When does java thread cache refresh happens?

Question

Thread 1: is executing this loop

while(running) {
// Do Task()
} 
println(\"Done\");

Thread 2 sets running false In case running is a vol

Answer 1

Why not try it yourself?

public class ThreadTest {

private static boolean running = true;

public static void main(String[] args) throws InterruptedException {
    Thread t = new Thread() {
        public void run() {
            while( running ) {
                System.out.println( "Running.");
            }
            long l = System.nanoTime();
            System.out.println( "Stopped at "+l);

        }
    };
    t.start();
    Thread.sleep( 1 );
    running = false;
    long l = System.nanoTime();
    System.out.println( "Stopping at "+l);
}
}

It's by no means a perfect test but it gives you a rough estimate. On my machine the difference was approx 25ms. Of course it has to execute the System.out.println too, but that certainly doesn't take that long.