Go is becoming increasingly popular and I find it troubling. It’s taken me quite a while to work out why that is, and quite a few drafts to try and express it in a way that gets my point across in ...

In an ideal world everything would just work fine all the time. However, the real world is rarely like that which means we need to handle failures. Different programming languages have different ap...

The twelve-factor methodology is a pretty solid approach to deploying applications that can run locally and in multiple cloud environments, as well as being able to scale out on demand. We’ve used ...

Akka HTTP’s client uses connection pooling, either implicitly when you use the singleRequest method, or explicitly when using cachedHostConnectionPool or superPool. The number of requests that can ...

When I interviewed for Deliveroo a little over three years ago it was a tiny company so the ‘process’ was just a series of chats with a senior engineer, the CTO, and the CEO. All held in coffee sho...

With functions that can fail, people tend to think there are two possible options, success or failure. This is what’s modelled by Scala’s Try[A] and Future[A] types, as well as plain old try/catch....

Deliveroo is just over four years old and has grown incredibly quickly; we deliver millions of meals every week in 12 countries. When a company is growing at this rate, how do you get leadership, e...

In just two years Deliveroo has expanded from central London to hundreds of cities in twelve countries, and the engineering team has grown at a similar rate. To allow us to continue innovating rapi...

Tracking authenticated user sessions can be implemented in Redis using setex with some serialised JSON. It works pretty well until you have to cope with millions, or even tens of millions of sessio...

Consider a collection of two addresses. #1 was updated at 11:20 and #2 was updated at 11:45. The last modified date of the collection can be the latest time that any individual address was modified...