Preliminary test fails! Threads problem

[Miguel Roque]

Hello.
I'me starting to make some tests so that I can test the server and the reservation mechanism. I have the lock manager as follows:

  
     synchronized public void lock(int recNum, Object clientId) {
        Integer recordNumber = new Integer(recNum);
        if ( recNum == DATABASE_LOCK ) {
            while (!mapLocks.isEmpty()) {
                try {
                    wait();
                } catch (InterruptedException e) {
                    break;
                }
            }
        } else {
            while (mapLocks.containsKey(recordNumber) || mapLocks.containsKey(ALL_DATABASE_LOCKED) ) {
                try {
                    wait();
                } catch (InterruptedException e) {
                    break;
                }
            }
        }
        mapLocks.put(recordNumber, clientId);
    }
    synchronized public void unlock(int recNum, Object clientID) {
        Integer recordNumber = new Integer(recNum);
        if (mapLocks.get(recordNumber).equals(clientID)) {
            mapLocks.remove(recordNumber);
            notifyAll();
        }
    }

As i've used a factory, i get a diferent client number, so here i don't have any problem
The main problem for now is that i've build a small test program that makes seat reservation in one flight. The program is as follows:

  
...
public static void main(String[] args) {
        FBNServerTest test1 = new FBNServerTest();
        test1.setName("Client1");
        FBNServerTest test2 = new FBNServerTest();
        test2.setName("Client2");
        FBNServerTest test3 = new FBNServerTest();
        test3.setName("Client3");
        FBNServerTest test4 = new FBNServerTest();
        test4.setName("Client4");
        FBNServerTest test5 = new FBNServerTest();
        test5.setName("Client5");
        
        test1.start();
        test2.start();
        test3.start();
        test4.start();
        test5.start();
        
        while (   test1.isAlive() 
                || test2.isAlive() 
                || test3.isAlive()
                || test4.isAlive() 
                || test5.isAlive() ) {
        }
        System.out.println("Completed all tests.");
        
}
...

And the code to make the seat reservation:

  
        try {
            df = db.find(this.flightNumber);
            if (df!=null) {
                tempDataFieldValues = df.getValues();
                recordToChange = df.getRecordNumber();
                tmpFields = df.getFields();
                db.lock(recordToChange);
                asAnyRecordBeenLocked = true;
                availableSeats = Integer.parseInt(tempDataFieldValues[FBNFieldConstants.AVAILABLE_SEATS].trim());
                if (availableSeats >= seatsToReserve) {
                    availableSeats -= seatsToReserve;
                    tempDataFieldValues[FBNFieldConstants.AVAILABLE_SEATS] = Integer.toString(availableSeats);
                    df = new DataInfo(recordToChange,tmpFields,tempDataFieldValues);
                    db.modify(df);
                    // Let's force the server to retain a
                    // record locked for a big amount of time!
                    Thread t = Thread.currentThread();
                    try {
                        t.sleep(10000); // Put here a bigger value!
                    } catch (InterruptedException exp) {
                    }
                } else {
                    if (availableSeats==0) {
                        throw new NoSeatsAvailableException("There are no seats available for this flight.");
                    } else {
                        throw new NotEnoughSeatsAvailableException("Not enough seats available for this flight.");
                    }
                }
            } else {
                throw new DatabaseException("Unable to find the selected flight in the database.");
            }
        } catch (DatabaseException e) {
            throw e; //DatabaseException();
        } catch (RemoteException e) {
            throw e;
        } finally {
            try {
                if (asAnyRecordBeenLocked) { db.unlock(df.getRecordNumber()); }
            } catch (DatabaseException e) {
                throw e;
            } catch (RemoteException e) {
                throw e;
            }
        }

The big problem is when i run the test program with this 5 clients, it only reserves 2 seats
After the lock and unlock method in the server i've put a print to show the result, and the problem cames here. The output in the server is as follows:

  
client4 locked
client4 unlocked
client3 locked
client2 locked
client3 unlocked
client2 unlocked
client5 locked
client1 locked
client5 unlocked
client1 unlocked

I'm with all this. Where is the problem?
Thanks for your help.
Miguel

[Mark Spritzler]

First is a little thing. You do not need the break; lines in the LockManager.
Second, it appears that there are no exceptions being thrown, else you would have ahd a stack trace. So that means you need to debug your booking method, as you don't show your test thread code.
The way I like to debug is longer winded than some tools that are out there, but I use the old "System.out.println("I am here in the code");"
Then you can see how far the code gets. If you are using 1.4 then you can add assertions to your code to make sure that the data/variables are set to where you would expect them to be.
Sorry I couldn't be of more help to you, but sometimes debugging is the best learning tool, and I wouldn't want to lose that great tool.
Mark

[Miguel Roque]

Hello.
Just seen the error ! I was using the data from the find method to make the reservation .
I was not following the Lock->Read->Modify->Unlock .
By the way. I like to use the tipical debug System.out.println("Here I am"); i'ts the best debug tool that I know .
Thanks for the help.
Miguel