Hongxi Chen

About

Backend engineer with deep experience building event-driven logistics systems (orders, warehouse execution, real-time delivery tracking) using Spring Boot/PostgreSQL/Redis and strong observability (Prometheus/Grafana). Led a zero-downtime migration from monolithic MySQL to a sharded architecture for ~2M users with dual-write, checksum validation, and fast auto-rollback, and has strong security expertise including PostgreSQL RLS for multi-tenant SaaS and robust OAuth/JWT handling.

Experience

Education

Key Strengths

• Designed event-driven logistics backend (orders/warehouse/real-time tracking) with low-latency APIs and reliable async processing
• Resolved lost/duplicated message issues using transactional outbox + idempotent consumers with retries/deduplication
• Built strong observability for distributed systems using Prometheus metrics and Grafana dashboards
• Handled OAuth/JWT token refresh race conditions using single-use refresh tokens, Redis blacklist, and refresh deduplication
• Led zero-downtime migration from monolithic MySQL to sharded architecture for ~2M users using dual-write, checksum validation, and automated rollback
• Implemented multi-tenant security with PostgreSQL RLS + JWT role claims; prevented cross-org data leaks even when application logic failed
• Proactively identified payment webhook race condition causing ~5% misclassified payments; fixed with idempotent updates and DB constraints to prevent revenue loss