Embrace The Past How Software Evolution Lets You Understand Large - PowerPoint PPT Presentation

Embrace The Past How Software Evolution Lets You Understand Large Codebases @AdamTornhill adam.tornhill@empear.com http://www.empear.com/

Motivation

Is it a Failure to Improve? Most complex component @AdamTornhill

Technical Debt - How Much Is Enough?

Is a Man-Month Still Mythical? Responsible for the merge https://pragprog.com/book/atcrime/your-code-as-a-crime-scene

Why Do We Keep Repeating The Same Misstakes? What’s absent? Time and Social Information! @AdamTornhill

Embrace The Past Time Social information @AdamTornhill

All Code is Equal …but some Code is more equal than others* * Sorry, George Orwell

Change Distribution of Files 12 Years of Ruby on Rails 1 Year in Roslyn (C#, VB) 6 Years of Erlang Change Frequency Each file in the system

Hotspots - A Tool To Prioritize @AdamTornhill

Hotspot Code Complexity Code Change Frequency @AdamTornhill

Hotspots - A Tool To Prioritize Hotspots Hotspots

Code is Auto-Destructive Art

Focus on the Code that Matters 2.6% of the code, 15.5% effort 2.5% of the code, 11.0% effort 2.4% of the code, 13.3% effort ASP.NET MVC 200 kLoC Mono 6.7 MLoC Docker 500 kLoC @AdamTornhill

Prioritize with Hotspots Complex Code Important Hotspots: ~3-6% of the total Code @AdamTornhill

Normalization of Deviance @AdamTornhill

Supervise your Complexity Trends Refactoring Complexity Increasing complexity Increases again Lines of Code @AdamTornhill

Software Half-Life “ Reducing this half-life means any code you are looking at is likely to be either very recent or old. We discover that reasoning about code becomes harder when there is lots of code in the grey area between these two. ” Dan North https://leanpub.com/software-faster

Evolutionary Stable Code Young Code Old Code @AdamTornhill

Case Study: Commodities in Clojure @AdamTornhill

Case Study: Commodities in Clojure Package: “asm” - ClassReader.java - MethodWriter.java - … @AdamTornhill

Case Study: Commodities in Clojure @AdamTornhill

Case Study: CPython cjkcodecs - … Different Rates of Change multibytecodec.c => 1 month since last change mappings => 10 years (!) since last change @AdamTornhill

Code Age : a much underused driver of software design . What if… …we organize our code by age? …we turn stable packages into libraries? …we move and refactor code that fails to stabilize? @AdamTornhill

Organizational problems are mistaken as technical issues @AdamTornhill

A Social View of Clojure

A Social View of Clojure Rich Hickey Stuart Halloway … … …

Teams Underperform

Process Loss Individual Contributions Team Work Real Productivity The Potential Productivity Process Loss @AdamTornhill

Study Team Coordination

Measuring Conway’s Law Features Architectural Pattern: Package by Feature Views @AdamTornhill

Team The Perils of Feature Teams Team Team Team Team Team Team Team Team Team Team Team @AdamTornhill

The Gatekeeper/Architect Pattern https://en.wikipedia.org/wiki/Amdahl%27s_law @AdamTornhill

Alternative: The Team as Gatekeeper @AdamTornhill

Diffusion of Responsibility

Why Hotspots stay where they are Immutable Design

Align Your Architecture and your Organisation @AdamTornhill

Make Decisions Influenced By Data @AdamTornhill

Read More www.adamtornhill.com/articles/aspnetclones/killtheclones.html www.adamtornhill.com/articles/socialside/socialsideofcode.htm The Tools as a Service (work in progress) https://codescene.io/ @AdamTornhill adam.tornhill@empear.com http://www.empear.com/