Tag: book

Book Review: Philosophy of Software Design – Ousterhout

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Overall: 8/10

I can recommend a Philosophy of Software Design Paperback by John Ousterhout. I’ve been programming for 15 years and it closely parallels my own current beliefs about programming. He stands above the lower aspects of programming/code/modules, raising the discussion to a conceptual level, that you seem to be wanting. If I had read this 10 years ago I may have marked it higher but after 15 I’ve already learnt a lot of it through pain. I would keep on ehandy in the office to help me with explaining reasons to junior developers during code reviews.

Book Notes:

Chapter 1/2 – It’s all about complexity.

Formula on page 6 I rougly agree with.
i.e. “complexity is determined by the activities that are most common.” If a system has a few parts that are very complicated but they never need touched, that doesn’t much affect the overall complexity.”
Total Complexity = Sum[ componentComplexity x timeSpentWorkingOnThatPart]

I think his formula for overall complexity is mostly correct: Total Complexity = Sum[ componentComplexity x timeSpentWorkingOnThatPart] However I would replace the timeSpentWorkingOnThatPart with the sum of the square roots of all separate times. i.e. Working on a component for 2 days straight versus working on it 1 hour every 2 weeks are quite different.

Symptoms of Complexity

  • Change amplification – changes require code changes in many places
  • Cognitive Load – How much dev needs to know to complete a task
  • Unknown Unknowns – Not obvious which lines of code must be changed to complete a task
  • In an obvious system a dev can easily see where to make a change in 1-2 places.
  • Complexity is caused by dependencies and obscurity.

Chapter 3 - Strategic vs Tactical

Tactical = Main focus is on getting something working quickly.
Strategic = Working code isn’t enough. Most important is long term system structure.
How much to invest? If all you do is tactical, you build up complexity and code debt which eventually slows you down:

Chapter 4 – Modules should be deep

Abstraction -> Simplified view of an entity, which omits unimportant details.
Deep Modules – The best modules are deep, they provide powerful functionality yet have simple interfaces.
Shallow modules = Classitis = separate functions for everything.

Thoughts…surface area should be connected molecules. With dependencies being thickness of connections? Consider how refactoring would look visually as molecule changes. 

Chapter 5 – Information Hiding

Information leakage – (Opposite of hiding) is when a design decision is reflected in multiple modules creating a dependency.
Temporal Decomposition – When methods must be called in a particular order. Great to finally get a name for this.

Chapter 6 – General Purpose modules are Deeper

Counter-intuitively, “code that is more general purpose is simpler, cleaner and easier to understant.” (Thoughts: this took me years to realise and value!! See Iverson APL )
(Some) Generality leads to better information hiding.
Create general class then push specialization up or down to calling classes.

Chapter 7/8/9

Pass-through methods = Red Flag = No clean separation of responsibility.
Decorators e.g. the old java bufferedInput(FileInput()) is an example of this.
Repetition = Red Flag
Special / General code mix = Red Flag

Pg 61. The amount of complexity exposed to users should be related to number of users to number of developers.

Chapter 10 – Define errors out of existance

His example is unix vs window file deletion. Unix takes care of it in background. Windows refuses and says directory/file is blocked.
Example from my own experience is returning empty lists instead of nulls.

Chapter 11 – Design it twice

Consider multiple approaches, outline them and document pros/cons and which one was chosen and why. (I always do this and make the notes inline or bigger ones in an architecture file. Now that he mentions it I’ve never seen anyone else do this. Crazy they don’t! I guess it does happen in PRs but that’s too late)

Comments – Should describe something that isn’t obvious from the code. it should either be a lower or higher level than the code it’s at.

Pg116 Cross module contents = architecture decisions.  Thoughts: Should I create fake global variable and link cross comments using them. Ensure link stays valid.  

Chapter 14 – Naming
Chapter 15 – Write the comments first
Chapter 16 – Modifying existing code
Chapter 17 – Consistency – Great point!! I’ve learnt how important being consistent in a code base is over many years of pain. Even if the code is not optimal for that area, there’s value in it all being the same pattern everywhere! Only add new if willing to change all other similar parts.
Chapter 20 – Performance = Measure

Crafting Interpreters – Nystrom

I have read this book, went through the exercises and went back to reference this book a number of times.
It’s 10/10 excellent
but I confess I almost forgot to write a review as I mostly read it online and only bought the (heavy book. See pic) to make sure the author got paid for his brilliant work.

Summary: “A comprehensive introduction to writing an interpreter for a dynamically typed, object-oriented toy programming language (Lox). Throughout the book the author develops two complete interpreters for the language from start to finish, including all the front-end and backend parts. The first is a simple AST walking interpreter implemented in Java, and the second is a moderately optimized VM written in C, including a garbage collector.” (src)

Crafting Interpreters Book

Batteries Included = Comes together with all possible parts required for full usability

Every developer should:

  1. Implement a programming language at least once.
  2. Use this book as a guide.

I confess I didn’t arrive at this book naively. I have previously taken 1 university course on compilers and implemented parts of a language naively, i.e. just having a go without any advance thought. If possible I would recommend “having a go” first as it will truly make you appreciate how great this book is.

Robert Nystrom gently leads you down the garden path of creating an interpreter in java and then in C. Even with no C/java experience I think most people could follow along. In fact a major positive of the book is that all code is covered in the book. In theory and mostly in practice I did this. I implemented the language as I followed the book. I wasn’t making his lox language but every step he showed was applicable and useful.

Since I’ve been writing a language on/off for a few years and recently stumbled upon the book. I’ve been particularly interested to read the parts of the book I’ve already implemented to see how someone else approached or thinks about the problem. It has been highly amusing, Robert has some keen insights and his diagrams are brilliant!

If you are a programmer buy this book and more importantly follow it to implement a language that interests you.
The insight it will give you long term is invaluable.

Link to referenced summary: https://eli.thegreenplace.net/2022/book-review-crafting-interpreters-by-robert-nystrom/

Bonus Points: +1 for the author as I emailed them in 2020 when I read the book and they gave a detailed reply to a particularly niche query. Thanks Bob.

Book Review: Traction – Weinberg and Mares

Traction – How any startup can achieve explosive customer growth

Overall: 9/10

I orginally purchased this book in July 2016 and I’ve returned to it throughout the year to re-read sections and twice to re-read it fully. Contains a simple approach that forces developers like me that typically prefer development to sales to
a) Realise the importance of distribution
b) Apply an engineering approach to achieve that.

Book Notes:

Traction = Quantitive evidence of customer demand.

Channels:

  1. Targeting Blogs
  2. Publicity
  3. Unconventional PR
  4. Search Engine Marketing
  5. Social and Display Ads
  6. Offline Ads
  7. Search Engine Optimiziation
  8. Content Marketing
  9. Email Marketing
  10. Engineering as Marketing
  11. Viral Marketing
  12. Business Development – Partnerships
  13. Sales
  14. Affiliaite Programs
  15. Existing Platforms – Facebook, app marketplaces
  16. Trade Shows
  17. Offline Events
  18. Speaking Engagements
  19. Community Building
  • Chapter 2 – Distribution
    • “Almost every failed startup has a product,
      What failed startups don’t have enough of is customers”
    • Traction and Product are equally important, spend 50% on each
    • 1st set a traction goal
      • Make something people want
      • Market it
      • Scale
    • Intially you are NOT trying to capture all the water
      You only need to send enough through to find if it works or where the leaks are.
    • Find bright spots within customer base
  • Chapter 3 BullsEye
    • “It is very likely that one traction channel is optimal”
    • Bullseye – Force to consider all options (find underexploited), then focus on one.
  • How much will it cost to acquire a customer
  • How many customers available through this channel
  • Are they the customers we want now?

Middle Ring – For each construct a cheap test.

“When testing, you are NOT trying to get a lof of customers. You are simply trying to determine if it’s a channel that could move the needle for your startup.”

Chapter 4 – Traction Testing

  • Middle Ring – Goal is to find promising channel
  • Inner Ring
    • Optimization
    • Uncovering strategies within the channel
  • “Over time all marketing strategies result in shitty click through rates” – Andrew Chen

Chapter 5 – Critical Path

  • Traction trumps everything – Define your critical path
  • This may involve stepping stone goals – to develop product or form partnership.
  • This should also dicate product, Do we need SSL/security/SSO for current customers?
  • Lay out your milestones
  • Stay on the critical path.

See also: https://chrisgimmer.com/marketing-flywheel/

2023 May – Additional Notes Update

Sales

  • SPIN – Structuring Sales Conversations – Break ice, clarify, uncover then benefits
  • Situation Questions – How many employees? Company Structure?
  • Problem Question – Are you happy with your current solution?
  • Implication – How does that impact your teams productivity? – Make problem seem larger
  • Need Payoff – How would Pulse help? – Focus on solution and benefits it would bring.

BANTP – Budget, Authority, Need, Timing, Process

Book Review: SRE – Site Reliability Engineering

6/10 – Overall.    8/10 for early chapters, 4/10 for later chapters.
The first 100 pages were excellent but the later chapters were a mixed bag, partially due to rotating authors. I skim-read the later chapters as they mostly focussed on a broad spectrum of not closely related topics.
Chapters that covered topics I interact with were too shallow to interst me, while many chapters were not of interest to me. Perhaps if I was an SRE rather than a developer I would have found the entire book better.

Key Takeways for Me

  1. Every large firm I’ve worked at has been structured incorrectly and had the wrong metrics for measuring stability.
    In banks, the productiodevops-wall-thrown support team has typically been tasked with “zero outages” whilst the developers are incentivised to develop and release as quickly as possible, with some front-office “quant-devs” not being held accountable for stability at all. With the handover method looking like throwing it over a wall:
  2. This book suggests a much better approach:
    Rather than pace vs stability, agree a global “Error Budget” target for everyone. using SLOs/SLIs that if not met can result in moving responstargetibilities back and forth from DEV to SRE owned. Importantly the target e.g. between 99.8% and 99.9% uptime should have an upper and lower bound, it should NOT be an absolute. If you go above it, developers should be taking more risks, below, developers should work on stability.
  3. 100% is the wrong reliability target. I always intuitively knew this but the book provided useful arguments. e.g. If you build 100% reliable but users wifi is 99% reliable, you wasted a lot of effort that users could never benefit from and that took time away from other work.

Book Notes

Note the full book is actually available online here.
An outage is NOT a bad thing, it is an expected part of innovation.

Monitoring

  • Alerts – Immediate human action required
  • Ticket – Human action required within few days to prevent damage
  • Logging – For forentsics/diagnostics only
  • MTTF – Mean Time To Failure
  • MTTR – Mean Time To Repair
  • Humans add latency. MTTR speed critical to availability -> automation is best.

Google Specific Terms

  • Campus > Data centre > cluster > row > rack > server
  • Borg – Automates resources for applications
  • Chubby – Uses paxos to provide global locks
  • Users -> GFrontEnd -> AppFrontEnd -> AppBackEnd -> DB  (all coordinate via Load Balancer / DNS)

Embrace Risk

  • Time Availability = uptime / (uptime+downtime)
  • Aggregate Availability = successful Requests / Total Requests
    This metric is more ususal when there are regional outages etc.
  • There are different types of failure
    • Global outages, regional outages
    • Full outages, partial funcitonality
    • Choose which you want
  • Error Budget = Control loop to manage release velocity
  • Error Budget – Aligns incentives

SLOS

  • SLI – Service Level Indicators – Measure a level of service e.g. latency/availability
  • SLO – Service Level Objective – A range of values that is measured by an SLI e.g. average response <100ms
  • SLA – Agreement – agreed with customers, including consequences for missed SLOs
  • Choosing Targets:
    • Don’t base it on current performance (it could be way off)
    • keep it simple
    • Have as few as possible
    • Keep a safetly margin (tighter internal number)
    • Don’t overachieve, each “9” is costly
  • Percentiles – are better measurement than averages in case of long tail

Toil

  • -> Manual repetitive work devoid of enduring value, that could be automated
  • Toil = Lower morale, career stagnation, slower progress
  • Some amount of toil is unavoidable and can even be calming

Automation

Automation allows super-linear scaling of users vs human effort.

Levels of automation:

  1. Fully automated  – DB self identifies problem and preemptively resolves it
  2. Internally maintained – Generic – script shipped with database
  3. Externally maintained – Generic – shared DB recovery script
  4. Externally Maintained – System Specific – A script on someones desktop
  5. No Automation

Simplicity

  • Less code = Less maintenance
  • Simplicity = Stability

The later chapters held less of interest.
“You want a data recovery system NOT a data backup system.”

SRE Engagement Model – Not all services require SRE attention as they don’t need high reliability and availability. Those teams get given advice and documentation.

Book Review: Accelerate -The Science of Lean Software and Devops

Overall 8/10 – Good book that presents good ideas and clear evidence for why.
I was aware of slightly over half the best practices from this book but not all of them have been adopted by large firms. I picked up a few actions I’d take away but really the usefulness in this book may be in presenting it as evidence to try and drive change in others.

accelerate-book

Book Notes:

Measuring Performance:

  • Use capabilities to measure performance not maturity levels as maturity suggests mission complete.
  • (Scrum) Velocity is only a capacity planning tool
  • Utilization isn’t the correct measure, it should not be 100%
  • Should measure global outcome to ensure teams are not pitted against each other
  • Software Delivery Performance Depends on:
    • Lead time
    • Deployment Frequency
    • Mean Time To Restore
    • Change Fail %

Measuring and Changing Culture

  • Don’t try to change how people think, first change what people do (or change the people :))
  • Westnam Theory: Orgs with better information flow function more effectively
  1. Level 1 – Things we just know
  2. Level 2 – Culture – We can debate these within the team, e.g. importance of security
  3. Level 3 – Written artifacts and established processes

Culture Types:

  1. Pathological – based on power
  2. Bureaucratic – based on rules
  3. Generative – based on performance

Continuous Delivery

Key Principles

  1. Build quality in
  2. Work in small batches
  3. Automate repetition
  4. Relentlessly pursue continuous improvement
  5. Everyone is responsible
  6. Foundations:
    1. Comprehensive config management
    2. Continuous Integration – Small daily branch merges
    3. Continuous Testing

What Works:

  • Version control
  • Test Automation
  • Test data management
  • Trunk based development

Architecture

Goal is loose coupling to ensure bandwidth between teams isn’t swamped with implementation details.
cohesion-coupling
Can the team by itself without speaking to outsiders:
– Change architecture significantly
– Do a deployment? now? during business hours? anytime?

Critical = Tesability and Deployability
Systems are loosely coupled and can be developed and validated independently.

Management Practices

Components of Lean Management

  • Limit work in progress
  • Visual Management
  • Feedback from production
  • Lightweight change approvals

CAB – doesn’t work to increase stability!
External approvals are negatively correlated with lead time, deploy freq. and restore time.
Lean Management <-> Software delivery performance, becomes a virtuous cycle.
Lean: Build -> Measure -> Learn

Capabilities

  • Small batches
  • flow of work from requirements to user known by team
  • Actively seek user feedbck
  • Authority to create/change specs during dev without approval

Sustainable

  • Invest in employee development
  • Foster supportive work environment (no blame)
  • Ask employees what’s preventing them from achieving their objectives
  • Give time to experiment and learn

Factors Causing Employee Burnout:

  • Work overload
  • Lack of control
  • Insufficient rewards
  • Community breakdown
  • Unfairness
  • Value conflicts

Transformational Leadership

  • Vision – Clear understanding of where to be in 5 years
  • Inspiring Communication – Says things that make employee proud to be part of org
  • Intellectually Stimulates – Challenges my assumptions, makes me rethink principles
  • Supportive – Considers and acts to benefit my feelings
  • Personal Recognition – Commends me when I do a good job

 

Key Takeaways for Me:

  1. Most the suggestions from other books I’ve read and that I had seen work myself were correct. The large survey conducted by these authors gives me the evidence to back up my opinions.
  2. Action: In my current work, we need to find a way to get the 3 critical measurements improved. Increased release frequency and lower overhead change management would seem to be the highest effort/reward.
  3. The importance of loosely-coupled architecture gives me a clearer way to conceptualise interactions between teams and why it’s important. (limited bandwidth)

 

US Political Books

On Holiday I took an unusual diversion to read three US political books:

Reagan – Was very biased in favour of Reagan and what a great job he had done.

James Comey – Felt like James honest version of the truth as he saw it, very anti-trump. Some of the situations presented and how everyone tries to manage events to get what they want are interesting.

McCain – Was probably the most balanced book with a few more interesting stories. The best of the bunch.

Book Review: The Five Dysfunctions of a Team

Overall 5/10 – An OK book with little surprising content and an OK story.

five-dysfunctions-of-a-team

I think the core content is true, but the narrative that the author tried to use to deliver his points was thin and didn’t resonate with me.

The one thing this book reminded me of was the interesting research google performed analysing their teams. Over “two years we conducted 200+ interviews with Googlers (our employees) and looked at more than 250 attributes of 180+ active Google teams”, interestingly if you look at their five points (listed 1-5) it closely parallels this book (image below).

  1. Psychological safety: Can we take risks on this team without feeling insecure or embarrassed?
  2. Dependability: Can we count on each other to do high quality work on time?
  3. Structure & clarity: Are goals, roles, and execution plans on our team clear?
  4. Meaning of work: Are we working on something that is personally important for each of us?
  5. Impact of work: Do we fundamentally believe that the work we’re doing matters?

Key Takeaways

five-dysfunctions-of-a-team-levels.png

Each level relies on the one below. A team must first have trust, then no fear of conflict, then commitment to team goals, hold themselves accountable and be commited to team results.

Book Review: The Checklist – Atul Gawande

Overall 6/10 – Good but the few good ideas didn’t justify the book size, some parts felt like filler.

the-checklist-atul-gawande-book-medium.jpg

I liked the idea of this book as a number of processes that I am responsible for involve a long complicated process with many steps of varying difficulty that a developer is likely to forget and I thought the ideas from this book may help. Unfortunately the takeaways do not seem to carry over from medicine to software development.

Book Review: Software Skills – The Software Developers Life Manual

Overall 6/10 – Maybe a more junior/beginning developer would find this useful but for an inexperienced dev it’s mostly common sense.

I bought this book for the wrong reason. I saw it, looked at the index and thought that the content was exactly what I would have wanted as a beginning software developer. Problem being I’m no longer a beginning software developer so too much of the content is no longer useful.

Some Takeaways I did like:

  • Think of yourself, as a business
    • Consider what company long-term suits our goals
    • Market yourself
  • Climbing the Corporate Ladder (Big Company)
    • Take Responsibility – If you take responsibility for something, credit will follow.
    • Become Visible
  • Quota System – Forcing yourself to regularly contribute small pieces towards a big goal

Quirky ideas I wouldn’t have considered but can’t discredit or find interesting include:

  • Hire a professional resume writer. HIs argument is that you only write one and that you are not an expert. I think that could be a sound argument. I once worked for a consulting firm, where they “creatively wrote” the CVs for staff. They could remove parts that were factually true and replace it with what seemed like buzz-word bingo to a techy like me but it worked!
  • Hard work is hard and boring. Sometimes there’s no silver bullet and you just need to put in the work. Sounds obvious but I agree with the author, often people delay or try to find a magical soltuion when what is really needed is hard work. Reminds me of: “..those silver bullets that you and Mike are looking for are fine and good, but our web server is five times slower. There is no silver bullet that’s going to fix that. No, we are going to have to use a lot of lead bullets.” – Bill Turnpin
  • Any action is better than no action