Java version 11 does not have fibers, but there are some libraries that support limited fiber handling, and also there is a JDK project (http://openjdk.java.net/projects/loom/) that aims to have a later JVM version that supports fibers. Therefore, sooner or later, we will have fibers in Java and, hence, it is important to understand and know what they are.
A fiber is a finer unit than a thread. A program code executing in a thread may decide to give up the execution and tell the fiber manager to just execute some other fiber. What is the point and why is it better than using another thread? The reason is that this way, fibers can avoid part of the context switch. A context switch cannot be avoided totally because a different part of the code that starts to execute it may use the CPU registers in a totally different way. As it is the same thread, the context switching is...