With its recent update, WildFly Swarm has been renamed Thorntail. A among developers, the name of WildFly Swarm is still commonly used. WildFly Swarm represents an excellent approach to create deployables for Java EE Microservices. WildFly Swarm stands on the shoulders of a WildFly Application server, which itself stands on the shoulders of one of the most famous names in Java EE world: JBoss. As explained in first section of this chapter, runtimes for Microservices in the Java EE world, be it any product (including Spring Boot), are only repacked application servers with just enough of the runtime dependencies the actual application requires. Additional services, plugin support, cloud integration, and available support make all the difference. And WildFly Swarm offers an excellent package.

The release cycle of WildFly Swarm is considerably faster than a full-blown WildFly Application service. There are monthly updates to be found, not only containing bug fixes, but coming with many improvements and support for new features. In general, WildFly is evolving very rapidly. In the MicroService environment, the WildFly swarm makes it easy to use an application throughout different environments, as it automatically configures thread pool sizes at startup based on available resources. At startup, a message revealing the actual configuration can be found:

Worker 'default' has auto-configured to 16 core threads with 128 task threads based on your 8 available processors.

In this case, WildFly detected eight physical cores with 18 threads available, resulting in 128 threads available in the default pool. This way, neither developers nor administrators have to worry about resource allocation configuration, as the application is deployed in vastly different environments.