Why I wrote the BEAM book (2025)

The BEAM Book grew from a practical need: after years maintaining Klarna’s high-volume Erlang systems, Erik wanted a dependable guide to the virtual machine behavior behind production incidents, including pauses that can disrupt millions of payments. He began writing in 2012, but the project repeatedly stalled amid rewrites, complicated publishing tools, and two cancelled publishing deals. A fresh public GitHub repository in 2017 changed its course: readers contributed corrections and diagrams, offered encouragement, and helped make the work a shared resource. The author’s persistence was driven both by a desire to understand the BEAM in depth and by evidence that other engineers needed a thorough reference.

The book explains how BEAM internals affect real systems, covering scheduling and process management; process memory, garbage collection, and data representation; compilation and execution; tracing and debugging; performance analysis; and the architecture of the runtime. It is aimed at people building or operating Erlang and Elixir applications, especially at scale, who need to diagnose behavior rather than rely on scattered documentation. The account also describes lessons from completing it: protect focused writing time, accept community help, limit scope, and publish a living repository that can evolve with the runtime. After deciding to finish a print edition for a conference deadline, the author declared version 1.0 complete and invited readers to buy it, report errors, or contribute to the open repository.