scrum hates technical debt

CSM v9.3 © Jeff Sutherland 1993-2008; © Joe Little 2010

SCRUM HATES TECHNICAL DEBT

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© Joe Little 2010

Joe Little

• Agile Coach & Trainer• 20+ years in senior level consulting to well-known firms in New York, London and

Charlotte• Focus on delivery of Business Value; interest in Lean • CST, CSP, CSM; MBA• Was Senior Manager in Big 6 consulting• Head of Kitty Hawk Consulting, Inc. since 1991• Head of LeanAgileTraining.com• Started trying to do [Agile] before reading The Mythical Man-Month

– http://agileconsortium.blogspot.com

– [email protected]

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© Joe Little 2010

Customers want a quality product quickly.

Is this a problem?

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© Joe Little 2010

What is technical debt?

It helps to have a fairly common definition.

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© Joe Little 2010

Agenda

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What is technical debt - done?How would you notice it?"Scrum made me go too fast!" NO!!!The bad news does not get better with ageWhy Scrum hates Technical DebtThe importance of a definition of done in ScrumA velocity that is based on a weak definition of done is just a lie!!!How do we explain technical debt to the product owner?

© Joe Little 20106

How do we explain technical debt to the managers?The importance of professionalism in ScrumWhy is Scrum only a framework?Scrum assumes your engineering practices are not "perfect"Some engineering practices (mostly from XP)

Incentives

Did I mention? Scrum hates Technical Debt!

© Joe Little 2010

How do you notice Technical Debt?

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© Joe Little 2010

Is Technical Debt bad?

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Scrum Dynamic Model

Value Velocity

Daily Meeting

READY

DONE

IMPEDIMENTS

Sprint

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© Joe Little 2010

My opinion: Technical Debt is bad. Period. Very bad!

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© Joe Little 201011

“Scrum made us go too fast!”

No!

© Joe Little 2010

A velocity that allows technical debt to be built is a lie!

A velocity that is built on a weak definition of done is a lie!

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Definition of Done needed to split stories Default Definition of Done

• Automated tests, built & run• No bugs• Acceptance tested• Release notes written• Releasable• No increased technical debt

Default Definition of Done• Unit/Integration tested• Accepted by PO• Ready for acceptance test• Deployed on demo server = I haven’t made

the codebase hard to change

Default Definition of Done• Releasable

What’s NOT included in DoD? - Example: ”customer acceptance test + user documentation”?Why not? Who does it? When? What happens if a problem turns up?

Source: Henrik Kniberg13


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The bad news does not get better with age.

!"#$%&'#()(!*+$#,#*"%-(Time cost of defects for you?

0

5

10

15

20

25

30

35

40

45

50

10 minutes 1 hour Same Day Next Day 1 Week 2 weeks 1 month 2 months

Relative Cost of defects if fixed later


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We have to slow downto go fast.


Knowledge decays fast

Don’t let any bugs escape the Sprint

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Why Scrum hates Technical Debt

It’s a bad life for youHateful workBad reputationYou know it’s sinful!

The customers hate it (ultimately, at least)The business guys go nuts!

It seems to make Scrum look bad (not really true, but appearances sometimes count)

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XP

CompanyC

LeanAgile

Scrum

CompanyB Company

C

CompanyA

Queue theory

Game theory

History

Research

Philosophy

Topic: Explaining to Product Owner

Chaos theory Principles

Practices

Implementation

More theory...

Source: Henrik Kniberg

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Clean & simple

Henrik Kniberg

public class Dog { private final String name; private int woofCount = 0;

public Dog(String name) { this.name = name; }

public void woof() { ++woofCount; }}

import java.sql.Connection;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;

public class Dog {private Executor executor = Executors.newFixedThreadPool(18);private int CACHE_SIZE = 50;

public Dog() {try { Class.forName("oracle.jdbc.ThinDriver"); connection = DriverManager.getConnection("jdbc:oracle:thin:@prod", "admin", "beefhead"); statement = connection.prepareStatement("insert into Dog values (?, ?, ?)"); } catch (ClassNotFoundException e) {}

new Thread().start();}

public void woof(Person woofCaller) {Connection connection = null;PreparedStatement statement = null;try { connection = DriverManager.getConnection("jdbc:oracle:thin:@prod", "admin", "beefhead"); statement = connection.prepareStatement("insert into Dog values (?, ?, ?)"); statement.setLong(1, System.currentTimeMillis()); statement.setString(2, person.getName()); statement.setString(3, person.getPhoneNumber().getNumber()); statement.executeUpdate(); } }}} Connection a = DriverManager.getConnection("jdbc:oracle:thin:@prod", "admin", "beefhead");b = a.prepareStatement("select * from Dog where name = '" + name + "'"); c = b.executeQuery();if (c.next()) {String foundName = c.getString("name"); PhoneNumber phoneNumber = new PhoneNumber(c.getString(“woofCount")); Person person = new Person(foundName, phoneNumber);return person;} else { return new Person("", null);}

} catch (SQLException e) { return null;} catch (IllegalArgumentException x) { throw x; }}

public List<Person> getAll() { connection = DriverManager.getConnection("jdbc:oracle:thin:@prod", "admin", "beefhead"); statement = connection.prepareStatement("insert into Dog values (?, ?, ?)"); statement.setLong(1, System.currentTimeMillis());}if (statement != null) {if (c.next()) {String foundName = c.getString("name"); PhoneNumber phoneNumber = new PhoneNumber(c.getString(“woofCount")); Person person = new Person(foundName, phoneNumber);return person;} else {

Dog.java v0Dog.java v1.1Big & hairy

Dog.java v1.2Clean & simple

public class Dog { public static void main(String[] args) { System.out.println("WOOF 1!"); System.out.println("WOOF 2!"); }}

Dog.java v1.0Quick & dirty

Simple code:1.Passes all tests2.No duplication3.Readable4.Minimal

Simple is hard!

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Velocity calibration


EstimatedVelocity

ActualVelocity

40 30

30 28

30 31

30 30

Estimated Actual

40 30

40 30

40 30

Estimated Actual

40 30

50 30

60 30

Estimated Actual

40 35

35 30

30 25

30

25

20

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Technical debt & release planning

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Remainingstory points

Sprint2 3 4 5 6 7 8 9 10 11 12 13 14 15

100

200

300

400

Um... we’re donewhen we’re done!

We’ll be done by sprint 10!

Sorry, we’re late!We should definitely by done by sprint 12!


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3 roles• Product owner• Scrum master• Team

3 artifacts• Product backlog• Sprint backlog• Sprint burndown

4 activities• Sprint planning• Daily scrum• Sprint review• Retrospective


Technical debt

Vmax

Vactual

velo

city

time

Vmax

velo

city

time

VactualSustainable pace!

Definition of Done• .... bla bla ....• No increased technical debtCode duplication

Test coverageCode readability


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Definition of Done• .... bla bla ....• Technical debt decreased


3 roles• Product owner• Scrum master• Team

3 artifacts• Product backlog• Sprint backlog• Sprint burndown

4 activities• Sprint planning• Daily scrum• Sprint review• Retrospective

Dealing with technical debt

Vmax

Vactua

l

velo

city

time

Road to hell

First stepSlow downStop accumulating debt

Second step(optional)Slow down even moreStart repaying debt

Sustainable pace Increasing pace!

Definition of Done• .... bla bla ....• No increased technical debt


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© Joe Little 2010

The bad news does not get better with age!!!

We have to go slow to go fast.

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© Joe Little 2010

To the Product Owner

Was that enough?What would you add?

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© Joe Little 2010

How do we explain Technical Debt to the manager?

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© Joe Little 2010

Manager

Protection from magical-thinking managers: Velocity!

Explaining Sustainable Pace

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The importance of a definition of done.

We recommend a detailed Definition of Done, that is clear about how we will not build technical debt.


The importance of professionalism

Scrum is not an excuse to be un-professional. Quite the contrary.

Why is Scrum only a framework?

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Coaching: Technical debt & Scrum.

Engineering practicesImprovementsIncentives

Key Engineering Practices

Which ones??

Key Engineering Practices

...pair programming

...TDD

...continuous integration

...refactoring, refactoring, refactoring

...10 minute build

...automatic unit tests

...automated functional tests (other names)

...automated other testing (regression especially)

How do we give the team the proper incentives?

(Or avoid the wrong incentives??)

What do we measure to assure proper incentives?

* We focus on speed and low work-in-process.* We see the impediments better.* We fix the root causes.* Over time, this enables everything: cheaper, higher quality, faster, more what they want.

The End

Please send me your comments and suggestions. This is an important topic. If it were easy, we as an industry would not have this problem. So, I appreciate your

feedback.

[email protected]://leanagiletraining.com

scrum hates technical debt

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