CSC309 Lecture 07

Software Engineering II
Technical Debt
(202304)

Transcript

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   CSC 309
   Software Engineering II
   Lecture 07:
   Technical Debt
   Dr. Javier Gonzalez-Sanchez
   javiergs@calpoly.edu
   www.javiergs.com
   Building 14 -227
   Office Hours: By appointment
   

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   § It is the result of prioritizing speedy delivery over perfect code.
   § It is a metaphor to raise awareness:
   A debt requires interest payment (extra development effort).
   § A little debt speeds development so long as it is paid back promptly.
   The danger occurs when the debt is not repaid.
   Every minute spent on not-quite-right code counts as interest on debt
   – R. Cunningham (1992)
   Technical Debt
   

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   What is Speed?
   Velocity = story points/time
   Example:
   Velocity = 80 / 6 = 13.33
   

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   Attempting to Falsely Accelerate Velocity
   Work that we
   Decide not to do.
   Such as testing
   

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   § Unpredictable tipping point. Debt grows in an unpredictable nonlinear fashion.
   § Increased time to delivery. The greater the debt today, the slower the velocity tomorrow.
   § Defects. Debt increase complexity; therefore, it is harder to do things correctly.
   § Rising Cost of Change. Built + Repair
   § Product Atrophy. Product ceases to be a viable option.
   § Decreased predictability. Any prediction is nearly impossible. Estimates become bad
   estimates even for the most experienced team members.
   § Underperformance (teamwork). Increment of technical debt lower development performance
   and therefore reduce expectations of what is possible.
   § Frustration. People burn out.
   Consequences
   

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   Technical Debt
   Bad design
   Defects
   Insufficient test coverage
   Excessive manual testing
   Poor integration
   management
   Definition
   1. Naïve Debt
   2. Unavoidable Debt
   3. Strategic Debt
   bad things that
   plague systems
   

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   § Not originally intended to be referred to as technical debt (Cunningham).
   Unintentional debt (McConnell 2007).
   Just mess (Martin 2008)
   Reckless debt (Fowler 2009).
   § Origin:
   Team members or business immaturity or process deficiencies that lead
   to sloppy design, poor engineering practices, and a lack of testing.
   § Solution:
   Proper training.
   Good understanding of technical practices.
   Naïve Debt
   

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   § Unpredictable and unpreventable.
   § Product and product design evolution over time.
   § Origin:
   Design and implementation decisions.
   § Solution:
   No big deal, just payback, sooner the better
   Unavoidable Debt
   

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   § Debt can be a tool that can be used to better quantify and leverage the
   economics of important time-sensitive decisions.
   § Origin:
   Shortcuts during product development to achieve a short-term goal.
   § Solution:
   It is a tool, but as with any debt, it should be repaid.
   Strategic Debt
   

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10. Manage Technical Debt
    

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    1. Avoid accrual, i.e., the accumulation or increase of debt over time.
    2. Make debt visible, i.e., do not ignore it or try to hide it. Experts could
    assume you are naïve.
    3. Repay periodically, i.e., schedule your payments as a routine. Each sprint
    uses some resources (time) to pay selected (targeted technical debt).
    Activities for managing technical debt
    

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    § No product is debt free.
    So how much technical debt can we take on?
    § As a team,
    balance business and technical perspectives to make trade-offs.
    § But,
    Do Not add naïve debt.
    Do TDD, automating testing, continuous integration, refactoring, etc.
    • Track velocity over time
    Key ideas
    

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    • Boy Scout rule
    Leave the campground cleaner than you found it
    Clean up until you reach a predefined threshold.
    And classify the rest, adding entries into the product backlog, such as a
    [known technical debt]
    Key Ideas
    

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    Questions
    

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    § Textbook Chapter 8.
    Reference
    

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    Office Hours
    Tuesday and Thursday 3 - 5 pm
    But an appointment required
    Sent me an email – javiergs@calpoly.edu
    

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    CSC 309
    Software Engineering II
    Lab 07:
    Technical Debt
    Dr. Javier Gonzalez-Sanchez
    javiergs@calpoly.edu
    Building 14 -227
    Office Hours: By appointment
    

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    Let’s Work
    Do you have Technical Debt?
    Which one (Naïve, Unavoidable, Strategic)?
    What is the plan for
    managing technical debt
    (including but not limited to REPAY)?
    What is your current velocity (Sprint zero)?
    

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    CSC 309 Software Engineering II
    Javier Gonzalez-Sanchez, Ph.D.
    javiergs@calpoly.edu
    Winter 2023
    Copyright. These slides can only be used as study material for the class CSC308 at Cal Poly.
    They cannot be distributed or used for another purpose.
    

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