Handling High Traffic Loads

I failed my first interview with a company. The reason for my failure was not revealed, but I suspect it was because I was caught off guard by one of the questions. The interviewer asked me to describe an example of handling high traffic loads from my professional experience. While “high load” is a relative concept, I have never faced the issue of insufficient resources. All the issues I have faced with a lack of resources were easily resolved. That’s why I thought I had never worked with “high load” before.

However, I now understand why this happened. I researched the topic and found out that all I had done before in my programming experience was building an architecture that could handle high load easily. I am very enthusiastic about functional programming, where the code consists of simple (pure) functions that depend only on their arguments. This not only makes the code very robust and simple but also multithread friendly.

In addition, I have experience with microservice architecture. We used it in the last three years while rewriting Baja Bikes monolith with loosely coupled microservices in Go. In our case, it was lambda functions, but the Kubernetes shift can be done easily, and voila, we have a scalable system from the bottom.

For some applications, we used CQRS, a practice that helps separate read and write operations by different threads. This, along with the master-slave approach for SQL databases, can be a deal when an application heavily uses SQL databases. When it comes to databases, it’s worth mentioning that both MongoDb and DynamoDb, which are document-oriented databases, have a huge possibility to scale horizontally. To finish with databases, I should mention Cassandra, which has almost unlimited opportunities to scale.

Another approach would include a different type of caching proxy (Nginx, Varnish) - it was so obvious that I forget to mention it. However, one thing that I definitely missed is performance monitoring. While I almost never had an issue with performance, I never had a chance to use it.

Overall, after learning my lesson and reviewing my experience, I feel more confident in case someone asks me that question again.
Am I missing something? Please, let me know in the comments.