Synchronization of shared object by TimerTask

Hi All

Thanks in advance

I have TimerTask to execute at every say 10 sec.
Task might take more than 10 sec...say 20 sec.
So another call for run is fired before previous call has returned.
Both call to run method try to access the setData method
and are successfull in accessing setData even though it is synchronized
method.

Problem:
========
I expected it to synchronized but it is not..
Can Any One Suggest Why? Solution

Strange Behaviour:
And tried it Eclipse with Tomcat and found this problem.
However when i exeucted it as java application I found that run method
itself is called one after another.
No need of synchronization. However in Servlet it is not so.

Sample Code:
==========

Class MyTimerTask extends TimerTask
{
    MyData data;
    MyDB db;
    public synchronized void setData( )
    {
        int x = db.getNum();
        Thread.sleep(20000);//forced to sleep for 20 sec, simulate
multi thread access
        data.n=x;
    }

    public run()
    {
                setData( );
    }
}

class myServlet
{
   init()
   {
         MyTimerTask myTask = new MyTimerTask();
         Timer myTimer = new Timer(true);
         myTimer.schedule(myTask,10000,10000);
    }
}