A modern application server such as WildFly is a complex beast to conquer. It comprises multiple subsystems, many of which are projects in their own right, and as such have their own project lifecycle. Many of them you may already recognize as they are well-known open source projects. Keep in mind that, when you try to resolve a performance issue with WildFly, it may not be enough to look at the Wildfly documentation; you many need to dig further and look at the subprojects documentation.

Several of the subsystems that have not been addressed in this chapter are so important that they have been discussed in their own dedicated chapters. They are as follows:

Starting from the next chapter, we will go through the various performance settings and design tips for EJB3 in WildFly.