Quarkus provides a core thread pool executor. The Quarkus Javadocs state that this thread pool is responsible for running all blocking tasks. Quarkus also recommends that users create their own thread pools, by obtaining a bean of the ManagedExecutor interface. The implementations of this interface (e.g. SmallRyeManagedExecutor) should support asynchronous execution.
However, when Quarkus provides an instance of ManagedExecutor, this is actually a ViewExecutor. The ViewExecutor uses the core Executor as a delegate. Since it was not clear how asynchronous execution is supported when a blocking tasks executor is used, we decided that it would be better to use a separate thread pool.
- The Camunda Quarkus extension uses its own thread pool, independent of the Quarkus core thread pool.
- JobExecutor config properties are applied through reflection to avoid repetition.
- The Job Acquisition thread runs on the Camunda Quarkus extension thread pool.