State Management in Stream Processing: How Apache Flink and Kafka Streams Handle State

The $50 Million State Problem

Your real-time fraud detection system processes 200,000 transactions per second. Each transaction requires checking against the customer’s last 100 purchases, current spending velocity, and location patterns. That’s 3.2 GB of state per second. A single pod crashes. Do you lose everything and start cold, triggering false positives? Or do you recover instantly with zero data loss? The difference costs $50 million annually in fraud that slips through during cold starts.