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#spring-boot

2 stories

Banner: an API gateway sending requests to crossed-out service instances still listed in a registry

Networking & DNS Bug Report

API gateway kept routing to dead instances: Eureka self-preservation and stale caches

John Nguyen · Jun 10, 2026 · 8 min read

After a spot node reclaim, our Spring Cloud Gateway sent traffic to instances that no longer existed for over six minutes. Eureka had entered self-preservation and stopped evicting, while three layers of caches added their own delay. Here is how we cut stale routing to seconds.

Banner: a Java list being edited by one hand while another hand iterates through it

Programming Languages Bug Report

Java ConcurrentModificationException removing from an ArrayList in for-each

Daniel Tran · May 13, 2025 · 8 min read

Our webhook dispatcher threw ConcurrentModificationException a few times a day and silently skipped deliveries the rest of the time. Two bugs shared one list: removal inside a for-each loop and an admin thread editing it concurrently.