Daemon thread in Java

A daemon thread can be defined as a specialized service provider thread that offers support and services to user threads. Unlike user threads, daemon threads operate in the background and are primarily created by the Java Virtual Machine (JVM) for executing essential background tasks such as garbage collection and various housekeeping activities. The distinction of being a daemon thread is significant, as it influences the behavior of the Java interpreter. If all non-daemon threads have completed their execution, leaving only daemon threads remaining, the interpreter will promptly terminate.

Daemon threads play a crucial role in the Java runtime environment, ensuring the smooth functioning of background processes and system maintenance activities. By designating certain threads as daemon threads, the JVM ensures that these tasks can continue running autonomously without impeding the termination of the entire Java program.

The concept of daemon threads adds a layer of efficiency and organization to the execution of Java applications. It allows the JVM to manage essential system-level tasks independently, freeing up resources and enabling a more streamlined runtime environment.

Daemon thread has :

  1. Very low priority.
  2. Daemon threads acts as services in Windows.
  3. Only executes when no other thread of the same program is running.
  4. JVM ends the program finishing these threads, when daemon threads are the only threads running in a program.

The setDaemon(boolean) method provides a means to modify the daemon property of a Thread object before it begins execution. By invoking setDaemon(true), the thread is marked as a daemon thread, while setDaemon(false) designates it as a user thread. This flexibility allows developers to control the behavior and classification of threads based on their specific requirements.

Furthermore, the isDaemon() method can be employed to determine whether a thread is classified as a daemon thread or a user thread. When invoked on a Thread object, isDaemon() returns true if the thread is a daemon thread, and false if it is a user thread. This capability enables runtime checks and decision-making based on the daemon status of a thread.

The ability to modify the daemon property of a thread using setDaemon(boolean) and subsequently inspect it using isDaemon() grants developers finer control over the threading model in Java applications. This feature proves invaluable when managing thread lifecycles, coordinating background tasks, and optimizing resource utilization within multi-threaded environments.