際際滷

際際滷Share a Scribd company logo

Technical Debt

K
Kmanthei

The document discusses the concept of technical debt, which is code quality issues or design issues that are intentionally deferred for a future date in order to quickly deliver new features. This debt needs to be paid back at a later time which becomes more difficult and costly the longer it is deferred. The key points made are: - Technical debt is a metaphor for code quality issues that accrue over time if not addressed. - Symptoms of high technical debt include slower development velocity, difficulty implementing new features, and low code quality. - Strategies for managing technical debt include refactoring a little at a time with each change, using the "stangler" pattern of gradually replacing parts of an application, and occasionally stopping

1 of 47
Downloaded 37 times
Technical Debt The Silent Application Killer 息 ThoughtWorks 2011 Tuesday, 8 November 11
Graham Brooks http://www.thoughtworks.com/blogs/current http://www.grahambrooks.com/blog @wookie870 息 ThoughtWorks 2011 Tuesday, 8 November 11
Outline De鍖nition Why is it important? Symptoms and signs Debt resolution strategies Tuesday, 8 November 11
Technical Debt Tuesday, 8 November 11
Technical Debt Metaphor coined by Ward Cunningham to explain the misalignment between code and current understanding Tuesday, 8 November 11
Consciously taking on debt might allow you to get something sooner Tuesday, 8 November 11
Burden Not paying off - borrowing without paying it back Spending power goes to 0 All your money goes into paying interest Tuesday, 8 November 11
Some might see this as an excuse to write poor code. Never write poor code Tuesday, 8 November 11
Reckless Prudent We must ship now We dont Deliberate and deal with the have time consequences for design Now we know Inadvertent What is layering? how we should have built it source: http://martinfowler.com/bliki/TechnicalDebtQuadrant.html Tuesday, 8 November 11
Evidence is anecdotal and based on personal experience of many projects Tuesday, 8 November 11
No debt Management Cost of Change Time Tuesday, 8 November 11
A re-write will... Solve all our problems If we use language X The latest framework A new code generator A new database ..... Tuesday, 8 November 11
Cost of change Time Tuesday, 8 November 11
Teams like these get better at rewrites. They dont learn how to continuously deliver value inde鍖nitely..... Tuesday, 8 November 11
No debt Management Cost of Change Technical Debt Managed Time Tuesday, 8 November 11
Your codebase can never be in Credit For commercial projects technical debt is a fact of life You either have enough or too much Tuesday, 8 November 11
Symptoms and Signs Tuesday, 8 November 11
Productivity Tuesday, 8 November 11
Velocity Iteration Tuesday, 8 November 11
Velocity Iteration Tuesday, 8 November 11
Velocity Iteration Tuesday, 8 November 11
Velocity Iteration Tuesday, 8 November 11
Velocity Iteration Tuesday, 8 November 11
Velocity Iteration Tuesday, 8 November 11
Tracer Stories 11Point Point 11Point Point 11Point Point 11Point Point Velocity 7h 5h 7h 10h Time 5-10 months Iteration Tuesday, 8 November 11
Code Tuesday, 8 November 11
Code Review Tuesday, 8 November 11
You know you are working on clean code when each routine you read turns out to be pretty much what you expected.You can call it beautiful code when the code also makes it look like the language was made for the problem Ward Cunningham Clean Code by Robert C Martin Tuesday, 8 November 11
http://www.osnews.com/story/19266/WTFs_m Tuesday, 8 November 11
Readability is a key Tuesday, 8 November 11
How often features are used Never Rarely Sometimes 45% Often NEVER USED Always 0 12.5 25 37.5 50 Source: Standish Group Tuesday, 8 November 11
Remove Unused stuff Unused features Unused 鍖les and tools Unused classes Unused methods Unused lines Tuesday, 8 November 11
Duplication Direct duplication Exact Code copies Aggressive Algorithmically Equivolent Tool tip: Simian Tuesday, 8 November 11
!" #!" $!" %!" &!" '!!" '#!" '$!" '%!" 0569?-**" 50-:?-**" (>4,+@?2A" 59.-5?-**" (;50-:?A" 01D8?F=+" Tuesday, 8 November 11 340569?A" 0159.-5?A" +.509?-**" :6D+6?.=" H.5.?-**" ==01?A" 01H.5.?A" ?-*90I6-5" >4,+@?F=+" (?*90I6-5" .869?-**" (25@.LF?A" ?-*90I6-5" :6D+6?.=" K625?-**" 5K625?-**" 509<?-**" .869?-**" 1C+.22?A" 0++69?-**" C+.22?-**" 0<NO?F=+" .1.869?A" 22,01?-**" 1590+?-**" !"##$%&!"'(%& -4+.509?A" 01D8?F=+" (?*90I6-5" 15?-2*90I" Volatility +,615?-**" <Q4<?-**" +,615?-**" 5K625?-**" +,615?-**" +,615?-**" @,.509?-2" +,615?-**" 590++69?A" 1,509?-**" K625?-**" @+69?-**" ,/.+,U69?A" 9K625?-**" 09=?962F" C0==,5"C0415"
Toxicity 250 branches in a single class Tuesday, 8 November 11
Clean Toxic Volatile Volatile requirements? !Refactor Now! Monitor Stable Leave alone Refactor later Tuesday, 8 November 11
ures /feat te sts r of O C m be on L u ti N pl ica Ap C LO Te st Time Tuesday, 8 November 11
Debt resolution strategies Tuesday, 8 November 11
Stop the Line Works for major changes Challenging to implement Smells of a rewrite Short Tuesday, 8 November 11
Little and often Make improvement part of the process: Improvement as part of every change Stangler pattern Tuesday, 8 November 11
Its going to get worse before it gets better Desired State Productivity Current Situation Cost of Change Time Tuesday, 8 November 11
Closing Thoughts Tuesday, 8 November 11
First Steps Imagine you have joined a new team Run metrics Estimate debt Plan next steps Execute the plan Tuesday, 8 November 11
Software Rusts Things Change New capabilities Libraries Frameworks OS Tuesday, 8 November 11
Every modi鍖cation of a system might incur technical debt unless it is accompanied by some effort to bring the design into line with the requirements. Tuesday, 8 November 11
Questions? Tuesday, 8 November 11
Thank You! http://www.thoughtworks.com/blogs/current http://www.grahambrooks.com/blog @wookie870 gbrooks@thoughtworks.com 息 ThoughtWorks 2008 Tuesday, 8 November 11

More Related Content

Technical Debt

  • 1. Technical Debt The Silent Application Killer 息 ThoughtWorks 2011 Tuesday, 8 November 11
  • 2. Graham Brooks http://www.thoughtworks.com/blogs/current http://www.grahambrooks.com/blog @wookie870 息 ThoughtWorks 2011 Tuesday, 8 November 11
  • 3. Outline De鍖nition Why is it important? Symptoms and signs Debt resolution strategies Tuesday, 8 November 11
  • 5. Technical Debt Metaphor coined by Ward Cunningham to explain the misalignment between code and current understanding Tuesday, 8 November 11
  • 6. Consciously taking on debt might allow you to get something sooner Tuesday, 8 November 11
  • 7. Burden Not paying off - borrowing without paying it back Spending power goes to 0 All your money goes into paying interest Tuesday, 8 November 11
  • 8. Some might see this as an excuse to write poor code. Never write poor code Tuesday, 8 November 11
  • 9. Reckless Prudent We must ship now We dont Deliberate and deal with the have time consequences for design Now we know Inadvertent What is layering? how we should have built it source: http://martinfowler.com/bliki/TechnicalDebtQuadrant.html Tuesday, 8 November 11
  • 10. Evidence is anecdotal and based on personal experience of many projects Tuesday, 8 November 11
  • 11. No debt Management Cost of Change Time Tuesday, 8 November 11
  • 12. A re-write will... Solve all our problems If we use language X The latest framework A new code generator A new database ..... Tuesday, 8 November 11
  • 13. Cost of change Time Tuesday, 8 November 11
  • 14. Teams like these get better at rewrites. They dont learn how to continuously deliver value inde鍖nitely..... Tuesday, 8 November 11
  • 15. No debt Management Cost of Change Technical Debt Managed Time Tuesday, 8 November 11
  • 16. Your codebase can never be in Credit For commercial projects technical debt is a fact of life You either have enough or too much Tuesday, 8 November 11
  • 19. Velocity Iteration Tuesday, 8 November 11
  • 20. Velocity Iteration Tuesday, 8 November 11
  • 21. Velocity Iteration Tuesday, 8 November 11
  • 22. Velocity Iteration Tuesday, 8 November 11
  • 23. Velocity Iteration Tuesday, 8 November 11
  • 24. Velocity Iteration Tuesday, 8 November 11
  • 25. Tracer Stories 11Point Point 11Point Point 11Point Point 11Point Point Velocity 7h 5h 7h 10h Time 5-10 months Iteration Tuesday, 8 November 11
  • 27. Code Review Tuesday, 8 November 11
  • 28. You know you are working on clean code when each routine you read turns out to be pretty much what you expected.You can call it beautiful code when the code also makes it look like the language was made for the problem Ward Cunningham Clean Code by Robert C Martin Tuesday, 8 November 11
  • 30. Readability is a key Tuesday, 8 November 11
  • 31. How often features are used Never Rarely Sometimes 45% Often NEVER USED Always 0 12.5 25 37.5 50 Source: Standish Group Tuesday, 8 November 11
  • 32. Remove Unused stuff Unused features Unused 鍖les and tools Unused classes Unused methods Unused lines Tuesday, 8 November 11
  • 33. Duplication Direct duplication Exact Code copies Aggressive Algorithmically Equivolent Tool tip: Simian Tuesday, 8 November 11
  • 34. !" #!" $!" %!" &!" '!!" '#!" '$!" '%!" 0569?-**" 50-:?-**" (>4,+@?2A" 59.-5?-**" (;50-:?A" 01D8?F=+" Tuesday, 8 November 11 340569?A" 0159.-5?A" +.509?-**" :6D+6?.=" H.5.?-**" ==01?A" 01H.5.?A" ?-*90I6-5" >4,+@?F=+" (?*90I6-5" .869?-**" (25@.LF?A" ?-*90I6-5" :6D+6?.=" K625?-**" 5K625?-**" 509<?-**" .869?-**" 1C+.22?A" 0++69?-**" C+.22?-**" 0<NO?F=+" .1.869?A" 22,01?-**" 1590+?-**" !"##$%&!"'(%& -4+.509?A" 01D8?F=+" (?*90I6-5" 15?-2*90I" Volatility +,615?-**" <Q4<?-**" +,615?-**" 5K625?-**" +,615?-**" +,615?-**" @,.509?-2" +,615?-**" 590++69?A" 1,509?-**" K625?-**" @+69?-**" ,/.+,U69?A" 9K625?-**" 09=?962F" C0==,5"C0415"
  • 35. Toxicity 250 branches in a single class Tuesday, 8 November 11
  • 36. Clean Toxic Volatile Volatile requirements? !Refactor Now! Monitor Stable Leave alone Refactor later Tuesday, 8 November 11
  • 37. ures /feat te sts r of O C m be on L u ti N pl ica Ap C LO Te st Time Tuesday, 8 November 11
  • 38. Debt resolution strategies Tuesday, 8 November 11
  • 39. Stop the Line Works for major changes Challenging to implement Smells of a rewrite Short Tuesday, 8 November 11
  • 40. Little and often Make improvement part of the process: Improvement as part of every change Stangler pattern Tuesday, 8 November 11
  • 41. Its going to get worse before it gets better Desired State Productivity Current Situation Cost of Change Time Tuesday, 8 November 11
  • 43. First Steps Imagine you have joined a new team Run metrics Estimate debt Plan next steps Execute the plan Tuesday, 8 November 11
  • 44. Software Rusts Things Change New capabilities Libraries Frameworks OS Tuesday, 8 November 11
  • 45. Every modi鍖cation of a system might incur technical debt unless it is accompanied by some effort to bring the design into line with the requirements. Tuesday, 8 November 11
  • 47. Thank You! http://www.thoughtworks.com/blogs/current http://www.grahambrooks.com/blog @wookie870 gbrooks@thoughtworks.com 息 ThoughtWorks 2008 Tuesday, 8 November 11