testing locks.

[Prakash Krishnamurthy]

I am trying to test my locks. I have a test class that spawns a few threads. Each thread represents a client which is booking the same flight. The intention is to have multiple clients book the same flight at the same time so that I know if my locking and unlocking algorithm is working or not.

The problem is, on the client side I have the thread name with the output, so I know which client is doing what. But on the server side, I am not able to associate the clients with their respective threads on the server.
Any ideas how I can go about this?

[Andrew Monkhouse]

Hi Prakash,
Depending on how readable you want your output to be, you have some choices:
Within the thread, if you simply do a System.out.print(this) you should get at least some sort of unique identifier (possibly the hashcode for the thread), and possibly a whole lot of debugging information as well.

public class ThreadTest extends Thread {
    public static void main(String[] args) {
        new ThreadTest().start();
        new ThreadTest().start();
    }
    public void run() {
        System.out.println("Thread: " + this);
    }
}
Thread: Thread[Thread-1,5,main]
Thread: Thread[Thread-2,5,main]

Or, overide the constructor (you are doing that anyway for your tests), and pass in a unique identifier:

public class ThreadTest extends Thread {
    int id;
    public static void main(String[] args) {
        for (int i = 0; i < 2; i++) {
            new ThreadTest(i).start();
        }
    }
    public ThreadTest(int id) {
        this.id = id;
    }
    public void run() {
        System.out.println(id + " Thread: " + this);
    }
}
0 Thread: Thread[Thread-1,5,main]
1 Thread: Thread[Thread-2,5,main]

You can even override the toString() method to make it nicer:

public class ThreadTest extends Thread {
    int id;
    public static void main(String[] args) {
        for (int i = 0; i < 2; i++) {
            new ThreadTest(i).start();
        }
    }
    public ThreadTest(int id) {
        this.id = id;
    }
    public void run() {
        System.out.println(this);
    }
    public String toString() {
        return "Currently running thread " + id;
    }
}
Currently running thread 0
Currently running thread 1

Does any of this help? If not please give more details of what you are trying to do.
Regards, Andrew

[Prakash Krishnamurthy]

Andrew:
Probably, I wasn't too clear about my question. Let me re-ask this question. On the clientside when i run my threadtest class to test my locks I get the following output

 Thread Name: Thread[One,5,main]
Thread Name: Thread[Two,5,main]
One: getting into criteriaFind
Two: getting into criteriaFind
Two: going to book record number 1
Two:getting into locking
Two :Finished Locking
One: going to book record number 1
One:getting into locking
One :Finished Locking
Two: Finished modifying the database!
One: Finished modifying the database!
Two: finished unlocking record no 1
One: finished unlocking record no 1
 

On the server though, I get this

  
The record number that is about to be locked is 1
 Locking record number 1
ReadWriteLock: method writelock
There seems to be no outstanding locks, hence locking the current thread
hashed record numebr 1
The record number that is about to be locked is 1
Somebody is accessing this record, Please wait!
Just about to enter the unlock for record no 1
Entered done method
done method is finished
Just about to enter the unlock for record no 1
Entered done method
done method is finished

On the client I am clear about the thread name. But, on the server I am not sure which thread is locking and which thread is unlocking. Like, on the server side it says .
"The record number that is about to be locked is 1
Somebody is accessing this record, Please wait!
Just about to enter the unlock for record no 1"
It is not clear to me which thread does this corrrespond to...
I am going to try just doing

 System.out.println("Thread : "+ this); 

and see if things are clear on the server side. I think my question did get answered, though. I was just trying to make sure I had explained the problem well.:-)
[ April 16, 2003: Message edited by: Prakash Krishnamurthy ]