The Technical Debt Trap - NDC Oslo 2014

  • 1,370 views
Uploaded on

Technical Debt has become a catch-all phrase for any code that needs to be re-worked. Much like Refactoring has become a catch-all phrase for any activity that involves changing code. These …

Technical Debt has become a catch-all phrase for any code that needs to be re-worked. Much like Refactoring has become a catch-all phrase for any activity that involves changing code. These fundamental misunderstandings and comfortable yet mis-applied metaphors have resulted in a plethora of poor decisions. What is technical debt? What is not technical debt? Why should we care? What is the cost of misunderstanding? What do we do about it? Doc discusses the origins of the metaphor, what it means today, and how we properly identify and manage technical debt.

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
No Downloads

Views

Total Views
1,370
On Slideshare
0
From Embeds
0
Number of Embeds
1

Actions

Shares
Downloads
21
Comments
2
Likes
9

Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide

Transcript

  • 1. The
 Technical Debt Trap Doc Norton doc@groupon.com @DocOnDev
  • 2. Doc Norton! Global Director of Engineering Culture! doc@groupon.com | @DocOnDev Husband Father
  • 3. Grandfather!
  • 4. What is Technical Debt?
  • 5. Shipping first time code is like going into debt. OOPSLA ‘92 Ward Cunningham
  • 6. Shipping first time code is like going into debt. A little debt speeds development so long as it is paid back promptly with a rewrite. OOPSLA ‘92 Ward Cunningham
  • 7. The danger occurs when the debt is not repaid. Every minute spent on not-quite-right code counts as interest on that debt. OOPSLA ‘92 Ward Cunningham
  • 8. The danger occurs when the debt is not repaid. Every minute spent on not-quite-right code counts as interest on that debt. OOPSLA ‘92 Ward Cunningham
  • 9. Technical Debt is Good
  • 10. WTF? Technical Debt is Good
  • 11. Technical Debt is Good Strategic Design Decision ❖ Allow for Rapid Delivery! ❖ To Elicit Quick Feedback! ❖ And Correct Design
  • 12. Technical Debt is Good Indication of Learning ❖ Now know what you need! ❖ Implementation doesn’t match!
  • 13. Technical Debt is a Metaphor Here Be Danger
  • 14. Metaphor’s Rock We Reason by Analogy Building on a weak foundation Puts pressure on our design Can’t keep running at this pace It’s raining men (hallelujah)
  • 15. Metaphorphosis When Metaphors Go Wrong SHORT-TERM Long-Term INADVERTENT RECKLESS DEBT IN THE THIRD QUADRANTPrudent Intentional Credit Card FRAUDULENT AUTO LOAN Student Loan HOME LOAN Loan Shark Return on Investment PYRAMID SCHEME VOLUNTARY PRAGMATIC LEVERAGE HIGH INTEREST OPERATIONAL
  • 16. Metaphorphosis When Metaphors Go Wrong “QUICK AND DIRTY” MARTIN FOWLER HTTP://WWW.MARTINFOWLER.COM/BLIKI/TECHNICALDEBT.HTML “SLOPPY” DAVID LARIBEE HTTP://MSDN.MICROSOFT.COM/EN-US/MAGAZINE/EE819135.ASPX “JUST HACK IT IN” STEVE MCCONNELL HTTP://BLOGS.CONSTRUX.COM/BLOGS/STEVEMCC/ARCHIVE/2007/11/01/TECHNICAL-DEBT-2.ASPX “CUT A LOT OF CORNERS” JAMES SHORE HTTP://JAMESSHORE.COM/BLOG/CARDMEETING/VOLUNTARY-TECHNICAL-DEBT.HTML
  • 17. The Technical Debt Quadrant http://martinfowler.com/bliki/TechnicalDebtQuadrant.html
  • 18. [Many] have explained the debt metaphor and confused it with the idea that you could write code poorly with the intention of doing a good job later. YouTube ‘09 Ummm… No. http://www.youtube.com/watch?v=pqeJFYwnkjE&feature=player_embedded
  • 19. confused the debt metaphor with the idea that you could write code poorly
  • 20. The ability to pay back debt [...] depends upon you writing code that is clean enough to be able to refactor as you come to understand your problem. YouTube ‘09 Clean Code is Required http://www.youtube.com/watch?v=pqeJFYwnkjE&feature=player_embedded
  • 21. The ability to pay back debt [...] depends upon you writing code that is clean enough to be able to refactor as you come to understand your problem. YouTube ‘09 Clean Code is Required http://www.youtube.com/watch?v=pqeJFYwnkjE&feature=player_embedded
  • 22. Twitter ‘09 Dirty Code is a Bad Idea Dirty code is to technical debt as the pawn broker is to financial debt.! http://twitter.com/WardCunningham/status/3742903303 Don’t think you are ever going to get your code back.
  • 23. Is it Technical Debt? Ask yourself… ❖ Is the code clean?! ❖ Is the code tested?! ❖ Is there a learning objective or event?! ❖ Is there a plan for payback?! ❖ Is the business truly informed?
  • 24. Is it Technical Debt? If you say no to even one… ❖ Is the code clean?! ❖ Is the code tested?! ❖ Is there a learning objective or event?! ❖ Is there a plan for payback?! ❖ Is the business truly informed? ... then you don’t have Technical Debt
  • 25. You have a mess Mess (noun) ❖ Disorderly accumulation, heap, or jumble! ❖ A state of embarrassing confusion! ❖ An unpleasant or difficult situation
  • 26. You have cruft Cruft (noun) ❖ An unpleasant substance! ❖ The result of shoddy construction! ❖ Redundant, old or improperly written code
  • 27. Chill. It’s just semantics, man. Just Semantics? Technical Debt is Good
  • 28. Chill. It’s just semantics, man. Just Semantics? Technical Debt is GoodQuick and Dirty is Technical DebtQuick and Dirty is Good
  • 29. Chill. It’s just semantics, man. Just Semantics? Quick and Dirty is GoodQuick and Dirty is Good
  • 30. The Technical Debt Quadrant http://martinfowler.com/bliki/TechnicalDebtQuadrant.html
  • 31. The Technical Debt Quadrant http://martinfowler.com/bliki/TechnicalDebtQuadrant.html “Let’s deploy and gather more information.”
  • 32. Technical Debt in Other Fields
  • 33. Technical Debt in Other Fields
  • 34. Technical Debt in Other Fields
  • 35. Technical Debt in Other Fields RECKLESS AND DELIBERATE RECKLESS AND DELIBERATE RECKLESS AND INADVERTENT
  • 36. The Technical Debt Quadrant http://martinfowler.com/bliki/TechnicalDebtQuadrant.html IRRESPONSIBLE INCOMPETENT “Let’s deploy and gather more information.” TECHNICAL DEBT
  • 37. Cruft or Debt? DataSet aDs, qDs;! aDs = _dbConnector.UpdateAgentList();! qDs = _dbConnector.GetQueueList();! foreach (DataTable aTable in aDs.Tables) {! foreach (DataRow aRow in aTable.Rows) {! foreach (DataColumn aColumn in aTable.Columns) {! DataSet asDs = _dbConnector.GetAgentSkills(aRow[aColumn].ToString());//AgentId! foreach (DataTable asTable in asDs.Tables) {! foreach (DataRow asRow in asTable.Rows) {! foreach (DataColumn asColumn in asTable.Columns) {! foreach (DataTable qTable in qDs.Tables) {! foreach (DataRow qRow in qTable.Rows) {! foreach (DataColumn qColumn in qTable.Columns) {! DataSet sqDs = _dbConnector.GetSkillsForQueue(qRow[qColumn].ToString());! foreach (DataTable sqTable in sqDs.Tables) {! foreach (DataRow sqRow in sqTable.Rows) {! foreach (DataColumn sqColumn in sqTable.Columns) {! foreach (string skill in sqRow[sqColumn].ToString().Split(paramDelimStr)) {! if (skill == asRow[asColumn].ToString()) {! try {! _dbConnector.SetAgentQueueSkill(aRow[aColumn].ToString(),! qRow[qColumn].ToString(),! skill);! }! catch { continue; }! }! }! }! }! }! }! }! }! }! }! }! }! }! } http://thedailywtf.com/Series/2010/3/CodeSOD.aspx
  • 38. Cruft or Debt? DataSet aDs, qDs;! aDs = _dbConnector.UpdateAgentList();! qDs = _dbConnector.GetQueueList();! foreach (DataTable aTable in aDs.Tables) {! foreach (DataRow aRow in aTable.Rows) {! foreach (DataColumn aColumn in aTable.Columns) {! DataSet asDs = _dbConnector.GetAgentSkills(aRow[aColumn].ToString());//AgentId! foreach (DataTable asTable in asDs.Tables) {! foreach (DataRow asRow in asTable.Rows) {! foreach (DataColumn asColumn in asTable.Columns) {! foreach (DataTable qTable in qDs.Tables) {! foreach (DataRow qRow in qTable.Rows) {! foreach (DataColumn qColumn in qTable.Columns) {! DataSet sqDs = _dbConnector.GetSkillsForQueue(qRow[qColumn].ToString());! foreach (DataTable sqTable in sqDs.Tables) {! foreach (DataRow sqRow in sqTable.Rows) {! foreach (DataColumn sqColumn in sqTable.Columns) {! foreach (string skill in sqRow[sqColumn].ToString().Split(paramDelimStr)) {! if (skill == asRow[asColumn].ToString()) {! try {! _dbConnector.SetAgentQueueSkill(aRow[aColumn].ToString(),! qRow[qColumn].ToString(),! skill);! }! catch { continue; }! }! } } } } } } } } } } } } } http://thedailywtf.com/Series/2010/3/CodeSOD.aspx
  • 39. Cruft or Debt? DataSet aDs, qDs, asDs, sqDs;! aDs = _dbConnector.UpdateAgentList();! qDs = _dbConnector.GetQueueList();! ! foreach (DataRow aRow in aDS.Tables[0].Rows) {! String agentID = aRow[“AgentId”].ToString();! asDs = _dbConnector.GetAgentSkills(agentID);! foreach (DataRow asRow in asDs.Tables[0].Rows) {! String agentSkill = asRow[“Skill”].ToString();! foreach (DataRow qRow in qDs.Tables[0].Rows) {! queueName = qRow[“QueueName”].ToString();! sqDs = _dbConnector.GetSkillsForQueue(queueName);! foreach (DataRow sqRow in sqDs.Tables[0].Rows) {! foreach (string skill in sqRow[“Skills”].ToString().Split(paramDelimStr)) {! if (skill == agentSkill) {! try { _dbConnector.SetAgentQueueSkill(agentID, queueName, skill); }! catch { continue; }! }! }! }! }! }! } http://thedailywtf.com/Series/2010/3/CodeSOD.aspx
  • 40. Cruft or Debt? AgentList agents = new AgentList(_dbConnector.UpdateAgentList());! QueueList queues = new QueueList(_dbConnector.GetQueueList());! ! foreach (Agent agent in agents) {! foreach (Skill agentSkill in agent.skills) {! foreach (Queue queue in queues) {! foreach (Skill queueSkill in queue.skills.Where(x => x == agentSkill)) {! try {_dbConnector.SetAgentQueueSkill(agent.agentID, queue.name, agentSkill); }! catch { continue; }! }! }! }! } http://thedailywtf.com/Series/2010/3/CodeSOD.aspx
  • 41. Cruft or Debt? if ((customer.state == “AL” && customer.type ==! CustomerType.GENERAL_AGENT && customer.revenue > 100000)! || (customer.type == CustomerType.RETRO_AGENT &&! (customer.state == “WI” || customer.state == “IL”))! || (customer.type == CustomerType.FED_MANAGEMENT &&! customer.revenue > 150000)) { ... }
  • 42. Cruft or Debt? // If customer is Federally Regulated! if ((customer.state == “AL” && customer.type ==! CustomerType.GENERAL_AGENT && customer.revenue > 100000)! || (customer.type == CustomerType.RETRO_AGENT &&! (customer.state == “WI” || customer.state == “IL”))! || (customer.type == CustomerType.FED_MANAGEMENT &&! customer.revenue > 150000)) { ... }
  • 43. Cruft or Debt? if (customer.isFederallyRegulated()) { ... }
  • 44. Cruft or Debt? double getSpeed() {! switch (_type) {! case EUROPEAN:! return getBaseSpeed();! case AFRICAN:! return getBaseSpeed() - getLoadFactor() * _numberOfCoconuts;! case NORWEGIAN_BLUE:! return (_isNailed) ? 0 : getBaseSpeed(_voltage);! }! throw new RuntimeException ("Should be unreachable");! }! http://www.refactoring.com/catalog/replaceConditionalWithPolymorphism.html
  • 45. Cruft or Debt? class Swallow ...! double getSpeed() { return getBaseSpeed(); }! end class! ! class EuropeanSwallow ...! end class! ! class AfricanSwallow ...! double getSpeed() { return super.getSpeed - coconutLoad(); }! double coconutLoad() { return getLoadFactor() * _numberOfCoconuts; }! end class! ! class NorwegianSwallow ...! double getSpeed() { return (_isNailed) ? 0 : getBaseSpeed(_voltage); }! end class
  • 46. Cruft is a bad decision Every Time ❖ You are a professional developer! ❖ You’re going to create unintentional cruft! ❖ You have to clean up the existing cruft
  • 47. The Trap Cruft begets Cruft ❖ Precedent for speed over quality! ❖ Expectation of increased velocity! ❖ Cruft slows you down! ❖ Must write more cruft to keep up! ❖ Ask permission to do your job correctly
  • 48. Avoid The Trap Thresholds set false expectations http://blog.castsoftware.com/wp-content/uploads/2011/04/Technical-Debt-Software-Quality1.jpg
  • 49. Avoid The Trap Incremental fixes fail http://www.jacoozi.com/blog/wp-content/uploads/2007/01/refactoring_coc_big.jpg
  • 50. http://www.jacoozi.com/blog/wp-content/uploads/2007/01/refactoring_coc_big.jpg
  • 51. Avoid The Trap Clean Constantly ❖ Never make an intentional mess! ❖ Monitor your “Technical Debt”! ❖ Follow the Boy Scout Rule! ❖ Remember quality is your responsibility! ❖ NEVER ask permission to do your job correctly
  • 52. Monitoring Cruft/Debt A few key metrics ❖ Code Coverage! ❖ Code Complexity! ❖ Coupling! ❖ Maintainability
  • 53. Monitoring Cruft/Debt Code Coverage ❖ Code exercised by automated tests! ❖ Monitor types of tests separately! ❖ Don’t set a coverage target! ❖ 100% coverage is a smell! ❖ Monitor Trends, Not Points
  • 54. Monitoring Cruft/Debt Complexity ❖ Count of logical branches in code! ❖ Direct relationship with bugs! ❖ Typically high in concentrated areas! ❖ Reduce conditionals! ❖ Monitor Trends, Not Points
  • 55. Monitoring Cruft/Debt Coupling ❖ Interconnectedness of systems! ❖ Highly coupled is difficult to change! ❖ Afferent (toward) and Efferent (away)! ❖ Dependency Injection! ❖ Monitor Trends, Not Points
  • 56. Monitoring Cruft/Debt Make stories for cruft ❖ Velocity! ❖ Scalability! ❖ Availability! ❖ Maintainability
  • 57. Review Technical Debt ❖ A strategic design decision! ❖ Requires business to be informed! ❖ Includes a pay-back plan Cruft ❖ Happens! ❖ Needs to be monitored and cleaned! ❖ Is NOT Technical Debt
  • 58. Review Technical Debt ❖ A strategic design decision! ❖ Requires business to be informed! ❖ Includes a pay-back plan Cruft ❖ Happens! ❖ Needs to be monitored and cleaned! ❖ Is NOT Technical Debt NEVER ask perm ission to do your job correctly
  • 59. The
 Technical Debt Trap Doc Norton! doc@groupon.com! @DocOnDev Comments / Questions?
  • 60. The
 Technical Debt Trap Doc Norton! doc@groupon.com! @DocOnDev Thank You!