Thread.sleep() does not release lock?

[Chandra Bhatt]

package threads;
 
public class DemoThread extends Thread {
 
    /** Creates a new instance of DemoThread */
    public DemoThread() {
    }
 
    public void run() {
        int i=0;
        synchronized(this) {
            while(++i<=50) {
                sum=i;
                try{
                    sleep(100);
                    System.out.println("Woke up from sleep");
                    if(i>=5) this.notify();
                }catch(InterruptedException ie) {
                    ie.printStackTrace();
                    System.exit(1);
                }
            }
        }
    }
private static int sum;    
 
    public static void main(String... args) {
        
        DemoThread dt = new DemoThread();
        dt.start();
 
        synchronized(dt) {
            try{
                dt.wait();
                System.out.println("sum = " + sum);
            }catch(InterruptedException ie){
                ie.printStackTrace();
                System.exit(1);
            }
        }        
    }
}

Output:

Woke up from sleep
Woke up from sleep
Woke up from sleep
Woke up from sleep
Woke up from sleep
Woke up from sleep
Woke up from sleep
Woke up from sleep
Woke up from sleep
Woke up from sleep
sum = 50

Does this example demonstrate the fact "Thread.sleep(...) does not release the lock"?


Kindly suggest!



Thanks,
cmbhatt
[ April 24, 2007: Message edited by: Chandra Bhatt ]

[Henry Wong]

Does this example demonstrate the fact "Thread.sleep(...) does not release the lock"?

The Thread.sleep() method does not release any locks. Where did you read/heard that it did?

Henry

[Chandra Bhatt]

Thanks Henry,

The Thread.sleep() method does not release any locks. Where did you read/heard that it did?

Nay, I only read/heard the original one "does not release...".

Actually I supposed to see what exactly happens in case if
an object is notified from within a loop where we call to the
sleep(...) method inside the sync block.


Anyways thank for your reply!


Regards,
cmbhatt

[swarna dasa]

I don't get this

I thought the output would be 50.
Though the demothread calls notify it doesn't leave the synchronized context till i=50, so the main thread cannot print the sum, as it occurs in the synchronized context.

What am i failing to understand?

[marc weber]

Originally posted by swarna dasa:
... I thought the output would be 50...

As posted, the output should be 50. I'm guessing this code was altered to get more "manageable" output.

...while(++i<=10)...