How I became a Go developer

How I became a Go developer Luca Panziera - The Financial Times

Who I am Started working for the FT 3 years ago I was hired as Java developer I spent 10 years implementing applications in Java Mainly in computer engineering research projects

Why Java? Java is a popular language: ● Many libraries ● Cross-platform ● Garbage collection ● Memory security

What people were doing at the FT when I joined Implementing the new Content platform Going towards microservices... Each microservice was a Java application running on a VM in two FT data centers and AWS. In parallel… … Implementing a hand-rolled “container orchestration framework”

One day our software architect said... WE MUST USE GO! Why? Go is efficient!... And we can implement everything in few milliseconds!

Let’s take a look at Go…

What is Go? A Programming Language: ● developed by Google ● announced in November 2009 ● Version 1.0 released in March 2012 So… it’s quite new!

What Go developers had in mind? ● Statically typed and scalable to large systems (like Java or C++) ● Simple and readable, without excessive boilerplate ● Not requiring IDEs, but supporting them well ● Supporting networking and multiprocessing

My first reaction to Go import “math” Struct instead of Class?! type Circle struct { x, y, r float64 Methods are functions?! } func (c *Circle) Area() float64 { return math.Pi * c.r * c.r } Is this C?

Why it looks like C? Pointers No overloading: func addInt(a,b int) int { return a + b } func addFloat64(a,b float64) float64 { return a + b } Very basic data structures: Array, Slice, Map... nothing more Go is a compiled language

The reaction of my team... We must use Go! It’s going to make our life! What the hell is this?

Actually Go is really cool! It is more concise… compared to Java… Java public class Circle { private double x, y, r; public double getX() { return x; } public void setX(double x) { this.x = x; } public double getY() { return y; } public void setY(double y) { this.y = y; } public double getR() { return r; } public void setR(double r) { this.r = r; } } public double area() { return Math.PI * r * r; } Go import “math” type Circle struct { X, Y, R float64 } func (c *Circle) Area() float64 { return math.Pi * c.R * c.R }

Go is easy to learn Go Tour + Effective Go After few days

Bit of practice Decent Go developer

CPU and memory efficiency ● Java microservice: JSON manipulation, 9K requests/day, 340MB memory ● Go microservice: Database query + data manipulation, 40K requests/day, 12MB memory Save cost of Cloud Services with smaller VM instances

What about memory allocation?! Memory safety and Garbage collection func brakeSlice() { a := []int{1, 2, 3} a[5] = 7 } panic: runtime error: index out of range

A simple way to handle concurrency func send(c chan string, msg string) { for { c <- msg } } func receive(c chan string) { for { msg := <-c fmt.Println(msg) } } main() go send(c,”gopher”) Goroutine-send go receive(c) c channel ”gopher” Goroutine-receive

No more Maven hell Go is a compiled language so... Fast in compiling and running test (few seconds) A easy import of libraries with “dep” dep init dep ensure -add github.com/sirupsen/logrus dep ensure -update go test ./... go build

Go sounds amazing… but...

When the team started using Go... People forgot about code practices!

Everything in a single file main.go Usage of func: line 34 Usage of func: line 232 Impl. of func: line 476 Usage of func: line 675 Source: wikipedia A good excercise for head bagging

Code in many files… but without any logic! pluto.go user.go Usage of func pippo.go cat.go db.go record.go dog..go pippo.go Where is the implementation of func? meaningless.go Impl. of func

Unit tests were not really mature... Coverage wasn’t great Difficulties in mocking Missing Integration tests Couple of times the worst happened in Production

OMG… What’s the situation now?

The FT Content platform After 3 years... The quality of code base improved a lot A Kubernetes-based platform made of ~150 microservices 85% of them are implemented in Go Reduced cost of 80% on AWS So, Go has been a success for us!

In the world of microservices… Fast implementation from scratch Efficiency with network overhead Go meets this requirements

What I learnt by using Go? Go combines: ● efficiency ● memory safety and garbage collection A concise programming language No language boundaries allow you to write excellent code… or total crap Good sense of the developer is the key (as usual).

Thank you! We are hiring! ft.com/dev/null @izzyblues83 Credit Ashley McNamara and https://github.com/ashleymcnamara/gophers for most images. Credit Renee French for the original gopher concept and design.

How I became a Go developer Luca Panziera - The Financial Times