Daemon thread question

[Yan Bai]

For non-daemon thread, the program, say - the thread runs main(), will not terminate until all threads complete. But for daemon, since it is supposed to run in the background of one program, the program can terminate once the main() finishes its job, even those daemon threads are still active.
My question is,
Assume a daemon thread has an infinite loop, will it continue running after the main() finished? So it *seems* that the program is finished, but indeed, it's not really done yet. One needs to kill the process manually sometime later when he noticed this, is this a potential hole?
What are daemon threads use for then? :roll:
Thanks very much
-Yan

[Barry Gaunt]

Maybe this will help:
Beware the Daemons
-Barry

[Anthony Villanueva]

Originally posted by Yan Bai:
Assume a daemon thread has an infinite loop, will it continue running after the main() finished?

public class Test16
{   
public static void main (String[] args)
{
Thread t = new Thread(new Runner());
t.setDaemon(true);
t.start();
for(int i=0;i<1000; i++);
}
}    
class Runner implements Runnable
{
public void run()
{
for(; :wink:  System.out.println("running...");
}
}

It wouldn't.

[Barry Gaunt]

Tony means

for(;; )   System.out.println("running..."); //  :wink: 

[Yan Bai]

Thanks for the help!
Just want to confirm - Does this mean that both user threads and daemon threads will terminate once the main program terminates?

[Paul Villangca]

Hi Yan Bai,
There's nothing special about the 'main program' thread, it's just another user thread. That being said, the Java runtime terminates only if there are no more user threads running, the main() method among them.
Hope this helps,
Paul Villangca

[Anthony Villanueva]

Beware the Graemlins too!