Introduction
In the last couple of weeks I had the chance to explore Jepsen, a framework used for testing distributed systems. Jepsen cannot prove the correctness of some distributed system but rather takes an approach of finding inconsistencies. Deep in the core, it uses txn dependency graphs as described in the Adya’s PhD thesis.
Clojure
Jepsen is written in Clojure, functional language that is bidirectionally compatible with Java. One of the most important characteristics of Clojure is its functions. Functions are used as values, you can return them from other functions, compose them or pass them as arguments. Clojure is classical when you consider referential transparency => if you provide functions with same inputs, they will always return the same output.
Jepsen
Jepsen is a testing tool for distributed systems. Its great feature is an ability to inject different kinds of faults in the system. These faults can be on the instance, network, storage any many different levels. It works on binaries which means it greatly mimics production situations.
Presentation
I had an opportunity to present Jepsen to the rest of the Memgraph team. You can find the link here with many diagrams and explanations of how I used Jepsen in reality.