In Java, there are two types of threads:
- Daemon Thread
- User Thread
Daemon threads are low priority threads which always run in background and user threads are high priority threads which always run in foreground. User Thread or Non-Daemon are designed to do specific or complex task where as daemon threads are used to perform supporting tasks.
Difference Between Daemon Threads And User Threads In Java
- JVM doesn’t wait for daemon thread to finish but it waits for User Thread : First and foremost difference between daemon and user threads is that JVM will not wait for daemon thread to finish its task but it will wait for any active user thread.
For example, one might have noticed this behavior while running Java program in NetBeans that even if the main thread has finished, the top left down button is still red, showing that Java program is still running. This is due to any user thread spawned from the main thread, but with main thread one don’t see that red dot in NetBeans.
- Thread Priority : The User threads are high priority as compare to daemon thread means they won’t get CPU as easily as a user thread can get.
- Creation of Thread : User thread is usually created by the application for executing some task concurrently. On the other hand, daemon thread is mostly created by JVM like for some garbage collection job.
- Termination of Thread : JVM will force daemon thread to terminate if all user threads have finished their execution but The user thread is closed by application or by itself. A user thread can keep running by the JVM running but a daemon thread cannot keep running by the JVM. This is the most critical difference between user thread and daemon thread.
- Usage : The daemons threads are not used for any critical task. Any important task is done by user thread. A daemon thread is generally used for some background tasks which are not critical task.
The Major Difference between User and Daemon Threads:
|User Thread||Daemon Thread|
|JVM wait until user threads to finish their work. It never exit until all user threads finish their work.||The JVM will’t wait for daemon threads to finish their work. The JVM will exit as soon as all user threads finish their work.|
|JVM will not force to user threads for terminating, so JVM will wait for user threads to terminate themselves.||If all user threads have finished their work JVM will force the daemon threads to terminate|
|User threads are created by the application.||Mostly Daemon threads created by the JVM.|
|Mainly user threads are designed to do some specific task.||Daemon threads are design as to support the user threads.|
|User threads are foreground threads.||Daemon threads are background threads.|
|User threads are high priority threads.||Daemon threads are low priority threads.|
|Its life independent.||Its life depends on user threads.|
Example: Check Thread is Daemon or not
One can make a user thread as daemon thread by using setDaemon(boolean) method. In this example, thread type is being checked (User thread or Daemon thread) by using isDaemon() method. It returns true if it is daemon otherwise it returns false.
Main Thread Is Thread-0 a Daemon Thread: false Is main a Daemon Thread: false User Thread or Non-Daemon Thread
Example: Make Non-Daemon Thread as a Daemon Thread:
In this example, a non-daemon thread is made a daemon using setDeamon(boolean).
Before using setDaemon() method: Is Thread-0 a Daemon Thread: false After using setDaemon() method: Is Thread-0 a Daemon Thread: true
Don’t stop now and take your learning to the next level. Learn all the important concepts of Data Structures and Algorithms with the help of the most trusted course: DSA Self Paced. Become industry ready at a student-friendly price.
- Killing threads in Java
- Joining Threads in Java
- Output of Java program | Set 16 (Threads)
- Introducing Threads in Socket Programming in Java
- Producer-Consumer solution using threads in Java
- Understanding threads on Producer Consumer Problem | Java
- Green vs Native Threads and Deprecated Methods in Java
- Print 1 2 3 infinitely using threads in C
- Two way communication between Client and Server using Win32 Threads
- Maximum number of threads that can be created within a process in C
- Daemon thread in Java
- Difference between Single User and Multi User Database Systems
- Difference between Process and User Level Thread
- How to read a Matrix from user in Java?
- User-defined Custom Exception in Java
- Swap two Strings without using third user defined variable in Java
- Using TreeMap to sort User-defined Objects in Java
- How to create a Java HashMap of user defined class type?
- Difference between user defined function and library function in C/C++
- Difference between User Level thread and Kernel Level thread
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to firstname.lastname@example.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.