Thursday 16 February 2017

On Golang and Maintainability

I have talked a bit before, mainly in this post, about how Golang as a language tends to expose complexity and excludes some features that while useful can serve to hide complexity. In this post I'm going to explore this topic in more depth and explain why I think this contributes to Golang being a language better suited to writing maintainable code than Python.

Any sufficiently advanced technology is indistinguishable from magic - Arthur C Clarke

Where Python favours the implicit, Golang favours the explicit. And, where Python hides complexity in 'magic' language features, Golang forces you to go the long way round. Some language features in Python that I consider suitably magic are: decorators, properties and list comprehensions. Decorators and properties are mechanisms of indirection, and all these listed features provide handy shortcuts for developers. List comprehensions themselves are fine but nesting or using them for their side effects can quickly result in difficult to read code.

 Short cuts make long delays - Frodo Baggins

The interactive capabilities of the python interpreter can encourage a user to build up multiple lines of Python code into a single complex expression. Case in point, nested list comprehensions, these are usually the result of the condensation of a couple of loops into a one line wonder. And, programmers tend to love one line wonders, they exude elegance, and removing all those lines makes you feel warm and fuzzy inside, because readability and conciseness are easily confused.

Given the fact that it took some thought and tinkering to determine how to compress some readable for loops into such a concise representation, it is likely that the next person to come along, in the absence of the context of the expression's formation, will struggle to decode the compressed representation. In fact they may even try and rewrite it long-form in order to unravel its secrets. List comprehensions that are used for their side effects are full of even more implicit nastiness.

Maintainability comprises a number of factors but a key one is the ability of another programmer (or even you!), to come along and understand the intention of your program. Readability is not inversley proportional to LoC (number of lines of code), mistakenly in this belief programmers can be inclined to do things in complex rather than intelligble ways. The problem is that it can be difficult to distinguish the two. Perhaps a misunderstanding of the code is a indicator of a flaw of the reader or perhaps it is because a simpler representation would suffice. In the former case the writer could be forced to writing a lowest common denominator. In the latter case it pays to consider a language feature's potential cost as well as its benefits.

Language features are like power tools, we come up with excuses just to use them

Golang forgoes many shortcut features resulting in more explicit and maintainable code. I have found that whilst no means necessary, static typing also helps manage complexity and thus improve maintainability in a large application. And optimising for maintenance can be a good idea as this is often where we spend most of our time as developers.

Monday 6 February 2017

Improvements in go 1.8

This post represents notes collected on the new go release and from the state of go talk of Feb 2017, on changes in go 1.8.

Video of the talk can be found here.
Slides of the talk can be found here.

 General Improvements

  • ignore struct tags in type conversions (easier type conversions)
  • 32-bit mips support
  • osx 10.8+ supported
  • go 1.8 is last version to support ARMv5E and ARMv6 processors
  • go 1.9 will require ARMv6K 
  • go vet (sort of compiler warnings) now detects closing http.Response.Body before checking error
  • default gopath $HOME/go on unix
  • go bug command opens a bug on with version/machine information
  • Compiler backend improvements (SSA) sees cpu usage reductions of 20-30% on arm and upto 10% on x86 (SSA was already part-implemented on x86).

 Performance Improvements

  • build times faster than go 1.7 but slower than go 1.4
  • improved -race detection
  • mutex contention profiling `go test bench=. -mutexprofile=mutex.out`, can provide data on whether you should lock in a less or more granular manner, sequential could even be faster.
  • sub-millisecond (~100 microsecond) GC pause times, costing an extra 1/2% cpu.
  • defer is a 1/10th to a 1/3rd faster, but still not that fast, for example...
  • cgo is 50% faster, mostly due to removing high frequency defer calls

Additions to the Standard Library

  • sort.Slice() introduced, provides easier slice sorting
  • plugins introduced (linux only linux atm), load shared libraries at runtime, enables hot code swapping
  • added Shutdown method to http.Server, was previously very hard to stop previously, personally I had to resort to
  • HTTP/2 support introduced

Full go 1.8 release notes are here.

go 1.8 is set to be released on February 16th 2017.

Golang UK conference is on August 16th to 18th 2017.

Friday 3 February 2017

Thoughts on Two Years in Golang

In my last post, I talked/ ranted a little bit about not being swept up in new trends or languages without proper analysis of their pros/cons and suitability for use in certain scenarios. Hence after having learnt Golang from scratch two years ago and having been programming in it day in day out its about time that I collected my thoughts on it.

Now a lot can be said about the cost of learning a new language, that time spent learning the basics, making the right of passage mistakes and getting up to speed with the tooling. However, I think that Golang recognises these costs and does what it can to mitigate these for a new developer, not to say that there isn't still a cost. But, I know that for many companies, mine included, the ease at which a Golang programmer can be converted is a signifcant consideration in the choice of the language.

C and Python had a love child and they called it Golang

Strict, opinionated and boring

I think of Golang as a strict, opinionated and boring language. Now, I know that the word 'boring' has many negative connotations. But when I invoke it here I mean that it lacks many of the features that tittilate academics and occupy the minds of advanced programmers. I discussed the exclusion of exceptions in a previous article. Other non-existent features include some I miss: Generics, operator overloading, primitive sets, assertions. And some I don't: nested functions, inheritance.

I have often heard people say Golang ignores the last X years of language development. Of course there are some useful features missing but in order to keep the language small and simple you have to be strict, and evaluate the costs and benefits of adding a new feature. Terseness can be considered as a feature in and of itself. In other languages the plethora of features can be bewildering and take an age to master, with the extra folds hiding more pitfalls and stumbling blocks.

Inheritance is a big ticket item but I have found that Interface gets you most of the benefits of duck typing without dragging in the massive amount of complexity and metadata fiddling inheritance brings.

Golang has some really nice features. Goroutines are great, these are lightweight concurrency primitives, basically multiplexing upon threads. There are also channels for communicating between goroutines. It is really great that Go can do concurrency so well out of the box and I find it much more clear than Python's generators.

Importantly Golang is very quick to compile and run, out-performing C Python easily and many other Python implementations. This is an oft cited reason for switching from Python to Golang. Most of my work with Golang has been on embedded devices and this was the reason Python was never in the running. There were concerns about its GC (Garbage Collection) latency but great work has been done to bring this to sub-millisecond levels in go 1.8

It has nice concise syntax, something akin to a cross between Python and C, which is nice as I am fond of Python syntax, Java syntax makes me queasy.


Probably the best feature is the tooling available and the strength of the ecosystem in general, it is fairly comprehensive and has a strong standard library which is something I really miss in Python. It tries hard to get things right the first time and mostly succeeds.

govet and golint are great static analysis tools and gofmt and goimports can format your source code on save in compliance with the style guide, saving time and bikeshedding. Golang really benefits from the strictness here, introduced at such an early stage that everyone is forced to get on board. I am so used to auto code formatting that I also set up auto pep8 formatting in Python and didn't look back.

The source tree layout and the build process are also standardised and there are great tools for running, building, testing and generating coverage stats in a standardised way with very little effort. You get deployable static binaries with little hassle which I always found a struggle with Python. This layout and process is strictly dictated which I know will rub some people the wrong way but in my opinion it saves a lot of turmoil for a little sacrifice in freedom.

It is very easy to pull dependencies `go get`, and you're there. However the lack of versioning and no way of telling how popular a library is are problematic. There are some third party solutions to the former problem, personally I use godep and there was some attempt to fix versioning with vendoring, but I don't feel as this is a complete solution and poses its own questions. However I am always a bit horrified by the multitude of tools when I have to pull dependencies in Python  {pip, easyinstall, setuptools}, I don't think go does too bad in comparison.


Now for some gripes.

Non-pointer receiver methods, this is often a common pitfall for new go programmers. In using a method with a non-pointer receiver, the receiver itself is copied by value meaning that changes to that receiver after the function call are not persisted. See this code example.

Lack of a generic max function, this is quite embarrassing for the language as it is something that newcomers will run into fairly early. Due to the lack of generics there is no max function for all numeric types and seemingly as a result of this no max function for any numeric type, err, yea, I know.

Sensible slicing syntax, now the syntax we have is quite nice for some use cases and is appreciated but I still have to resort to slice tricks.

Being strict and opinionated has downsides, on some issues the exclusion of certain features and lack of support for certain use cases makes it seem as though some problems are being wilfully ignored, namely, generics and dependency versioning.


I find Golang a great place on the ladder of abstraction, garbage collected and static typed. I can develop faster in Python but I am more confident of my Golang code's correctness as Python hides complexity, tries to be smart and lacks the safety of the compiler. However Golang does lack some of the libaries and stacks for widespread adoption on the server though this is improving everyday. And its memory requirements may be too demanding for some extremely resource constrained embedded environments, however it has performed admirably for our embedded use case thus far. After two years I like Golang as a language, there's much much more that I have to say about it. But it suffices to say that its a language that I am now very comfortable with and productive in and I feel more confident writing maintainable and efficient code in than Python.