/**
     * Test case for
     * <a href="https://issues.apache.org/jira/browse/JCR-2908">JCR-2908</a>.
     */
    public void testAddNodeInMultipleThreads() throws Exception {
        Session session = getHelper().getSuperuserSession();
        // make sure that 'testNode' does not exist at the beginning
        // of the test
        while (session.nodeExists("/testNode")) {
            session.getNode("/testNode").remove();
            session.save();
        }

        // create 'testNode' that has two child
        Node node = session.getRootNode().addNode("testNode");
        Node child1 = node.addNode("child1");
        String child1Path = child1.getPath();
        Node child2 = node.addNode("child2");
        String child2Path = child2.getPath();
        session.save();
        session.logout();
        
        //create versionable nodes under child1 and child2
        //repeat several times
        for(int i=0; i<5; ++i){
            CountDownLatch startSignal = new CountDownLatch(1);
            CountDownLatch endSignal = new CountDownLatch(2);
            AddNodeThread t1 = new AddNodeThread(child1Path, 20, startSignal, endSignal);
            t1.start();
            AddNodeThread t2 = new AddNodeThread(child2Path, 20, startSignal, endSignal);
            t2.start();
            
            startSignal.countDown();
            endSignal.await();
            
            assertTrue(t1.isSuccess());
            assertTrue(t2.isSuccess());
        }
    }
    
    class AddNodeThread extends Thread {
        private String parentPath;
        private int childCount=0;
        private boolean success = false;
        private CountDownLatch startSignal;
        private CountDownLatch endSignal; 

        AddNodeThread(String parentPath, int childCount, CountDownLatch startSignal, CountDownLatch endSignal) {
            this.parentPath = parentPath;
            this.childCount = childCount;
            this.startSignal = startSignal;
            this.endSignal = endSignal;
        }

        public void run() {
            Session session = null;
            try {
                startSignal.await();
                session = getHelper().getSuperuserSession();
                UserTransaction utx = new UserTransactionImpl(session);
                utx.begin();
                Node parent = session.getNode(parentPath);
                for(int i=0; i<childCount; ++i){
                    Node child = parent.addNode("child" + i);
                    child.addMixin(NodeType.MIX_VERSIONABLE);
                    session.save();
                    child.checkin();
                }
                session.save();
                utx.commit();
                success = true;
            } catch (Exception e) {
                e.printStackTrace();
                fail("unexpected exception");
            }finally{
                session.logout();
                endSignal.countDown();
            }
        }
        
        public boolean isSuccess(){
            return success;
        }
    }