Hi,

There is an issue introduced in Spring 4.2.6.RELEASE (used by Spring Boot 1.3.4.RELEASE) which means that it is possible for @async annotated method calls to become blocked. This happens when you have nested @async annotated calls which use the default task executor, and you have a task executor defined in your application context (but not explicitly used).

I have created a proof of concept here https://github.com/foygl/spring-async-problem

I've only tested this with Spring Boot so I'm not sure if this is a wider Spring problem or just an issue with Spring Boot (although I suspect the former). I've replicated this in Spring Boot version 1.4.0.RC1 (i.e. Spring 4.3.1.RELEASE) so this problem still exists in the latest version.

Thanks