TestKillQuery::testKillQueryFromInitState causes NPE

2015-11-02 21:13:16,126 INFO: org.apache.tajo.querymaster.Query (handle(868)) - Processing q_1446498795879_0000 of type START
2015-11-02 21:13:16,128 INFO: org.apache.tajo.engine.planner.global.ParallelExecutionQueue (first(84)) - Initial executable blocks [eb_1446498795879_0000_000003]
2015-11-02 21:13:16,129 INFO: org.apache.tajo.querymaster.Query (handle(886)) - q_1446498795879_0000 Query Transitioned from QUERY_NEW to QUERY_RUNNING
2015-11-02 21:13:16,129 INFO: org.apache.tajo.querymaster.Stage (calculateShuffleOutputNum(1026)) - ============>>>>> Unexpected Case! <<<<<================
2015-11-02 21:13:16,129 INFO: org.apache.tajo.querymaster.Stage (calculateShuffleOutputNum(1030)) - eb_1446498795879_0000_000003, Table's volume is approximately 1 MB
2015-11-02 21:13:16,129 INFO: org.apache.tajo.querymaster.Stage (calculateShuffleOutputNum(1033)) - eb_1446498795879_0000_000003, The determined number of partitions is 1
2015-11-02 21:13:16,150 INFO: org.apache.tajo.querymaster.Stage (initTaskScheduler(901)) - org.apache.tajo.querymaster.DefaultTaskScheduler is chosen for the task scheduling for eb_1446498795879_0000_000003
2015-11-02 21:13:16,151 INFO: org.apache.tajo.storage.FileTablespace (getSplits(564)) - Total # of splits: 1
2015-11-02 21:13:16,152 INFO: org.apache.tajo.storage.FileTablespace (getSplits(564)) - Total # of splits: 1
2015-11-02 21:13:16,152 INFO: org.apache.tajo.querymaster.Repartitioner (scheduleFragmentsForJoinQuery(230)) - [Distributed Join Strategy] : Broadcast Join, base_table=default.t2, base_volume=724
2015-11-02 21:13:16,152 INFO: org.apache.tajo.storage.FileTablespace (getSplits(564)) - Total # of splits: 1
2015-11-02 21:13:16,153 INFO: org.apache.tajo.querymaster.Query (handle(868)) - Processing q_1446498795879_0000 of type KILL
2015-11-02 21:13:16,153 INFO: org.apache.tajo.querymaster.Query (handle(886)) - q_1446498795879_0000 Query Transitioned from QUERY_RUNNING to QUERY_KILL_WAIT
2015-11-02 21:13:16,153 INFO: org.apache.tajo.storage.FileTablespace (getSplits(564)) - Total # of splits: 1
2015-11-02 21:13:16,153 INFO: org.apache.tajo.querymaster.DefaultTaskScheduler (stop(163)) - Task Scheduler stopped
2015-11-02 21:13:16,153 INFO: org.apache.tajo.querymaster.Stage (run(853)) - 1 objects are scheduled
2015-11-02 21:13:16,155 FATAL: org.apache.hadoop.yarn.event.AsyncDispatcher (dispatch(181)) - Error in dispatcher thread
java.lang.NullPointerException
	at org.apache.tajo.querymaster.DefaultTaskScheduler.releaseTaskAttempt(DefaultTaskScheduler.java:332)
	at org.apache.tajo.querymaster.Stage$TaskCompletedTransition.transition(Stage.java:1228)
	at org.apache.tajo.querymaster.Stage$TaskCompletedTransition.transition(Stage.java:1212)
	at org.apache.hadoop.yarn.state.StateMachineFactory$SingleInternalArc.doTransition(StateMachineFactory.java:362)
	at org.apache.hadoop.yarn.state.StateMachineFactory.doTransition(StateMachineFactory.java:302)
	at org.apache.hadoop.yarn.state.StateMachineFactory.access$300(StateMachineFactory.java:46)
	at org.apache.hadoop.yarn.state.StateMachineFactory$InternalStateMachine.doTransition(StateMachineFactory.java:448)
	at org.apache.tajo.querymaster.Stage.handle(Stage.java:801)
	at org.apache.tajo.querymaster.QueryMasterTask$StageEventDispatcher.handle(QueryMasterTask.java:213)
	at org.apache.tajo.querymaster.QueryMasterTask$StageEventDispatcher.handle(QueryMasterTask.java:207)
	at org.apache.hadoop.yarn.event.AsyncDispatcher.dispatch(AsyncDispatcher.java:175)
	at org.apache.tajo.querymaster.TestKillQuery$MockAsyncDispatch.dispatch(TestKillQuery.java:305)
	at org.apache.hadoop.yarn.event.AsyncDispatcher$1.run(AsyncDispatcher.java:108)
	at java.lang.Thread.run(Thread.java:745)
2015-11-02 21:13:16,156 INFO: org.apache.tajo.querymaster.Stage (transition(1407)) - Stage completed - eb_1446498795879_0000_000003 (total=1, success=0, killed=0)
2015-11-02 21:13:16,157 ERROR: org.apache.tajo.querymaster.Stage (transition(1430)) - 
java.lang.NullPointerException
	at org.apache.tajo.querymaster.Stage.computeStatFromTasks(Stage.java:697)
	at org.apache.tajo.querymaster.Stage.finalizeStats(Stage.java:771)
	at org.apache.tajo.querymaster.Stage.complete(Stage.java:532)
	at org.apache.tajo.querymaster.Stage$StageCompleteTransition.transition(Stage.java:1426)
	at org.apache.tajo.querymaster.Stage$StageCompleteTransition.transition(Stage.java:1399)
	at org.apache.hadoop.yarn.state.StateMachineFactory$MultipleInternalArc.doTransition(StateMachineFactory.java:385)
	at org.apache.hadoop.yarn.state.StateMachineFactory.doTransition(StateMachineFactory.java:302)
	at org.apache.hadoop.yarn.state.StateMachineFactory.access$300(StateMachineFactory.java:46)
	at org.apache.hadoop.yarn.state.StateMachineFactory$InternalStateMachine.doTransition(StateMachineFactory.java:448)
	at org.apache.tajo.querymaster.Stage.handle(Stage.java:801)
	at org.apache.tajo.querymaster.QueryMasterTask$StageEventDispatcher.handle(QueryMasterTask.java:213)
	at org.apache.tajo.querymaster.QueryMasterTask$StageEventDispatcher.handle(QueryMasterTask.java:207)
	at org.apache.hadoop.yarn.event.AsyncDispatcher.dispatch(AsyncDispatcher.java:175)
	at org.apache.tajo.querymaster.TestKillQuery$MockAsyncDispatch.dispatch(TestKillQuery.java:305)
	at org.apache.hadoop.yarn.event.AsyncDispatcher$1.run(AsyncDispatcher.java:108)
	at java.lang.Thread.run(Thread.java:745)
2015-11-02 21:13:16,157 INFO: org.apache.tajo.querymaster.DefaultTaskScheduler (stop(163)) - Task Scheduler stopped
2015-11-02 21:13:16,158 ERROR: org.apache.tajo.querymaster.Stage (handle(804)) - Can't handle this event at current state, eventType:SQ_STAGE_COMPLETED, oldState:KILL_WAIT, nextState:KILL_WAIT
org.apache.hadoop.yarn.state.InvalidStateTransitonException: Invalid event: SQ_STAGE_COMPLETED at KILL_WAIT
	at org.apache.hadoop.yarn.state.StateMachineFactory$MultipleInternalArc.doTransition(StateMachineFactory.java:388)
	at org.apache.hadoop.yarn.state.StateMachineFactory.doTransition(StateMachineFactory.java:302)
	at org.apache.hadoop.yarn.state.StateMachineFactory.access$300(StateMachineFactory.java:46)
	at org.apache.hadoop.yarn.state.StateMachineFactory$InternalStateMachine.doTransition(StateMachineFactory.java:448)
	at org.apache.tajo.querymaster.Stage.handle(Stage.java:801)
	at org.apache.tajo.querymaster.QueryMasterTask$StageEventDispatcher.handle(QueryMasterTask.java:213)
	at org.apache.tajo.querymaster.QueryMasterTask$StageEventDispatcher.handle(QueryMasterTask.java:207)
	at org.apache.hadoop.yarn.event.AsyncDispatcher.dispatch(AsyncDispatcher.java:175)
	at org.apache.tajo.querymaster.TestKillQuery$MockAsyncDispatch.dispatch(TestKillQuery.java:305)
	at org.apache.hadoop.yarn.event.AsyncDispatcher$1.run(AsyncDispatcher.java:108)
	at java.lang.Thread.run(Thread.java:745)
2015-11-02 21:13:16,158 INFO: org.apache.tajo.querymaster.Query (handle(868)) - Processing q_1446498795879_0000 of type STAGE_COMPLETED
2015-11-02 21:13:16,158 INFO: org.apache.tajo.querymaster.Query (transition(815)) - Complete Stage[eb_1446498795879_0000_000003], State: ERROR, 1/1. 
2015-11-02 21:13:16,158 INFO: org.apache.tajo.querymaster.DefaultTaskScheduler (stop(163)) - Task Scheduler stopped
2015-11-02 21:13:16,158 INFO: org.apache.tajo.querymaster.Query (handle(868)) - Processing q_1446498795879_0000 of type QUERY_COMPLETED
2015-11-02 21:13:16,158 INFO: org.apache.tajo.querymaster.Query (handle(886)) - q_1446498795879_0000 Query Transitioned from QUERY_KILL_WAIT to QUERY_ERROR
2015-11-02 21:13:16,159 INFO: org.apache.tajo.querymaster.Query (handle(868)) - Processing q_1446498795879_0000 of type STAGE_COMPLETED
2015-11-02 21:13:16,159 INFO: org.apache.tajo.querymaster.QueryMasterTask (handle(296)) - Query completion notified from q_1446498795879_0000 final state: QUERY_ERROR
2015-11-02 21:13:16,159 WARN: org.apache.tajo.querymaster.QueryMaster (stopQuery(283)) - No query info:q_1446498795879_0000
java.io.IOException: QUERY_ERROR
	at org.apache.tajo.TajoTestingCluster.waitForQueryState(TajoTestingCluster.java:751)
	at org.apache.tajo.querymaster.TestKillQuery.testKillQueryFromInitState(TestKillQuery.java:135)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:497)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
	at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
	at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:264)
	at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:153)
	at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:124)
	at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:200)
	at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:153)
	at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:103)
Stage: [eb_1446498795879_0000_000003] (Total: 1, Complete: 1, Success: 0, Killed: 0, Failed: 0)
2015-11-02 21:13:26,208 INFO: org.apache.tajo.querymaster.QueryMasterTask (serviceStop(172)) - Stopping QueryMasterTask:q_1446498795879_0000
2015-11-02 21:13:26,209 INFO: org.apache.tajo.querymaster.QueryMasterTask (cleanupQuery(473)) - Cleanup resources of all workers. Query: q_1446498795879_0000, workers: 0
2015-11-02 21:13:26,212 INFO: org.apache.tajo.querymaster.QueryMasterTask (serviceStop(188)) - Stopped QueryMasterTask:q_1446498795879_0000
2015-11-02 21:13:26,222 INFO: org.apache.tajo.session.SessionManager (removeSession(85)) - Session b628eaf7-768d-43aa-bd48-82247ae9b44c is removed.