XP2017 - Feature Branching is Evil

Feature branching is one of the most commonly accepted practices in the IT industry. It is mainly used to control quality and to control feature delivery. However, many times the inverse is true. Branches break the flow of the IT delivery process, reducing both stability and throughput. Unfortunately, oftentimes teams are not aware of this. They truly think they are doing the right thing.

The session explores why teams are using feature branches, what problems are introduced by using them and what techniques exist to avoid them altogether. It explores exactly what's evil about feature branches, which is not necessarily the problems they introduce - but rather, the real reasons why teams are using them.

After the session, you'll understand a different branching strategy, how it relates to Continuous Integration and how it will predict better quality and higher delivery throughput.

Learning outcomes - you will be able to:

- understand why teams are using feature branching
- explain why feature branching is problematic
- describe alternatives to feature branching
- run an experiment with trunk-based development

Transcript

1. @tdpauw @tdpauw@mastodon.social thinkinglabs.io @tdpauw @tdpauw@mastodon.social thinkinglabs.io Feature Branching is Evil Tenderhearted Thierry takes questions at the end of the session Ghent, Belgium On the left, Korenlei On the right, Graslei
2. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Being vulnerable … I’m shy and introverted
3. @tdpauw @tdpauw@mastodon.social thinkinglabs.io A tale of 2 teams
4. @tdpauw @tdpauw@mastodon.social thinkinglabs.io “Like all powerful tools, there are many ways you can use them (DVCS), and not all of them are good.” -- On DVCS, continuous integration, and feature branches, Jez Humble
5. @tdpauw @tdpauw@mastodon.social thinkinglabs.io -- 2016 State of DevOps Report
6. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Some definitions ...
7. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Mainline is the line of development which is the reference from which the builds of your system are created that feed into your deployment pipeline. -- Jez Humble
8. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Feature Branching is a practice where people do not merge their code into mainline until the feature they are working on is "done" (but not “done done”). -- Jez Humble
9. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Continuous Integration is a practice where members of a team integrate their work frequently - usually each person integrates at least daily - leading to multiple integrations per day. Each integration is verified by an automated build […]. -- Martin Fowler
10. @tdpauw @tdpauw@mastodon.social thinkinglabs.io The goal of an Organisation is to sustainably minimise the lead time to create positive business impact.
11. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Why feature branching?
12. @tdpauw @tdpauw@mastodon.social thinkinglabs.io It allows us to work in isolation. Therefore we are more productive.
13. @tdpauw @tdpauw@mastodon.social thinkinglabs.io "Developing in isolation can help an individual go faster but it does not help a team go faster. Merge time and rework cannot be estimated and will vary wildly, and the team can only go as fast as the slowest merge." -- Steve Smith
14. @tdpauw @tdpauw@mastodon.social thinkinglabs.io If a refactoring goes nowhere we can just delete it.
15. @tdpauw @tdpauw@mastodon.social thinkinglabs.io “A spike solution is a very simple program to explore potential solutions. Build the spike to only address the problem under examination and ignore all other concerns. Most spikes are not good enough to keep, so expect to throw it away.” -- extremeprogramming.org, Don Wells
16. @tdpauw @tdpauw@mastodon.social thinkinglabs.io It allows us to control the quality of what goes into production.
17. @tdpauw @tdpauw@mastodon.social thinkinglabs.io "The objective is to eliminate unfit release candidates as early in the process as we can ... You are effectively prevented from releasing into production builds that are not thoroughly tested and found to be fit for their intended purpose." -- Continuous Delivery, Jez Humble and Dave Farley
18. @tdpauw @tdpauw@mastodon.social thinkinglabs.io It allows us to control which features get into production.
19. @tdpauw @tdpauw@mastodon.social thinkinglabs.io "Feature Branching is a poor man's modular architecture, instead of building systems with the ability to easy swap in and out features at runtime/deploy-time they couple themselves to the source control providing this mechanism through manual merging." -- Dan Bodart
20. @tdpauw @tdpauw@mastodon.social thinkinglabs.io What are the a problems?
21. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Feature Branching delays feedback. => Continuous Isolation
22. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Feature Branching hinders integration of features. Promiscuous Integration ???
23. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Feature Branching hides work for the rest of the team. frequently merging back to mainline = communicating with your team
24. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Feature Branching works against refactoring.
25. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Feature Branching creates inventory. inventory = money stuck in the system
26. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Feature Branching increases risk.
27. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Feature Branching creates cognitive overload.
28. @tdpauw @tdpauw@mastodon.social thinkinglabs.io How to avoid?
29. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Continuous Integration Your application is always in a releasable state on main line. Trunk Based Development
30. @tdpauw @tdpauw@mastodon.social thinkinglabs.io always commit on Green. decoupled code base. lots of fast tests. Break large changes into a set of small incremental changes.
31. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Hide unfinished new functionality.
32. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Use Expand-Contract when performing large refactorings.
33. @tdpauw @tdpauw@mastodon.social thinkinglabs.io
34. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Feature Toggles to decouple feature release from code deployment.
35. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Feature Toggles done badly are evil too !
36. @tdpauw @tdpauw@mastodon.social thinkinglabs.io A frequently asked question
37. @tdpauw @tdpauw@mastodon.social thinkinglabs.io When mature enough no Code Reviews. Pair Programming => Continuous Code Review post-commit review • pre-merge: short lived branches + Pull Request How to perform Code Reviews ? • post-merge: Non-Blocking Code Reviews
38. @tdpauw @tdpauw@mastodon.social thinkinglabs.io The Benefits …
39. @tdpauw @tdpauw@mastodon.social thinkinglabs.io => more frequent builds => more frequent deployments => reduced Time to Market => more experiments => uncover more unmet needs More frequent commits to mainline
40. @tdpauw @tdpauw@mastodon.social thinkinglabs.io => uncovers more problems earlier => fix problems immediately => build quality in => better Stability & Quality More frequent builds
41. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Where is the evilness ?
42. @tdpauw @tdpauw@mastodon.social thinkinglabs.io … and slow builds
43. @tdpauw @tdpauw@mastodon.social thinkinglabs.io "Trunk-based development requires a big mindset shift. Engineers thought trunk-based development would never work, but once they started, they could not imagine ever going back." -- Gary Gruver, Directory of Engineering for HP's LaserJet Firmware division
44. @tdpauw @tdpauw@mastodon.social thinkinglabs.io @tdpauw @tdpauw@mastodon.social thinkinglabs.io Ghent, Belgium On the left, Korenlei On the right, Graslei Hello, I am Thierry de Pauw Article series: https://thinkinglabs.io/on-the-evilness-of-feature-branching is chief imposter enjoys dark chocolate, coffee and whisky dark means > 50% cacao, prefers 70% and more
45. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Resources SCM Patterns (ch 4 Mainline; ch 5 Active Development Line), Stephen Berczuk and Brad Appleton Growing Object Oriented Software guided by Tests, p172 Keyhole Surgery for Software, Steve Freeman and Nat Pryce Continuous Delivery (ch 14 Advanced Version Control), Jez Humble and Dave Farley The Role of Continuous Delivery in IT and Organizational Performance, Nicole Forsgren and Jez Humble The State of DevOps Report 2016, Alanna Brown, Nicole Forsgren, Jez Humble, Nigel Kersten and Gene Kim DevOps Handbook (ch 11 Enable and Practice CI), Gene Kim, Jez Humble, Patrick Debois and John Willis Accelerate (ch 4 Technical Practices), Nicole Forsgren, Jez Humbe and Gene Kim Measuring Continuous Delivery (ch 7 The Mainline Throughput indicator), Steve Smith trunkbaseddevelopment.com ThoughtWorks Technology Radar on GitFlow Continuous Integration on a dollar a day, James Shore On DVCS, Continuous Delivery and Feature Branches, Jez Humble Why software development methodologies suck, Jez Humble
46. @tdpauw @tdpauw@mastodon.social thinkinglabs.io More Resources Don't Feature Branch, Dave Farley Feature Branch, Martin Fowler Version Control Stragies series, Steve Smith More Feature Branches means less Continuous Integration, InfoQ interview with Steve Smith The Death of Continuous Integration, Steve Smith Long-Running Branches Considered Harmfull, Jade Rubick An e-mail conversation with Steve Smith on Trunk Based Development Continuous Isolation, Paul Hammant What is Trunk Based Development ?, Paul Hammant Trunk Based Development, Jon Arild Tørresdal You Are What You Eat, Dave Hounslow Google's Scaled Trunk Based Development, Paul Hammant Legacy App Rejuvenation, Paul Hammant Why Google Stores Billions of Lines of Code in a Single Repository ?, Google
47. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Even More Resources The history of “Taking Baby Steps”, Adrian Bolboaca Baby Steps TDD approach, David Völkel 4 Simple Tricks to avoid Merge Conflicts, Robert Mißbach From GitFlow to Trunk Based Development, Robert Mißbach Short-lived branches, Corey Haines Introducing Branch by Abstraction, Paul Hammant Branch by Abstraction, Martin Fowler Make Large Scale Changes Incrementally with Branch by Abstraction, Jez Humble branchbyabstraction.com Feature Toggles, Pete Hodgson #NoStaging - Pipeline Conf 2016, Dave Nolan When Feature Flags go Wrong, Edith Harbaugh Managing Feature Flag Debt with Split, Adil Aijaz
48. @tdpauw @tdpauw@mastodon.social thinkinglabs.io Yet More Resources Continuous Delivery and Code Review from the Continuous Delivery Google Group Theory X and Theory Y from Wikipedia Continuous Review, Paul Hammant Non-Continuous Review, Paul Hammant Code Review: Why are we doing it ?, Sandro Mancuso Code Reviews in Trunk Based Development, Robert Mißbach A conversation in the SoCraTes Slack #codereview channel on … Code Reviews and Trunk Based Development A reply on Twitter by Michiel Rook regarding When code reviews would not be required Non-Blocking Continuous Code Review - a case study, Thierry de Pauw I Found Something Better Than Pull Requests…, Dave Farley