Reflections on Writing Over Half a Million Lines of Go at Khan Academy

In December 2019 the author began the Goliath project, migrating Khan Academy's backend from Python 2 to services written in Go, introducing necessary changes for the transition.

At the start, no team member knew Go; through experiments they proved Go was a better choice. Today all backend and full‑stack engineers write Go, with over 500,000 lines in production, prompting a reflection on the language.

1. Engineers Love Go

Engineers describe Go as easy to read and write, and they appreciate its error‑handling model that returns error values. One veteran .NET developer praised being able to call functions that never return errors when they succeed. Others admire the standard library (e.g., io.Writer) and the excellent tooling—fast compilation, built‑in formatting, and reliable module management such as gqlgen.

2. We Want Generics, Otherwise Go Feels Verbose

While most code works without generics, many engineers miss them, especially when writing internal libraries or handling slices. The lack of generics is the most common complaint, and the Go team's effort to add generics has been well received. Engineers are excited about the upcoming release, expecting it to reduce boilerplate and enable higher‑order functions, with the new slice package cited as a promising addition.

3. Performance and Concurrency

Comparisons with Python show Go’s superior performance: a class of 1,000 students loads in 4 seconds with Go versus 28 seconds in Python, and data‑store warnings that occurred hourly in Python are almost nonexistent in Go. The team also leverages Go’s concurrency features; although channels are notable, they often use the sync package more heavily.

4. Thoughts After Writing 500 K Lines of Go

In summary, Go is more verbose than Python but the team loves it for its speed, reliable tooling, and production stability. Engineers come from diverse backgrounds, leading to varied perspectives, yet they all agree that Go has fulfilled the goals of the Goliath project, and they thank the Go community for its continued development.

Original article: https://blog.khanacademy.org/half-a-million-lines-of-go/