Performance Optimization
Experiences focused on system performance improvements.
APIs Slowing Down After Deployment: Improving JVM Cold Start Problem by 85%
Introduction Recently, our team migrated from a Docker Compose-based production environment to Kubernetes. It was a choice to properly utilize features needed in an MSA environment, such as scalability, automation, and zero-downtime deployment. Related article: From No Dev Server to GitOps: My Journ...
November 18, 2025
Money Disappeared? Transitioning Account Balance Verification Batch from Tasklet to Chunk & Partitioning
Hello. I’m Jeong Jeongil, a 2-year backend developer working at a lending and investment platform. While internally verifying data consistency in our operational company service, we experienced account balance and internal Point inconsistencies due to transaction processing time and batch work ineff...
December 24, 2024
External API Performance Improvement: Reducing Response Time from 5100ms to 57ms with Look-aside Cache
Hello. I’m a 2-year backend developer currently working at a lending and investment platform. In this post, I’d like to share my experience of improving external API performance using the Look-aside cache pattern. The problems I faced during this process were not simple. Various issues were intertwi...
December 16, 2024
Creating a Common Excel Download Utility Class Using Java POI
It’s nothing grand, but I’d like to share an experience I had at work a few months ago. It started with inquiries from end users, namely my coworkers, who use the back-office system internally. The inquiry was as follows: Excel download doesn’t work or becomes strange when the row count exceeds a ce...
November 19, 2023