How to Solve “java.lang.IllegalStateException: block()/blockFirst()/blockLast() are blocking”

Date: 2024-09-19

Java's IllegalStateException regarding blocking operations in Spring WebFlux arises from using blocking methods like block(), blockFirst(), and blockLast() within reactive streams designed for non-blocking asynchronous processing. These methods convert asynchronous streams to synchronous ones, causing performance bottlenecks or deadlocks. Solutions involve avoiding these methods and using asynchronous operators like subscribe() to process elements non-blockingly, maintaining the efficiency and scalability of reactive applications. Properly handling this exception is crucial for optimal reactive programming in Java.

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