public void init(Configuration conf) {
    LOG.info("QueryMaster init");
    try {
      this.systemConf = (TajoConf) conf;
      this.connPool = RpcConnectionPool.getPool(systemConf);

      querySessionTimeout = systemConf.getIntVar(TajoConf.ConfVars.QUERY_SESSION_TIMEOUT);
      queryMasterContext = new QueryMasterContext(systemConf);

      clock = new SystemClock();

      this.dispatcher = new TajoAsyncDispatcher("querymaster_" + System.currentTimeMillis());
      addIfService(dispatcher);

      this.storageManager = StorageManagerFactory.getStorageManager(systemConf);

      globalPlanner = new GlobalPlanner(systemConf, workerContext);

      dispatcher.register(QueryStartEvent.EventType.class, new QueryStartEventHandler());

    } catch (Throwable t) {
      LOG.error(t.getMessage(), t);
      throw new RuntimeException(t);
    }
    super.init(conf);
  }
    @Override
    public void run() {
      LOG.info("Start TajoWorkerAllocationThread");
      CallFuture<TajoMasterProtocol.WorkerResourceAllocationResponse> callBack =
          new CallFuture<TajoMasterProtocol.WorkerResourceAllocationResponse>();

      int requiredMemoryMBSlot = 512; // TODO
      int requiredDiskSlots = 1; // TODO
      TajoMasterProtocol.WorkerResourceAllocationRequest request =
          TajoMasterProtocol.WorkerResourceAllocationRequest.newBuilder()
              .setMemoryMBSlots(requiredMemoryMBSlot)
              .setDiskSlots(requiredDiskSlots)
              .setNumWorks(event.getRequiredNum())
              .setExecutionBlockId(event.getExecutionBlockId().getProto())
              .build();

      RpcConnectionPool connPool = RpcConnectionPool.getPool(queryTaskContext.getConf());
      NettyClientBase tmClient = null;
      try {
        tmClient =
            connPool.getConnection(
                queryTaskContext.getQueryMasterContext().getWorkerContext().getTajoMasterAddress(),
                TajoMasterProtocol.class,
                true);
        TajoMasterProtocol.TajoMasterProtocolService masterClientService = tmClient.getStub();
        masterClientService.allocateWorkerResources(null, request, callBack);
      } catch (Exception e) {
        connPool.closeConnection(tmClient);
        tmClient = null;
        LOG.error(e.getMessage(), e);
      } finally {
        connPool.releaseConnection(tmClient);
      }

      TajoMasterProtocol.WorkerResourceAllocationResponse response = null;
      while (!stopped.get()) {
        try {
          response = callBack.get(3, TimeUnit.SECONDS);
          break;
        } catch (InterruptedException e) {
          if (stopped.get()) {
            return;
          }
        } catch (TimeoutException e) {
          LOG.info("No available worker resource for " + event.getExecutionBlockId());
          continue;
        }
      }
      int numAllocatedWorkers = 0;

      if (response != null) {
        List<TajoMasterProtocol.WorkerAllocatedResource> workerHosts =
            response.getWorkerAllocatedResourceList();
        ExecutionBlockId executionBlockId = event.getExecutionBlockId();

        List<Container> containers = new ArrayList<Container>();
        for (TajoMasterProtocol.WorkerAllocatedResource eachWorker : workerHosts) {
          TajoWorkerContainer container = new TajoWorkerContainer();
          NodeIdPBImpl nodeId = new NodeIdPBImpl();

          nodeId.setHost(eachWorker.getWorkerHost());
          nodeId.setPort(eachWorker.getPeerRpcPort());

          TajoWorkerContainerId containerId = new TajoWorkerContainerId();

          containerId.setApplicationAttemptId(
              ApplicationIdUtils.createApplicationAttemptId(executionBlockId.getQueryId()));
          containerId.setId(containerIdSeq.incrementAndGet());

          container.setId(containerId);
          container.setNodeId(nodeId);

          WorkerResource workerResource = new WorkerResource();
          workerResource.setAllocatedHost(nodeId.getHost());
          workerResource.setPeerRpcPort(nodeId.getPort());
          workerResource.setQueryMasterPort(eachWorker.getQueryMasterPort());
          workerResource.setPullServerPort(eachWorker.getWorkerPullServerPort());
          workerResource.setMemoryMBSlots(requiredMemoryMBSlot);
          workerResource.setDiskSlots(requiredDiskSlots);

          container.setWorkerResource(workerResource);

          containers.add(container);
        }

        SubQueryState state = queryTaskContext.getSubQuery(executionBlockId).getState();
        if (!SubQuery.isRunningState(state)) {
          List<WorkerResource> workerResources = new ArrayList<WorkerResource>();
          for (Container eachContainer : containers) {
            workerResources.add(((TajoWorkerContainer) eachContainer).getWorkerResource());
          }
          try {
            TajoContainerProxy.releaseWorkerResource(
                queryTaskContext, executionBlockId, workerResources);
          } catch (Exception e) {
            LOG.error(e.getMessage(), e);
          }
          return;
        }

        if (workerHosts.size() > 0) {
          if (LOG.isDebugEnabled()) {
            LOG.debug("SubQueryContainerAllocationEvent fire:" + executionBlockId);
          }
          queryTaskContext
              .getEventHandler()
              .handle(new SubQueryContainerAllocationEvent(executionBlockId, containers));
        }
        numAllocatedWorkers += workerHosts.size();
      }
      if (event.getRequiredNum() > numAllocatedWorkers) {
        ContainerAllocationEvent shortRequestEvent =
            new ContainerAllocationEvent(
                event.getType(),
                event.getExecutionBlockId(),
                event.getPriority(),
                event.getResource(),
                event.getRequiredNum() - numAllocatedWorkers,
                event.isLeafQuery(),
                event.getProgress());
        queryTaskContext.getEventHandler().handle(shortRequestEvent);
      }
      LOG.info("Stop TajoWorkerAllocationThread");
    }