Dr Administrator

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Book review: A Philosophy of Software Design by John Ousterhout

Next for review is A Philosophy of Software Design by John Ousterhout. This a book about a big idea for software design. The big idea is that good software design is about managing complexity. In Ousterhout’s view complexity leads to a set of bad things: (1) change amplification – small changes in code lead to big effects, (2) cognitive load – complex software is difficult to understand, and (3) unknown unknowns – complex software can spring the unexpected on us.

Ousterhout covers this big idea in 20 short chapters with frequent reference to a projects that he has run with students repeatedly (including a GUI text editor and a HTTP server) – providing a testbed for reviewing many design choices. He also uses the RAMCloud project as an example, as well as features of Java and the UNIX operating system. This makes a refreshing change from artificial examples.

To decrease complexity requires developers to think strategically rather than tactically which goes against the flow of some development methodologies. Ousterhout suggests spending 10-20% of time on strategic thinking – this will pay off in the long term. He cites Facebook as a company who worked tactically and Google and VMWare as companies who worked more strategically.

At the core of reducing complexity is the idea of “deep modules”, that’s to say systems that have a relatively small interface (the width) which hides information about a potentially complex process (the depth). The Java garbage collector is the limiting case for this – having no user accessible interface. The aim of the deep modules is to hide implementation details (information) from users whilst presenting an interface that only takes what is required. This means deciding what matters to the user – and the best answer is as little as possible.

This goes somewhat against the ideas of the Agile development movement, as expressed in Clean Code by Robert C. Martin (which I read 10 years ago) – who was a big fan of very short functions. I noticed in my review Clean Code that I have some sympathy with Ousterhout’s view – small functions introduce a complexity overhead in function definitions.

Also on the theme of Agile development, Martin (in Clean Code) sees comments as a failing whilst Ousterhout is a fan of comments, covering them in four chapters. I recently worked on a project where the coding style was to rigorously exclude comments which I found unhelpful, that said I look at my code now and see orphaned comments – no longer accurate or relevant. The first of Ousterhout’s chapters on comments talks about four excuses to not provide comments, and his response to them:

  1. Good code is self-documenting – some things cannot be said in code (like motivations and quirks)
  2. I don’t have time to document¬†– 10% of time on comments will pay off in future
  3. Comments get out of date and are misleading – see later chapter
  4. The comments I have seen are useless – do better!

The later chapters focus on the considered use of comments – thinking about where and what to comment rather than sprinkling comments around at a whim. The use of auto-documentation systems (like Sphinx for Python) is a large part of realising this since they force you to follow standard formats for comments – typically after the first line of a function definition. Comments on implementation details should be found through the body of a function (and definitely not in source control commit messages). He also introduces the idea of a central file for recording design decisions that don’t fit naturally into the code. I include the chapter on “Choosing names” under “comments” – Ousterhout observes that if you are struggling to find a good name for something there is a good chance that what you are trying to name is complex and needs simplification.

Certain types of code, Ousterhout cites event-driven programming, are not amenable to producing easy to understand code. He also dedicates a chapter to handling errors – arguing that errors should be defined out of existence (for example deleting a file that doesn’t exist shouldn’t cause an error, because the definition of such a function should be “make sure a file does not exist” rather than “delete a file”). Any remaining exceptions should be handled in one place, as far as possible.

There is a chapter on modern software development ideas and where they fit, or don’t, with the central theme. Object-orientation he sees as good in general, with information hidden inside classes but warns against over use of inheritance which leads to complexity (just where is this method defined?). He also comments that although design patterns are generally good their over-application is bad. He is in favour of unit tests but not test-driven development. This seems to be related to his central issue around Agile development – it encourages tactical coding in an effort to produce features rapidly (per sprint). He believes Agile can work if the “features” developed in sprints are replaced with “abstractions”. He doesn’t like Java’s getters and setters, nor its complex serialisation system which requires you to setup up buffering separately from opening a file as a stream – I remember finding this puzzling.

I enjoyed this book – it provides some support for continuing to do things I currently do although they are a little against the flow of Agile development and food for thought in improving further.

Book review: The Mythical Man-month by Frederick Brooks Jr.

mythical-man-monthNext up The Mythical Man-Month: Essays on Software Engineering by Frederick Brooks Jr.

This is a classic in software engineering which I’ve not previously read, I guess because it is more about software project management rather than programming itself. That said it contains the best description I have seen as to why we love to program, it is a page long so I won’t quote it in full but essentially it divides into 5 parts.

  1. the joy of making things;
  2. the joy of making things which other people find useful;
  3. the joy of solving puzzles;
  4. the joy of learning;
  5. the joy of working in such a malleable medium;

The majority of the book was written in the mid-seventies, following the author’s experiences in the previous decade, delivering the IBM OS/360 system. This means it reads like Asimov’s Foundation in places, dated technology, dated prose, but at the same time insightful. This is the 20th anniversary edition, published in 1995 which includes 4 new chapters tacked on the end of the original book. Two of these – No Silver Bullet and No silver Bullet – refired are a couple of essays from the eighties around the idea that there are no silver bullets to making software production greatly more efficient – this is in the context of hardware improvements which were progressing at unimaginable speed – Brooks was looking for routes to similar evolution in software development.

The other two new chapters are a bullet point summary of the original book and a retrospective on the first publication. The bullet point summary chapter removes the need for my usual style of review!

The core of the book is the observation that large software projects frequently fail to be delivered as scheduled. There then follow some chapters on addressing this issue. The Mythical Man-Month chapter is the most famous of these, it essentially says the enticing idea of throwing more people at a problem will speed up delivery is wrong. In some cases this is trivially true – you may have seen the example from the book that two women do not produce a baby in 4.5 months rather than 9 months for a single woman. The reason increasing team numbers for software development similarly fails is the cost in time of effective communication between more people, and the cost in time of onboarding new people. Despite our knowledge we still routinely under-estimate programming tasks, largely through mis-placed optimism.

As mentioned above, The Mythical Man-Month is quite dated. The anachronisms come in several forms, there is the excitement over computer text-editing systems – a revelation at the time of OS/360 was being developed. There is a whole chapter devoted to memory/storage usage which I am pretty sure is no longer a concern except in a few niche cases. There is quite a lot of discussion of batch versus time share systems, from a time when there were one or maybe two computers in a building rather than one on every desk, even one in every pocket. There are role anachronisms, where a team has two secretaries and a "Program Clerk" whose role it is to type stuff into the computer!

There are some places where Brooks describes practices which sound quite modern but differ slightly differently to the current sense. So "architecture" in his parlance is more about interface design than "architecture" as we would describe it now. There is some pair-like programming but it has a leader and a follower rather than equals. Agile is mentioned but not in the modern sense.

I was interested to read Brooks disdain of flowcharts. I remember learning about these – including proper stencils from my father – a programmer trained in the early sixties. Brooks argument is that the flowchart is useful for programming in low-level languages like assembler but not useful for high level languages – particularly those using the "structured programming" approach which was new at the time. Structured programming replaces the GOTO statements found in earlier languages with blocks of code executed on if – then – else conditions and similar.

In a chapter entitled Plan to throw one away Brooks talks about the inevitability of the first iteration of a product being thrown away to be replaced by a better thought out version although he caveats this a little by allowing for progressive replacement. He notes that maintenance costs can be 40% of original cost and each new version fixing bugs has a 20% chance of introducing new bugs. This means the progressive replacement approach is a losing game.

In some ways this book is depressing, nearly 50 years after it was written software projects are still being delivered late with great regularity. On a more positive note I believe that the widespread availability of web APIs and online module libraries (such as PyPI for Python) can produce the sort of large uptick in programmer productivity that Brooks’ felt was out of reach. Perhaps this will not be seen as a productivity boost since it simply means the systems we aim to build are more complex and the number of lines of code measure of code does not capture the complexity of external libraries. The consistent user interfaces provided by Mac OS and Windows are also something Brooks was looking for in his original publication.

Is The Mythical-Man Month still worth reading? I’d say a qualified "yes", the issues it describes are still pertinent and it draws on quantitative research about teams of software developers which I believe will still be broadly relevant. It is a relatively short, easy to read, book. It gives a glimpse into the history of computing. On the downside, much of the incidental detail is so far out of date to be distracting.

Book review: The Earth Transformed by Peter Frankopan

frankopanIt is rare that I am menaced by the sheer size of a book but The Earth Transformed by Peter Frankopan has done this to a degree. The Silk Roads, by the same author is similarly massive. So in a break from my usual habit I am going to review as I read.

The book is about the interplay of climate and humanity, and how humanity impacts the environment with an attempt to cover history across the world rather than focussing on Western Europe.

The extensive footnotes for this book are found in a separate downloadable pdf.

0 – Introduction – Frankopan is a year younger than me – born in 1971, and his early memories were shaped by news reports of acid rain, the fear of nuclear winter and Chernobyl – all stark demonstrations of man’s potential impact on the environment.

1 – The World from the Dawn of Time(4.5bn-7m BC) – The earth’s environment has always been changing, in deep time there was a much lower concentration of oxygen in the atmosphere. Those animals we see around us are the result of evolution through multiple cataclysmic environmental events.

2 – On the origins of our species (7m BC-12,000BC) – Climate change in central Africa and growing social groups led to speciation of the hominid group. We started large scale manipulation of the environment – managing forests with fire – 65,000 years ago.

3 – Human interactions with Ecologies (c.12000-c.3500BC) – End of the Younger Dryas and the start of the Holocene is a key point for civilisations, the climate becomes more benign and stable and larger settlements start to grow.

4 – The first cities and trade networks (c3500-c2500 BC) – the first cities are founded, and arguably the first anthropogenic climate change takes place. With cities came hierarchies, ownership and vulnerability to shocks and disease.

5 – On the risks of living beyond one’s means (2500BC-c.2200BC) – One such shock is the great drought of 2200BC, often seen as a global phenomena but actually rather complicated with different regional effects and an impact which was perhaps most obvious on the ruling class.

6 – The first age of connectivity (c.2200-c.800BC) – the environment provides resources unevenly, and so trade is necessary as societies become more sophisticated, these trade networks lead to interdependence so when one society falls others are impacted. The trade is not just in goods but also in ideas.

7 – Regarding Nature and the Divine (c1700-c.300BC) – Religions which we still see today arose several hundred years BC, and many of them made references to the environment. The ruler was often an intermediary to the gods/control of the weather – rain being particularly important. Even in this time there were exhortations to preserve the environment.

8 – The Steppe Frontier and Formation of Empires (c.1700-c.300BC) – the Eurasian steppes provided a catalyst for the growth of empires in the neighbouring region, alongside the domestication of the horse in about 3000BC. This combination provided rapid transport, and the flatness of the terrain made expansion easy. There is also an interplay between nomadic and pastoral peoples.

9 – The Roman Warm Period (c.300BC-AD c.500) – the Roman Empire grew at a time of benign and stable climatic conditions – and fell when those climatic conditions changed. Contemporary writers noted the pollution in Rome and other big cities. We can see the lead of the Roman Empire in Greenland ice cores.

10 – The Crisis of Late Antiquity (AD c.500-c.600) – the decades from 530AD saw multiple volcanic eruptions leading to global cooling, food shortages, and the rise of disease (the Justinian plague) and the fall of empires.

11 – The Golden Age of Empire (c.600-c.900) – the Prophet Mohammad’s agreement with the ruling elite in Mecca in 628AD provided an Arab identity that grew to an Empire stretching across North Africa and into Spain. Trade grows with sub-Saharan Africa. These patterns are replicated in the Americas and the Far East. Literacy grew in the eighth century with the introduction of paper from China. Empires started to decline in the 9th century as another warmer drier period started.

12 – The Medieval Warm Period (c.900-c.1250) – the Medieval Warm Period was both warm, and stable with unusually low levels of volcanic activity. During this time there was a large growth in global population, and Northern Europe saw significant growth. This growth was a result of improvements in crops and technology, as well as the benign climate.

13 – Disease and the formation of a New World (c.1250-c.1450) – the 13th century saw the rise of the Mongol empire, under Genghis Khan, stimulated by wetting weather in the steppe leading to more productive pasture when other areas were suffering drought. But the wet weather and the extensive trade networks of the Empire led to the rise of Black Death. Interesting parallels between post-Plague and post-1918 influenza Europe – the roaring twenties.

14 – On the expansion of Ecological Horizons (c.1400-c.1500) – the 14th and 15th century saw the fall of some of those empires that rose during the earlier more benign and stable weather, more driven by the instability of large empires than by climate change. It also saw the European "exploration" of the world and the large scale transport of plant and animal species across the world.

15 – The Fusion of the Old and the New Worlds (c.1500-c.1700) – the European "discovery" of the New World introduced a massive migration of flora and fauna around the world, potatoes, tomatoes,chillies from the New World to the Old. Pigs, sheep, goats and cattle from the Old to the New.

16 – On the exploitation of Nature and People (c.1650-c.1750) – the new sugar, tobacco and cotton industries required a large workforce, resistant to malaria, and Africans fitted the bill – this chapter to about slavery.

17 – The Little Ice Age (c.1550-c.1800) – the Little Ice Age has long been known but its magnitude was quite variable around the world, many things have been ascribed to the Little Ice Age but connections and causality are tenuous. The 17th century saw significant developments in military technology and spending on professional armies in Europe. There was also a large rise in urbanisation. Variable weather, uncertain crops hit some countries hard.

18 – Concerning Great and Little Divergences (c.1600-c.1800) – 1600-1800 was the period in which the economies of Europe diverged from those of Asia and Africa, and in Europe the North pulled away from the South. The introduction of the potato to Europe was important, as was maize and manioc (cassava) to Africa.

19 – Industry, extraction and the Natural World (c.1800-c.1870) – markets became truly global with wheat from North America cheaper to ship from Canada to Liverpool than from Dublin to Liverpool. Colonialism was at its height with Britain leading the world and the Americans expelling indigenous people from their own lands.

20 – The Age of Turbulence (c.1870-c.1920) – new resources became ripe for exploitation like rubber, guano and tin. Industrialisation proceeded apace. Concerns about climate began, and the Carrington Event and the Krakatoa eruption started scientists thinking about global impacts. Global pandemics made an appearance for both people and animals.

21 – Fashioning New Utopias (c.1920-c.1950) – the middle years of the 20th century saw a new wave of exploitation with oil, copper, uranium and more recently lithium becoming important resources. Colonialism receded but was replaced by corporate and government interference in states. In the Soviet Union ecological damage, and great human upheaval was driven by the dash to modernise but in a communist rather than capitalist framework.

22 – Reshaping the Global Environment (the mid-Twentieth Century) – the USSR and the USA started large scale environmental modification projects, see Teller’s proposals to use nuclear explosions to change just about anything.

23 – The Sharpening of Anxieties (c.1960-c.1990) – in the sixties the USA and USSR got heavily into weather modification, and the Americans into Agent Orange in Vietnam. The USA programme was conducted in deep secrecy, and when it was revealed there was an outcry which lead to a treaty banning such environmental modification. This led to a wider thaw of Cold War interactions.

24 – On the edge of Ecological Limits (c.1990-today) – the 1990s saw the fall of the Soviet Union and the rise of Industrial China. It also saw the discussions over climate change heating up.

25 – Conclusions – Frankopan’s conclusion is rather gloomy, he highlights how we are failing to act on climate change but then points we may suffer worse consequences from volcanic activity, or an asteroid strike!

There are themes across the whole book, in the environment we see periods of stable climate interspersed by periods of change – particularly driven by volcanic eruptions. From the human side we see the growing scale of civilisations, larger civilisations with more connections are more vulnerable to instability and the fall of other civilisations. We see ever increasing urbanisation and exploitation of the environment at ever greater scale.

Although initially intimidating, I found The Earth Transformed rather readable – perhaps because I saw each chapter as a separate essay.

Leaving Address

suit-collageAs of 5pm this afternoon I will no longer be working at GBG.

Since the pandemic leaving a company has been a subdued event with many slipping off into the night, scarcely noticed. This morning I had a final standup with the Data Science Team who shared the card everyone had written in and your gift.

I wanted to write down my thoughts on leaving, and to thank everyone for making my time at GBG – nearly 8 years – an enjoyable one.

I am not mentioning any names for reasons of my failing memory, and GDPR, a subject of which I have surprising knowledge – I first sat in GBG in the Compliance team which was at the time named differently and was rather more diverse in its members.

In my career I have been a university lecturer, a research scientist at Unilever, a data scientist at a start-up and finally a data scientist at GBG. I have been used to working in environments full of scientists. GBG represented quite a dramatic and refreshing change for me. I have enjoyed meeting and chatting to you all. It turns out I even enjoyed talking to potential customers – something I had not done before.

I have sat in the Chester office, in pretty much the same place, for my entire time at GBG with a slowly changing cast of characters. It was a spot where we could watch the world go by, occasionally seeing cars driving into the ornamental lake. When lockdown came we migrated to a Teams channel called “The Lonely Aisle”. My aisle mates hold a special place in my heart.

It will surprise many to learn that previously I have not been known for my collection of flamboyant suits, I think everyone will know what I am talking about here! I have always worked in environments which either didn’t have a company Christmas party or I didn’t attend. All I can say is that for one Christmas party my watch recorded 13 miles of dancing! I have illustrated this post with a collection of photos of me, in my suits, which feels a little odd but I have so few pictures of you.

I was given the Property Intelligence dataset to create on my first day in GBG by the Business Unit leader, and working on it will be the last thing I do as I leave. It was with some sadness I sent the email marking the end of the most recent build to the Product Manager.

The Dave’s from the Chester Production team have been a fixture throughout my time at GBG and I have enjoyed working with them all. “The Dave’s” does not count as revealing names since it is the law that members of the Production team are Dave even when they aren’t.

I would like to thank all my line managers at GBG, in retrospect I realise that I considered them “keepers” who had been assigned to me somewhat arbitrarily for bureaucratic reasons. I generally took what they considered to be directions as suggestions. This attitude may have led to some friction on occasion but I enjoyed our contractually required meetings.

It has long said on my blog that “[I work at] GBG where they pay me to do what I used to do for fun!”. I enjoy playing with data and computers, I have done since I was about 10. GBG actually paid me to attend meetings and do other things I did not enjoy. My play may not seem commercially relevant however it means I am in good position to address a wide range of urgent issues at short notice and I also made a bunch of interesting prototypes including voice input for address lookups, and the notorious Edited Electoral Roll in Elasticsearch experiment which probably marked my cards with Compliance – amongst many others.

It has only been in the last year or so that I have worked in a team of data scientist, prior to this I was a lone wolf or perhaps a rogue elephant. It was nice to work in a team where we could learn new things together.

I am not leaving voluntarily and the process of my departure has been stressful, for more than just me. I have been really touched by the support of my friends at GBG, and the wider Linkedin community, during this difficult time. If I can make one recommendation for those experiencing redundancy it is “Don’t suffer in silence”.

I go now to a better place! I know it is difficult to believe but it looks like I might actually be able to retire. I don’t think this is what I will do but I will take the summer off – the last before my son goes to high school. Then I will be looking for consulting style work. I welcome your thoughts on this, I’m not really prepared for retirement.

I am available on a wide range of social media platforms, so stop by and say hello.

Book review: Masterminds of Programming by Federico Biancuzzi and Shane Warden

mastermindsThe next review in my work related books thread is of Masterminds of Programming by Federico Biancuzzi and Shane Warden. The subtitle, Conversations with the creators of major programming languages, is a good summary of the contents. The book is an edited transcript of interviews with the creators of major programming languages.

Frequently the conversation is with a single person but in a couple of cases two or even three people are interviewed. This is one small failing of the book because particularly where they interview three people the resulting chapter is very long and a bit repetitive.

There is a valid question to ask as to whether languages can be so closely tied to single individuals, and in the afterword the authors touch on this saying that one of the recurring themes was that the people they interviewed succeeded because they surrounded themselves with brilliant people. Some of these languages started off as one-man exercises but most grow from collective academic or corporate efforts, and even the one-man band languages developed a fairly formal community.

The languages covered are object-oriented languages (C++, Objective-C, Java, C# and Eiffel), functional languages (ML, Haskell, APL), glue languages originally designed to occupy the space between Unix and C (Awk, Lua, Python, Perl), languages designed for embedding (Forth and PostScript). Dartmouth Basic, SQL and UML are basically their own things. To be honest UML does not really fit into the book in my view since it is a formal design description language rather than an executable programming language. The languages were created between 1964 (Dartmouth BASIC) or maybe 1957 (for APL) and 2000 (C#).

I was sad to note the absence of a chapter on FORTRAN but John Backus, the inventor of FORTRAN died in 2007 – a couple of years before the book was written. Also there are no women interviewed in this book, a quick search reveals there are a number of programming languages invented or co-invented by women. COBOL, invented by Grace Hopper would be a prime candidate here but she died in 1992. Small Talk which inspired a lot of object-oriented languages was co-invented by Adele Goldberg and LOGO co-invented by Cynthia Solomon would fit rather well into the book.

The interviewers clearly had a set of questions which they asked each interviewee and the varying results indicate which questions chimed with the interests of the interviewee. The topics included concurrency, how to manage feature requests for languages, working in teams, debugging, software engineering and teaching.

The authors of the object-oriented languages (C++, Objective-C, Java, C# and Eiffel) are somewhat at each others throats. However, they are all pretty clear that object-orientation is the way forward for large software projects although they see encapsulation rather than inheritance or reuse as the key benefits it brings. There is a degree of condescension towards those languages that they perceived to have been successful as a result of marketing.

The authors of the functional programming languages are more interested in formal specification, I feel I should learn more about type theory. I have looked at Haskell in the past, and found it a bit challenging, however ideas from Haskell and other functional programming languages have made it into Python, my preferred language. The chapter on APL was entertaining, it was conceived and developed as a coherent formalised system for describing algebra the authors did not touch a computer for a number of years after “development” started in the mid-fifties. It is written as symbols which are challenging to enter on a conventional keyboard, you can see it in action here.

Tedd Codd’s relational database design was core to the success of SQL, and is largely why it has not been replaced. SQL was designed alongside IBM’s System R but Oracle produced the first commercial SQL engine.

I learnt a few random facts from the book which I can’t write as a coherent story:

  • Charles H. Moore – author of Forth: “Legacy code may be the downfall of our civilisation”;
  • Awk is an acronym of its authors names, Alfred Aho, Peter Weinberger and Brian Kernighan;
  • Tom Love – co-author of Objective-C – “100,000 lines of code fills a box of paper and requires 2 people to maintain it. Test cases should be another two or three boxes.”!

The book would have really benefited from some sample code in each language, perhaps in the manner of Exercises in Programming Style which implements the same algorithm in different programming styles. I picked up Beautiful Code by Andy Oram and Greg Wilson, interviews with programmers, for my reading list. As well as The Mythical Man-month by Frederick P. Brooks, Jr which I probably should have read years ago.

I found this book really interesting, in part as a way of understanding how the programming languages I use every day of my working life came into being but also to understand the mindset of highly skilled programmers.