Daemon Thread

title: Daemon Thread in Java description: Daemon threads kya hain aur kab use karte hain

Background service threads jo main thread ke khatam hone par automatically khatam ho jaate hain.

Create karna

java exampleWoHoTech

Thread t = new Thread(() -> {
    while (true) {
        System.out.println("Daemon running...");
        try { Thread.sleep(500); }
        catch (InterruptedException e) { break; }
    }
});

t.setDaemon(true); // start() se pehle set karo!
t.start();

Thread.sleep(2000);
System.out.println("Main thread khatam");
// Daemon thread bhi band ho jayega

Daemon vs User Thread

	Daemon Thread	User Thread
--	--	--
Purpose	Background service	Main logic
JVM shutdown	JVM daemon wait nahi karta	JVM wait karta hai
Example	Garbage Collector, JIT Compiler	main(), worker threads
setDaemon()	`true`	`false` (default)

Check karna

java exampleWoHoTech

Thread t = new Thread(() -> { });
System.out.println(t.isDaemon()); // false (default)
t.setDaemon(true);
System.out.println(t.isDaemon()); // true

Use Cases

Log monitoring
Garbage collection
Auto-save feature
Heartbeat / health check
Cache cleanup

Important Rule

java exampleWoHoTech

t.setDaemon(true);
t.start();
// t.setDaemon(true); // Error! start() ke baad set nahi kar sakte
// IllegalThreadStateException

title: Daemon Thread in Java description: Daemon threads kya hain aur kab use karte hain

Background service threads jo main thread ke khatam hone par automatically khatam ho jaate hain.

Create karna

java exampleWoHoTech

Thread t = new Thread(() -> {
    while (true) {
        System.out.println("Daemon running...");
        try { Thread.sleep(500); }
        catch (InterruptedException e) { break; }
    }
});

t.setDaemon(true); // start() se pehle set karo!
t.start();

Thread.sleep(2000);
System.out.println("Main thread khatam");
// Daemon thread bhi band ho jayega

Daemon vs User Thread

	Daemon Thread	User Thread
--	--	--
Purpose	Background service	Main logic
JVM shutdown	JVM daemon wait nahi karta	JVM wait karta hai
Example	Garbage Collector, JIT Compiler	main(), worker threads
setDaemon()	`true`	`false` (default)

Check karna

java exampleWoHoTech

Thread t = new Thread(() -> { });
System.out.println(t.isDaemon()); // false (default)
t.setDaemon(true);
System.out.println(t.isDaemon()); // true

Use Cases

Log monitoring
Garbage collection
Auto-save feature
Heartbeat / health check
Cache cleanup

Important Rule

java exampleWoHoTech

t.setDaemon(true);
t.start();
// t.setDaemon(true); // Error! start() ke baad set nahi kar sakte
// IllegalThreadStateException

Daemon Thread

Create karna

Daemon vs User Thread

Check karna

Use Cases

Important Rule

Continue learning this concept

Daemon Thread

Create karna

Daemon vs User Thread

Check karna

Use Cases

Important Rule

Continue learning this concept