Java at AWS: Lessons Learned from Upgrading and Modernizing a Massive JVM Codebase By Yishai Galat

As one of the largest Java users in the world, Amazon has been on a perpetual journey of upgrading Java versions in it's production systems and for the last 7 years also contributed to the evolution of the JVM. In this talk, we will share our experiences and lessons learned from migrating a large codebase running on massive infrastructure from Java 7 to 8, 11, 17, and even 21. We'll cover key technical challenges we faced in upgrading our codebase while maintaining availability and improving performance, including dependencies, observability, and platform compatibility. We'll share which investments paid off, where we're still struggling, and the archaic parts of Java we wish we could leave behind. You'll learn about: The scale and diversity of AWS's internal Java ecosystem How we manage the effort of migrating to Java 17 What hurdles we fixed, jumped over, and which still remain How observability, profiling, and modularization are critical Lessons for modernizing your own large-scale Java backend Coping with device world If you want an inside look at our modernization war stories from the Amazon trenches, come listen to James Gosling who needs no introduction, and Yishai Galatzer, Director of programming Languages in AWS. YISHAI GALATZER Director of programming Languages in AWS. JAMES GOSLING Father of the Java Language