Maintainability
Code
1. Real programming language
2. DSL
3. API
8

Maintainability
Why?
1. Versioning
2. Refactoring
3. Peer review
4. Composition
9

Maintainability
10
class Simple extends Simulation {
val scn = scenario("simple")
.exec(
http("home")
.get("http://gatling.io")
.check(status.is(200)))
setUp(
scn.inject(
atOnceUsers(1)))
}

Workshop Schedule
1. Architecture
2. Usage
3. Exercises
11

Gatling: Usage
12

Usage: DSL
Extensive documentation:
http://gatling.io/#/docs
Cheat-sheet:
http://gatling.io/docs/2.1.7/cheat-sheet.html
13

Usage:Very Fast Track
Step 1: Create a Simulation class
14
import io.gatling.core.Predef._
import io.gatling.http.Predef._
import scala.concurrent.duration._
}

Step 2: Create a Scenario
15
import …
}

Step 3: Chain Actions
16
import …
.exec(
http("home")
.get("http://gatling.io"))
}

Step 4: Check your requests are fine
17
import …
.exec(
http("home")
.check(status.is(200))
}

Step 5: Set up and inject users
18
import …
.exec(
http("home")
.check(status.is(200))
setUp(scn.inject(atOnceUsers(1)))
}

Step 6: Make things dynamic
19
// Set up virtual users with feeders
feed(csv("credentials.csv"))

20
// Capture response data with checks
http("request")
.get("url")
.check(css("someSelector").saveAs("someVariable"))

21
// Craft requests with the Expression Language
http("request")
.get("/foo?bar=${someVariable}")

22
// Use functions
exec { session =>
println(session)
session
}

Expressions
23
type Expression[T] = Session => Validation[T]

Workshop Schedule
1. Architecture
2. Usage
3. Exercises
24

Workshop
4 exercises
1. Ranged from (almost) easy to difficult
2. Each pinpoint different specifics of Gatling
Url
bit.ly/gatling-workshop
Documentation reminder
http://gatling.io/#/docs
http://gatling.io/docs/2.1.7/cheat-sheet.html
25

Exercise 1:
1. First Request
What happens if you don't do any checks?
1. Gatling adds a status check by default
26

Exercise 1:
1. First Request
Are there any defaults? If so, which?
1. status.in
2. All statuses of the 20x family
3. 304
27

Exercise 1:
3. Checks
Which check should you use to fetch the title ?
1. Regex
1. Most the time harder to maintain
2. Still does the job pretty well
2. XPath
1. HTML needs to be strict and well formed
3. CSS is easy to read and fast
1. css("#logo-section a", "title")
28

Exercise 1:
3. Checks
What happens when a check matches more than a
single element?
1. exists by default
2. And, if you don’t specify a fetch method but try to save,
Gatling will add a find(0) before saveAs
29

Exercise 1:
4. Information retrieval
30
Which check should you use to fetch the menu links ?
1. css("#main-menu-inner > ul > li > a", "href")

Exercise 1:
How can you save all matches?
1. findAll
31

Exercise 1:
How can you access the “menuLinks” attribute?
1. Use the exec { session => … } syntax
2. session(“menuLinks”) for extraction
3. Then, either
1. as[Type]
2. asOption[Type]
3. validate[Type]
4. Validate recommended unless you know what you are
doing
32

Exercise 1:
4. Iterate over menu links
Which DSL element should you use?
1. foreach
2. Takes an Expression[String] as its first argument
1. Which is a function of Session toValidation[String]
3. Gatling does the EL conversion for you
33

Exercise 1:
4. Iterate over menu links
How do think it works behind the hood?
1. Iterate over each element
2. Put current element into the session as an attribute
3. Run the action block with the new session
34

Exercise 2:
1. Fetch the login page
Which baseURL should you use?
1. Gatling doesn’t add a / before concatenating
2. One of the following
1. baseURL(“https://github.com”) and get(“/login”)
2. baseURL(“https://github.com/“) and get(“login”)
3. Prefer the first one
35

Exercise 2:
1. Fetch the login page
Which check should you use?
1. The general idea is to make sure you are on the page you
requested
2. css(".auth-form form h1").is("Sign in")
36

Exercise 2:
2.1. Performing the login
Which request should you do?
1. /session
Which HTTP method does it need to use?
2. POST
37

Exercise 2:
2.2. Specifying additional parameters
Do you think these are generated or provided?
1. Generated by Github, provided in the HTML.
Where can you fetch thoses?
2. Add a check to the previous request
3. css(".auth-form form input[name='authenticity_token']",
“value").saveAs("authenticityToken")
38

Exercise 2:
3. Checks
Which checks should you use to be sure you are
logged in?
1. Check for content, titles, css, etc.
2. css(“.logged_in”)
3. exists is a default
39

Exercise 2:
4. Feeding the credentials
Which feeder file format could you use?
1. Multiple formats are handled by Gatling
1. CSV,TSV, etc.
2. Just beware of malformed files
40

Exercise 2:
4. Feeding the credentials
How does the session interact with the feeder?
1. A feeder outputs lines of CSV (and else) files into the
session
2. One line per user, with different methods of retrieval
1. Queue, failure when reading is over
2. Random
3. Shuffle, which is a shuffle + queue
4. Circular
3. If you want more, you can skip the feeding to Gatling and
fetch the records yourself
41

Exercise 3:
1. Create gist
Think of multiple ways to load the templates
1. StringBody
2. RawFileBody
3. ELFileBody, with parsed content
42

Exercise 3:
1. Create gist
Which one is better in this case?
1. All are good
2. Still, scala can handle string template pretty well
3. => StringBody
43

Exercise 4:
Part 1. 1. Start simple
Is using java.util.Random a good idea in this case?
What could happen if you do?
1. Random is synchronized
2. Multiples threads would block each other when fetching
3. ThreadLocalRandom is not
4. It creates a single Random for eachThread, resolving
conflicts
44

Exercise 4:
Part 1. 4.A twist
How does Gatling execute requests?
1. Each requests are launched in sequence
2. They cannot overlap
3. And cannot be launched asynchronously
How should we proceed instead?
45

Exercise 4:
Part 1. 4.A twist
How does Gatling execute requests?
1. Each requests are launched in sequence
2. They cannot overlap
3. And cannot be launched asynchronously
How should we proceed instead?
4. We can use the resources mechanism
5. Not its purpose, but it will work
46

Exercise 4:
Part 1I. 2. Making the queries
Is the number of tiles requested really fixed?
1. What about edges ?
2. Will reduce the number of tiles
3. We can reduce the bounds, excluding the edges
47

Exercise 4:
Mixing Gatling’s EL and Scala’s String Macro
1. This a Gatling EL:“${variableName}”
2. Theses are Scala Macros:
1. s”$variableName”
2. s”${variableName}
How?
48

Exercise 4:
Mixing Gatling’s EL and Scala’s String Macro
1. This a Gatling EL:“${variableName}”
2. Theses are Scala Macros:
1. s”$variableName”
2. s”${variableName}
How?
1. Escape Gatling’s EL when in a Scala String Macro
1. s”$${gatlingVariable}/${otherVariable}”
2. will output “${gatlingVariable}/variableContent”
49

Workshop
Solutions
1. Not available yet
Url
bit.ly/gatling-workshop-solutions
50

http://gatling.io
http://github.com/gatling/gatling
@GatlingTool

TestWorks Conf Performance testing made easy with gatling - Guillaume Corré

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