A thread group in Java is a way to group threads together so that they can be managed as a single unit. A thread group can be used to set common properties for a set of threads, such as their priority or daemon status. The thread group can also be used to control the behavior of the threads, such as interrupting or stopping them.
However, thread groups in Java are considered outdated and are not recommended for use in modern applications. There are several reasons why thread groups should be avoided:
- Thread groups are not very flexible. Once a thread is assigned to a group, it cannot be moved to another group. This can make it difficult to manage threads in large applications.
- Thread groups are not very scalable. Large applications with many threads can quickly become unwieldy if managed using thread groups.
- Thread groups are not very compatible with modern threading constructs such as ExecutorService and CompletableFuture.
- Thread groups can introduce unnecessary complexity and can make the code harder to understand and maintain.
Instead of using thread groups, modern Java applications typically use the ExecutorService framework for managing threads. This framework provides a more flexible and scalable way to manage threads and is better suited to modern applications.