profile-blocking

Thread starvation in Spring WebFlux is typically caused by blocking calls within reactive pipelines, which tie up limited event loop threads and cause performance degradation.

To find blocking calls in reactive Java code, analyze map and flatMap chains for patterns like .block(), Thread.sleep, and blocking I/O operations that halt the reactive pipeline.

The best way to offload blocking I/O in a WebFlux service is to schedule the blocking work on a dedicated scheduler or leverage virtual threads to prevent thread starvation.

Yes, virtual threads can be used to handle blocking calls in Spring WebFlux, providing a strategy to safely offload blocking work without causing event loop thread starvation.

You should not use .block() in a reactive pipeline within WebFlux controllers or map and flatMap chains, as it halts the reactive stream and causes immediate thread starvation.