Program: 106916
Project: 106916
Buggy source:
@DB protected boolean startRebalance(final long hostId){
  HostVO host=_hostDao.findById(hostId);
  if (host == null || host.getRemoved() != null) {
    s_logger.warn("String_Node_Str");
    return false;
  }
synchronized (_agents) {
    ClusteredDirectAgentAttache attache=(ClusteredDirectAgentAttache)_agents.get(hostId);
    if (attache != null && attache.getQueueSize() == 0 && attache.getNonRecurringListenersSize() == 0) {
      _agentToTransferIds.remove(hostId);
      removeAgent(attache,Status.Rebalancing);
      ClusteredAgentAttache forwardAttache=(ClusteredAgentAttache)createAttache(hostId);
      if (forwardAttache == null) {
        s_logger.warn("String_Node_Str" + hostId + "String_Node_Str");
        return false;
      }
      s_logger.debug("String_Node_Str" + hostId + "String_Node_Str");
      forwardAttache.setTransferMode(true);
      _agents.put(hostId,forwardAttache);
    }
 else {
      if (attache == null) {
        s_logger.warn("String_Node_Str" + hostId + "String_Node_Str"+ _nodeId+ "String_Node_Str");
      }
 else {
        s_logger.warn("String_Node_Str" + hostId + "String_Node_Str"+ attache.getQueueSize()+ "String_Node_Str"+ attache.getNonRecurringListenersSize()+ "String_Node_Str");
      }
      return false;
    }
  }
  Transaction txn=Transaction.currentTxn();
  txn.start();
  s_logger.debug("String_Node_Str" + hostId + "String_Node_Str"+ Status.Rebalancing);
  host.setManagementServerId(null);
  _hostDao.updateStatus(host,Event.StartAgentRebalance,_nodeId);
  _hostTransferDao.startAgentTransfer(hostId);
  txn.commit();
  return true;
}

Fixed version (ground truth):
@DB protected boolean startRebalance(final long hostId){
  HostVO host=_hostDao.findById(hostId);
  if (host == null || host.getRemoved() != null) {
    s_logger.warn("String_Node_Str");
    return false;
  }
synchronized (_agents) {
    ClusteredDirectAgentAttache attache=(ClusteredDirectAgentAttache)_agents.get(hostId);
    if (attache != null && attache.getQueueSize() == 0 && attache.getNonRecurringListenersSize() == 0) {
      removeAgent(attache,Status.Rebalancing);
      ClusteredAgentAttache forwardAttache=(ClusteredAgentAttache)createAttache(hostId);
      if (forwardAttache == null) {
        s_logger.warn("String_Node_Str" + hostId + "String_Node_Str");
        return false;
      }
      s_logger.debug("String_Node_Str" + hostId + "String_Node_Str");
      forwardAttache.setTransferMode(true);
      _agents.put(hostId,forwardAttache);
    }
 else {
      if (attache == null) {
        s_logger.warn("String_Node_Str" + hostId + "String_Node_Str"+ _nodeId+ "String_Node_Str");
      }
 else {
        s_logger.warn("String_Node_Str" + hostId + "String_Node_Str"+ attache.getQueueSize()+ "String_Node_Str"+ attache.getNonRecurringListenersSize()+ "String_Node_Str");
      }
      return false;
    }
  }
  Transaction txn=Transaction.currentTxn();
  txn.start();
  s_logger.debug("String_Node_Str" + hostId + "String_Node_Str"+ Status.Rebalancing);
  host.setManagementServerId(null);
  _hostDao.updateStatus(host,Event.StartAgentRebalance,_nodeId);
  _hostTransferDao.startAgentTransfer(hostId);
  txn.commit();
  return true;
}