diff --git a/include/libs/qworker/qworker.h b/include/libs/qworker/qworker.h
index 91cf975a56660cd13a9fac992cb59c79bd2362b4..aa20082fe02c75c74306adcbdbddc250384ac116 100644
--- a/include/libs/qworker/qworker.h
+++ b/include/libs/qworker/qworker.h
@@ -58,6 +58,8 @@ typedef struct {
 
 int32_t qWorkerInit(int8_t nodeType, int32_t nodeId, SQWorkerCfg *cfg, void **qWorkerMgmt, const SMsgCb *pMsgCb);
 
+int32_t qWorkerPreprocessQueryMsg(void *qWorkerMgmt, SRpcMsg *pMsg);
+
 int32_t qWorkerProcessQueryMsg(void *node, void *qWorkerMgmt, SRpcMsg *pMsg, int64_t ts);
 
 int32_t qWorkerProcessCQueryMsg(void *node, void *qWorkerMgmt, SRpcMsg *pMsg, int64_t ts);
diff --git a/include/util/taoserror.h b/include/util/taoserror.h
index 4550bccbedc3b53e6882ad05f11d41677674f474..0e1fd33e839b6be1e07c7b72f98ae922823f71bd 100644
--- a/include/util/taoserror.h
+++ b/include/util/taoserror.h
@@ -563,7 +563,8 @@ int32_t* taosGetErrno();
 //scheduler&qworker
 #define TSDB_CODE_SCH_STATUS_ERROR              TAOS_DEF_ERROR_CODE(0, 0x2501)
 #define TSDB_CODE_SCH_INTERNAL_ERROR            TAOS_DEF_ERROR_CODE(0, 0x2502)
-#define TSDB_CODE_QW_MSG_ERROR                  TAOS_DEF_ERROR_CODE(0, 0x2503)
+#define TSDB_CODE_SCH_IGNORE_ERROR              TAOS_DEF_ERROR_CODE(0, 0x2503)
+#define TSDB_CODE_QW_MSG_ERROR                  TAOS_DEF_ERROR_CODE(0, 0x2504)
 
 //parser
 #define TSDB_CODE_PAR_SYNTAX_ERROR              TAOS_DEF_ERROR_CODE(0, 0x2600)
diff --git a/source/client/src/clientEnv.c b/source/client/src/clientEnv.c
index 4f5f23b68be93ca3449ddbc2ffd3522c1d1cd27c..a4655f7bcdc6006c8cfc7bf41ab7090a8f754334 100644
--- a/source/client/src/clientEnv.c
+++ b/source/client/src/clientEnv.c
@@ -131,6 +131,7 @@ void destroyTscObj(void *pObj) {
   hbDeregisterConn(pTscObj->pAppInfo->pAppHbMgr, connKey);
   atomic_sub_fetch_64(&pTscObj->pAppInfo->numOfConns, 1);
   closeAllRequests(pTscObj->pRequests);
+  schedulerStopTransport(pTscObj->pAppInfo->pTransporter);
   tscDebug("connObj 0x%" PRIx64 " destroyed, totalConn:%" PRId64, pTscObj->id, pTscObj->pAppInfo->numOfConns);
   taosThreadMutexDestroy(&pTscObj->mutex);
   taosMemoryFreeClear(pTscObj);
diff --git a/source/dnode/mgmt/mgmt_vnode/src/vmWorker.c b/source/dnode/mgmt/mgmt_vnode/src/vmWorker.c
index a945358d342f373f1ec4bda4659ea3008c9a2383..378451c301cb1c874382ae3f042f572d7a70c468 100644
--- a/source/dnode/mgmt/mgmt_vnode/src/vmWorker.c
+++ b/source/dnode/mgmt/mgmt_vnode/src/vmWorker.c
@@ -238,6 +238,8 @@ static int32_t vmPutNodeMsgToQueue(SVnodeMgmt *pMgmt, SRpcMsg *pMsg, EQueueType
 
   switch (qtype) {
     case QUERY_QUEUE:
+      vnodePreprocessQueryMsg(pVnode->pImpl, pMsg);
+      
       dTrace("msg:%p, put into vnode-query worker, type:%s", pMsg, TMSG_INFO(pMsg->msgType));
       taosWriteQitem(pVnode->pQueryQ, pMsg);
       break;
diff --git a/source/dnode/vnode/inc/vnode.h b/source/dnode/vnode/inc/vnode.h
index 308f89736d2e1efd2263a8a6c130cc059574d243..c3016eeff753d989dda58056fa508eb5f7770f0f 100644
--- a/source/dnode/vnode/inc/vnode.h
+++ b/source/dnode/vnode/inc/vnode.h
@@ -56,6 +56,7 @@ int32_t vnodePreprocessReq(SVnode *pVnode, SRpcMsg *pMsg);
 int32_t vnodeProcessWriteReq(SVnode *pVnode, SRpcMsg *pMsg, int64_t version, SRpcMsg *pRsp);
 int32_t vnodeProcessCMsg(SVnode *pVnode, SRpcMsg *pMsg, SRpcMsg **pRsp);
 int32_t vnodeProcessSyncReq(SVnode *pVnode, SRpcMsg *pMsg, SRpcMsg **pRsp);
+int32_t vnodePreprocessQueryMsg(SVnode * pVnode, SRpcMsg * pMsg);
 int32_t vnodeProcessQueryMsg(SVnode *pVnode, SRpcMsg *pMsg);
 int32_t vnodeProcessFetchMsg(SVnode *pVnode, SRpcMsg *pMsg, SQueueInfo *pInfo);
 int32_t vnodeGetLoad(SVnode *pVnode, SVnodeLoad *pLoad);
diff --git a/source/dnode/vnode/src/vnd/vnodeSvr.c b/source/dnode/vnode/src/vnd/vnodeSvr.c
index ab879c5dbbbff95a663747d8c1ce09f987f5dc8f..82a174025bf180eaeea092c30577571b35564c17 100644
--- a/source/dnode/vnode/src/vnd/vnodeSvr.c
+++ b/source/dnode/vnode/src/vnd/vnodeSvr.c
@@ -189,7 +189,15 @@ _err:
   return -1;
 }
 
-int vnodeProcessQueryMsg(SVnode *pVnode, SRpcMsg *pMsg) {
+int32_t vnodePreprocessQueryMsg(SVnode * pVnode, SRpcMsg * pMsg) {
+  if (TDMT_VND_QUERY != pMsg->msgType) {
+    return 0;
+  }
+
+  return qWorkerPreprocessQueryMsg(pVnode->pQuery, pMsg);
+}
+
+int32_t vnodeProcessQueryMsg(SVnode *pVnode, SRpcMsg *pMsg) {
   vTrace("message in vnode query queue is processing");
   SReadHandle handle = {.meta = pVnode->pMeta, .config = &pVnode->config, .vnode = pVnode, .pMsgCb = &pVnode->msgCb};
   switch (pMsg->msgType) {
diff --git a/source/libs/qworker/inc/qwInt.h b/source/libs/qworker/inc/qwInt.h
index 4fe3c1839310be9e264f7241fbc0cce48837a05c..3804c114cb39f53fd5f2206f36537394073e587d 100644
--- a/source/libs/qworker/inc/qwInt.h
+++ b/source/libs/qworker/inc/qwInt.h
@@ -33,7 +33,7 @@ extern "C" {
 #define QW_DEFAULT_TASK_NUMBER      10000
 #define QW_DEFAULT_SCH_TASK_NUMBER  10000
 #define QW_DEFAULT_SHORT_RUN_TIMES  2
-#define QW_DEFAULT_HEARTBEAT_MSEC   3000
+#define QW_DEFAULT_HEARTBEAT_MSEC   5000
 
 enum {
   QW_PHASE_PRE_QUERY = 1,
diff --git a/source/libs/qworker/inc/qwMsg.h b/source/libs/qworker/inc/qwMsg.h
index ede085b6f912842c85dce8597374613856d80f1f..5a8a45cd5150bc5e2aa009f2f3690e8f98a14c05 100644
--- a/source/libs/qworker/inc/qwMsg.h
+++ b/source/libs/qworker/inc/qwMsg.h
@@ -23,6 +23,7 @@ extern "C" {
 #include "qwInt.h"
 #include "dataSinkMgt.h"
 
+int32_t qwPrerocessQuery(QW_FPARAMS_DEF, SQWMsg *qwMsg);
 int32_t qwProcessQuery(QW_FPARAMS_DEF, SQWMsg *qwMsg, int8_t taskType, int8_t explain);
 int32_t qwProcessCQuery(QW_FPARAMS_DEF, SQWMsg *qwMsg);
 int32_t qwProcessReady(QW_FPARAMS_DEF, SQWMsg *qwMsg);
diff --git a/source/libs/qworker/src/qwMsg.c b/source/libs/qworker/src/qwMsg.c
index f8205a6bb4b2d004bc1c4f35b67eabc5635c5ca7..79fcbc407976a0b91441cb5c5b0527e9ec6f96a5 100644
--- a/source/libs/qworker/src/qwMsg.c
+++ b/source/libs/qworker/src/qwMsg.c
@@ -248,6 +248,41 @@ int32_t qwRegisterHbBrokenLinkArg(SQWorker *mgmt, uint64_t sId, SRpcHandleInfo *
   return TSDB_CODE_SUCCESS;
 }
 
+int32_t qWorkerPreprocessQueryMsg(void *qWorkerMgmt, SRpcMsg *pMsg) {
+  if (NULL == qWorkerMgmt || NULL == pMsg) {
+    QW_ERR_RET(TSDB_CODE_QRY_INVALID_INPUT);
+  }
+
+  int32_t       code = 0;
+  SSubQueryMsg *msg = pMsg->pCont;
+  SQWorker *    mgmt = (SQWorker *)qWorkerMgmt;
+
+  if (NULL == msg || pMsg->contLen <= sizeof(*msg)) {
+    QW_ELOG("invalid query msg, msg:%p, msgLen:%d", msg, pMsg->contLen);
+    QW_ERR_RET(TSDB_CODE_QRY_INVALID_INPUT);
+  }
+
+  msg->sId = be64toh(msg->sId);
+  msg->queryId = be64toh(msg->queryId);
+  msg->taskId = be64toh(msg->taskId);
+  msg->refId = be64toh(msg->refId);
+  msg->phyLen = ntohl(msg->phyLen);
+  msg->sqlLen = ntohl(msg->sqlLen);
+
+  uint64_t sId = msg->sId;
+  uint64_t qId = msg->queryId;
+  uint64_t tId = msg->taskId;
+  int64_t  rId = msg->refId;
+
+  SQWMsg qwMsg = {.node = node, .msg = msg->msg + msg->sqlLen, .msgLen = msg->phyLen, .connInfo = pMsg->info};
+
+  QW_SCH_TASK_DLOG("prerocessQuery start, handle:%p", pMsg->info.handle);
+  QW_ERR_RET(qwPrerocessQuery(QW_FPARAMS(), &qwMsg));
+  QW_SCH_TASK_DLOG("prerocessQuery end, handle:%p", pMsg->info.handle);
+
+  return TSDB_CODE_SUCCESS;
+}
+
 int32_t qWorkerProcessQueryMsg(void *node, void *qWorkerMgmt, SRpcMsg *pMsg, int64_t ts) {
   if (NULL == node || NULL == qWorkerMgmt || NULL == pMsg) {
     QW_ERR_RET(TSDB_CODE_QRY_INVALID_INPUT);
diff --git a/source/libs/qworker/src/qworker.c b/source/libs/qworker/src/qworker.c
index fd16fa53b7a6d9b4c5e460719c3fc09134ef034b..9ad36a32c4716fc44091de4686fdaf10162dc8eb 100644
--- a/source/libs/qworker/src/qworker.c
+++ b/source/libs/qworker/src/qworker.c
@@ -248,11 +248,7 @@ int32_t qwHandlePrePhaseEvents(QW_FPARAMS_DEF, int8_t phase, SQWPhaseInput *inpu
 
   QW_TASK_DLOG("start to handle event at phase %s", qwPhaseStr(phase));
 
-  if (QW_PHASE_PRE_QUERY == phase) {
-    QW_ERR_JRET(qwAddAcquireTaskCtx(QW_FPARAMS(), &ctx));
-  } else {
-    QW_ERR_JRET(qwAcquireTaskCtx(QW_FPARAMS(), &ctx));
-  }
+  QW_ERR_JRET(qwAcquireTaskCtx(QW_FPARAMS(), &ctx));
 
   QW_LOCK(QW_WRITE, &ctx->lock);
 
@@ -285,7 +281,7 @@ int32_t qwHandlePrePhaseEvents(QW_FPARAMS_DEF, int8_t phase, SQWPhaseInput *inpu
         break;
       }
 
-      QW_ERR_JRET(qwAddTaskStatus(QW_FPARAMS(), JOB_TASK_STATUS_EXECUTING));
+      QW_ERR_JRET(qwUpdateTaskStatus(QW_FPARAMS(), JOB_TASK_STATUS_EXECUTING));
       break;
     }
     case QW_PHASE_PRE_FETCH: {
@@ -437,7 +433,7 @@ _return:
   QW_RET(code);
 }
 
-int32_t qwProcessQuery(QW_FPARAMS_DEF, SQWMsg *qwMsg, int8_t taskType, int8_t explain) {
+int32_t qwPrerocessQuery(QW_FPARAMS_DEF, SQWMsg *qwMsg) {
   int32_t        code = 0;
   bool           queryRsped = false;
   SSubplan      *plan = NULL;
@@ -448,6 +444,30 @@ int32_t qwProcessQuery(QW_FPARAMS_DEF, SQWMsg *qwMsg, int8_t taskType, int8_t ex
 
   QW_ERR_JRET(qwRegisterQueryBrokenLinkArg(QW_FPARAMS(), &qwMsg->connInfo));
 
+  QW_ERR_JRET(qwAddAcquireTaskCtx(QW_FPARAMS(), &ctx));
+
+  QW_ERR_JRET(qwAddTaskStatus(QW_FPARAMS(), JOB_TASK_STATUS_NOT_START));
+
+_return:
+
+  if (ctx) {
+    QW_UPDATE_RSP_CODE(ctx, code);
+    qwReleaseTaskCtx(mgmt, ctx);
+  }
+
+  QW_RET(TSDB_CODE_SUCCESS);
+}
+
+
+int32_t qwProcessQuery(QW_FPARAMS_DEF, SQWMsg *qwMsg, int8_t taskType, int8_t explain) {
+  int32_t        code = 0;
+  bool           queryRsped = false;
+  SSubplan      *plan = NULL;
+  SQWPhaseInput  input = {0};
+  qTaskInfo_t    pTaskInfo = NULL;
+  DataSinkHandle sinkHandle = NULL;
+  SQWTaskCtx    *ctx = NULL;
+
   QW_ERR_JRET(qwHandlePrePhaseEvents(QW_FPARAMS(), QW_PHASE_PRE_QUERY, &input, NULL));
 
   QW_ERR_JRET(qwGetTaskCtx(QW_FPARAMS(), &ctx));
@@ -663,7 +683,7 @@ int32_t qwProcessDrop(QW_FPARAMS_DEF, SQWMsg *qwMsg) {
 
   // TODO : TASK ALREADY REMOVED AND A NEW DROP MSG RECEIVED
 
-  QW_ERR_JRET(qwAddAcquireTaskCtx(QW_FPARAMS(), &ctx));
+  QW_ERR_JRET(qwAcquireTaskCtx(QW_FPARAMS(), &ctx));
 
   QW_LOCK(QW_WRITE, &ctx->lock);
 
diff --git a/source/libs/scheduler/inc/schedulerInt.h b/source/libs/scheduler/inc/schedulerInt.h
index 44b3e6d396b8750a78ba9e414243f45686a121ec..709f3a4e34b4b655fc06697f14f012ee2a0cd85d 100644
--- a/source/libs/scheduler/inc/schedulerInt.h
+++ b/source/libs/scheduler/inc/schedulerInt.h
@@ -32,6 +32,10 @@ extern "C" {
 #define SCHEDULE_DEFAULT_MAX_TASK_NUM 1000
 #define SCHEDULE_DEFAULT_MAX_NODE_TABLE_NUM 200  // unit is TSDB_TABLE_NUM_UNIT
 
+#define SCH_DEFAULT_TASK_TIMEOUT_USEC 10000000
+#define SCH_MAX_TASK_TIMEOUT_USEC 60000000
+
+#define SCH_TASK_MAX_EXEC_TIMES 5
 #define SCH_MAX_CANDIDATE_EP_NUM TSDB_MAX_REPLICA
 
 enum {
@@ -51,6 +55,7 @@ typedef struct SSchTrans {
 
 typedef struct SSchHbTrans {
   SRWLatch  lock;
+  int64_t   taskNum;
   SRpcCtx   rpcCtx;
   SSchTrans trans;
 } SSchHbTrans;
@@ -114,7 +119,8 @@ typedef struct SSchTaskCallbackParam {
   uint64_t                queryId;
   int64_t                 refId;
   uint64_t                taskId;
-  void                   *transport;
+  int32_t                 execIdx;
+  void                   *pTrans;
 } SSchTaskCallbackParam;
 
 typedef struct SSchHbCallbackParam {
@@ -148,8 +154,16 @@ typedef struct SSchLevel {
   SArray         *subTasks;      // Element is SQueryTask
 } SSchLevel;
 
+typedef struct SSchTaskProfile {
+  int64_t startTs;
+  int64_t execUseTime[SCH_TASK_MAX_EXEC_TIMES];
+  int64_t waitTime;
+  int64_t endTs;
+} SSchTaskProfile;
+
 typedef struct SSchTask {
   uint64_t             taskId;         // task id
+  int32_t              execIdx;        // task current execute try index
   SRWLatch             lock;           // task lock
   SSchLevel           *level;          // level
   SSubplan            *plan;           // subplan
@@ -157,16 +171,17 @@ typedef struct SSchTask {
   int32_t              msgLen;         // msg length
   int8_t               status;         // task status
   int32_t              lastMsgType;    // last sent msg type
-  int32_t              tryTimes;       // task already tried times
+  int64_t              timeoutUsec;    // taks timeout useconds before reschedule
   SQueryNodeAddr       succeedAddr;    // task executed success node address
   int8_t               candidateIdx;   // current try condidation index
   SArray              *candidateAddrs; // condidate node addresses, element is SQueryNodeAddr
-  SArray              *execNodes;      // all tried node for current task, element is SSchNodeInfo
-  SQueryProfileSummary summary;        // task execution summary
+  SHashObj            *execNodes;      // all tried node for current task, element is SSchNodeInfo
+  SSchTaskProfile      profile;        // task execution profile
   int32_t              childReady;     // child task ready number
   SArray              *children;       // the datasource tasks,from which to fetch the result, element is SQueryTask*
   SArray              *parents;        // the data destination tasks, get data from current task, element is SQueryTask*
-  void*                handle;          // task send handle 
+  void*                handle;         // task send handle 
+  bool                 registerdHb;    // registered in hb
 } SSchTask;
 
 typedef struct SSchJobAttr {
@@ -215,6 +230,24 @@ typedef struct SSchJob {
 
 extern SSchedulerMgmt schMgmt;
 
+#define SCH_LOG_TASK_START_TS(_task)                      \
+  do {                                                    \
+    int64_t us = taosGetTimestampUs();                    \
+    (_task)->profile.tryUseTime[(_task)->execIdx] = us;    \
+    if (0 == (_task)->execIdx) {                           \
+      (_task)->profile.startTs = us;                      \
+    }                                                     \
+  } while (0)  
+
+#define SCH_LOG_TASK_END_TS(_task)                        \
+  do {                                                    \
+    int64_t us = taosGetTimestampUs();                    \
+    (_task)->profile.tryUseTime[(_task)->execIdx] = us - (_task)->profile.tryUseTime[(_task)->execIdx];    \
+    (_task)->profile.endTs = us;                          \
+  } while (0)  
+
+#define SCH_TASK_TIMEOUT(_task) ((taosGetTimestampUs() - (_task)->profile.tryUseTime[(_task)->execIdx]) > (_taks)->timeoutUsec)
+
 #define SCH_TASK_READY_FOR_LAUNCH(readyNum, task) ((readyNum) >= taosArrayGetSize((task)->children))
 
 #define SCH_TASK_ID(_task) ((_task) ? (_task)->taskId : -1)
@@ -284,7 +317,7 @@ int32_t schLaunchTasksInFlowCtrlList(SSchJob *pJob, SSchTask *pTask);
 int32_t schLaunchTaskImpl(SSchJob *pJob, SSchTask *pTask);
 int32_t schFetchFromRemote(SSchJob *pJob);
 int32_t schProcessOnTaskFailure(SSchJob *pJob, SSchTask *pTask, int32_t errCode);
-int32_t schBuildAndSendHbMsg(SQueryNodeEpId *nodeEpId);
+int32_t schBuildAndSendHbMsg(SQueryNodeEpId *nodeEpId, SArray* taskAction);
 int32_t schCloneSMsgSendInfo(void *src, void **dst);
 int32_t schValidateAndBuildJob(SQueryPlan *pDag, SSchJob *pJob);
 void schFreeJobImpl(void *job);
@@ -301,10 +334,9 @@ int32_t schSaveJobQueryRes(SSchJob *pJob, SQueryTableRsp *rsp);
 int32_t schProcessOnExplainDone(SSchJob *pJob, SSchTask *pTask, SRetrieveTableRsp *pRsp);
 void schProcessOnDataFetched(SSchJob *job);
 int32_t schGetTaskInJob(SSchJob *pJob, uint64_t taskId, SSchTask **pTask);
-int32_t schUpdateTaskExecNodeHandle(SSchTask *pTask, void *handle, int32_t rspCode);
 void schFreeRpcCtxVal(const void *arg);
 int32_t schMakeBrokenLinkVal(SSchJob *pJob, SSchTask *pTask, SRpcBrokenlinkVal *brokenVal, bool isHb);
-int32_t schRecordTaskExecNode(SSchJob *pJob, SSchTask *pTask, SQueryNodeAddr *addr, void *handle);
+int32_t schAppendTaskExecNode(SSchJob *pJob, SSchTask *pTask, SQueryNodeAddr *addr, int32_t execIdx);
 int32_t schExecStaticExplainJob(void *pTrans, SArray *pNodeList, SQueryPlan *pDag, int64_t *job, const char *sql,
                              SSchResInfo *pRes, bool sync);
 int32_t schExecJobImpl(void *pTrans, SArray *pNodeList, SQueryPlan *pDag, int64_t *job, const char *sql,
@@ -318,7 +350,7 @@ int32_t schExecJob(void *pTrans, SArray *pNodeList, SQueryPlan *pDag, int64_t *p
 int32_t schAsyncExecJob(void *pTrans, SArray *pNodeList, SQueryPlan *pDag, int64_t *pJob, const char *sql, int64_t startTs, SSchResInfo *pRes);
 int32_t schFetchRows(SSchJob *pJob);
 int32_t schAsyncFetchRows(SSchJob *pJob);
-int32_t schUpdateTaskHandle(SSchJob *pJob, SSchTask *pTask, int32_t msgType, void *handle, int32_t rspCode);
+int32_t schUpdateTaskHandle(SSchJob *pJob, SSchTask *pTask, int32_t msgType, void *handle, int32_t execIdx);
 
 
 #ifdef __cplusplus
diff --git a/source/libs/scheduler/src/schJob.c b/source/libs/scheduler/src/schJob.c
index dbad053c65ba3572a6d4740e4b991f3760e9631b..7600dafa59dab41e0def1c6d4563e5410f07744f 100644
--- a/source/libs/scheduler/src/schJob.c
+++ b/source/libs/scheduler/src/schJob.c
@@ -28,11 +28,13 @@ FORCE_INLINE int32_t schReleaseJob(int64_t refId) { return taosReleaseRef(schMgm
 int32_t schInitTask(SSchJob *pJob, SSchTask *pTask, SSubplan *pPlan, SSchLevel *pLevel) {
   pTask->plan = pPlan;
   pTask->level = pLevel;
+  pTask->execIdx = -1;
+  pTask->timeoutUsec = SCH_DEFAULT_TASK_TIMEOUT_USEC;
   SCH_SET_TASK_STATUS(pTask, JOB_TASK_STATUS_NOT_START);
   pTask->taskId = schGenTaskId();
-  pTask->execNodes = taosArrayInit(SCH_MAX_CANDIDATE_EP_NUM, sizeof(SSchNodeInfo));
+  pTask->execNodes = taosHashInit(SCH_MAX_CANDIDATE_EP_NUM, taosGetDefaultHashFunction(TSDB_DATA_TYPE_INT), true, HASH_NO_LOCK);
   if (NULL == pTask->execNodes) {
-    SCH_TASK_ELOG("taosArrayInit %d execNodes failed", SCH_MAX_CANDIDATE_EP_NUM);
+    SCH_TASK_ELOG("taosHashInit %d execNodes failed", SCH_MAX_CANDIDATE_EP_NUM);
     SCH_ERR_RET(TSDB_CODE_QRY_OUT_OF_MEMORY);
   }
 
@@ -123,7 +125,33 @@ _return:
   SCH_RET(code);
 }
 
-void schFreeTask(SSchTask *pTask) {
+void schDeregisterTaskHb(SSchJob *pJob, SSchTask *pTask) {
+  if (!pTask->registerdHb) {
+    return;
+  }
+  
+  SQueryNodeAddr *addr = taosArrayGet(pTask->candidateAddrs, pTask->candidateIdx);
+  SQueryNodeEpId  epId = {0};
+
+  epId.nodeId = addr->nodeId;
+
+  SEp* pEp = SCH_GET_CUR_EP(addr);
+  strcpy(epId.ep.fqdn, pEp->fqdn);
+  epId.ep.port = pEp->port;
+
+  SSchHbTrans *hb = taosHashGet(schMgmt.hbConnections, &epId, sizeof(SQueryNodeEpId));
+  if (NULL == hb) {
+    SCH_TASK_ELOG("nodeId %d fqdn %s port %d not in hb connections", epId.nodeId, epId.ep.fqdn, epId.ep.port);
+  }
+
+  atomic_sub_fetch_64(&hb->taskNum, 1);
+  
+  pTask->registerdHb = false;
+}
+
+void schFreeTask(SSchJob *pJob, SSchTask *pTask) {
+  schDeregisterTaskHb(pJob, pTask);
+  
   if (pTask->candidateAddrs) {
     taosArrayDestroy(pTask->candidateAddrs);
   }
@@ -139,7 +167,7 @@ void schFreeTask(SSchTask *pTask) {
   }
 
   if (pTask->execNodes) {
-    taosArrayDestroy(pTask->execNodes);
+    taosHashCleanup(pTask->execNodes);
   }
 }
 
@@ -329,45 +357,52 @@ int32_t schRecordTaskSucceedNode(SSchJob *pJob, SSchTask *pTask) {
   return TSDB_CODE_SUCCESS;
 }
 
-int32_t schRecordTaskExecNode(SSchJob *pJob, SSchTask *pTask, SQueryNodeAddr *addr, void *handle) {
-  SSchNodeInfo nodeInfo = {.addr = *addr, .handle = handle};
+int32_t schAppendTaskExecNode(SSchJob *pJob, SSchTask *pTask, SQueryNodeAddr *addr, int32_t execIdx) {
+  SSchNodeInfo nodeInfo = {.addr = *addr, .handle = NULL};
 
-  if (NULL == taosArrayPush(pTask->execNodes, &nodeInfo)) {
-    SCH_TASK_ELOG("taosArrayPush nodeInfo to execNodes list failed, errno:%d", errno);
+  if (NULL == taosHashPut(pTask->execNodes, &execIdx, sizeof(execIdx), &nodeInfo, sizeof(nodeInfo))) {
+    SCH_TASK_ELOG("taosHashPut nodeInfo to execNodes failed, errno:%d", errno);
     SCH_ERR_RET(TSDB_CODE_QRY_OUT_OF_MEMORY);
   }
 
-  SCH_TASK_DLOG("task execNode recorded, handle:%p", handle);
+  SCH_TASK_DLOG("task execNode added, execIdx:%d", execIdx);
 
   return TSDB_CODE_SUCCESS;
 }
 
-int32_t schDropTaskExecNode(SSchJob *pJob, SSchTask *pTask, void *handle) {
+int32_t schDropTaskExecNode(SSchJob *pJob, SSchTask *pTask, void *handle, int32_t execIdx) {
   if (NULL == pTask->execNodes) {
     return TSDB_CODE_SUCCESS;
   }
 
-  int32_t num = taosArrayGetSize(pTask->execNodes);
-  for (int32_t i = 0; i < num; ++i) {
-    SSchNodeInfo* pNode = taosArrayGet(pTask->execNodes, i);
-    if (pNode->handle == handle) {
-      taosArrayRemove(pTask->execNodes, i);
-      break;
-    }
+  taosHashRemove(pTask->execNodes, &execIdx, sizeof(execIdx));
+  if (execIdx != pTask->execIdx) {     // ignore it
+    SCH_RET(TSDB_CODE_SCH_IGNORE_ERROR);
   }
 
   return TSDB_CODE_SUCCESS;
 }
 
-int32_t schUpdateTaskHandle(SSchJob *pJob, SSchTask *pTask, int32_t msgType, void *handle, int32_t rspCode) {
-  SCH_SET_TASK_HANDLE(pTask, handle);
+int32_t schUpdateTaskExecNode(SSchTask *pTask, void *handle, int32_t execIdx) {
+  if (taosArrayGetSize(pTask->execNodes) <= 0) {
+    return TSDB_CODE_SUCCESS;
+  }
 
-  schUpdateTaskExecNodeHandle(pTask, handle, rspCode);
+  SSchNodeInfo *nodeInfo = taosHashGet(pTask->execNodes, &execIdx, sizeof(execIdx));
+  nodeInfo->handle = handle;
+
+  return TSDB_CODE_SUCCESS;
+}
 
+int32_t schUpdateTaskHandle(SSchJob *pJob, SSchTask *pTask, int32_t msgType, void *handle, int32_t execIdx) {
   if (msgType == TDMT_SCH_LINK_BROKEN) {
-    schDropTaskExecNode(pJob, pTask, handle);
+    SCH_RET(schDropTaskExecNode(pJob, pTask, handle, execIdx));
   }
 
+  SCH_SET_TASK_HANDLE(pTask, handle);
+
+  schUpdateTaskExecNode(pTask, handle, execIdx);
+
   return TSDB_CODE_SUCCESS;
 }
 
@@ -672,7 +707,6 @@ int32_t schMoveTaskToExecList(SSchJob *pJob, SSchTask *pTask, bool *moved) {
 
 int32_t schTaskCheckSetRetry(SSchJob *pJob, SSchTask *pTask, int32_t errCode, bool *needRetry) {
   int8_t status = 0;
-  ++pTask->tryTimes;
 
   if (schJobNeedToStop(pJob, &status)) {
     *needRetry = false;
@@ -680,9 +714,9 @@ int32_t schTaskCheckSetRetry(SSchJob *pJob, SSchTask *pTask, int32_t errCode, bo
     return TSDB_CODE_SUCCESS;
   }
 
-  if (pTask->tryTimes >= REQUEST_MAX_TRY_TIMES) {
+  if ((pTask->execIdx + 1) >= SCH_TASK_MAX_EXEC_TIMES) {
     *needRetry = false;
-    SCH_TASK_DLOG("task no more retry since reach max try times, tryTimes:%d", pTask->tryTimes);
+    SCH_TASK_DLOG("task no more retry since reach max try times, execIdx:%d", pTask->execIdx);
     return TSDB_CODE_SUCCESS;
   }
 
@@ -694,9 +728,9 @@ int32_t schTaskCheckSetRetry(SSchJob *pJob, SSchTask *pTask, int32_t errCode, bo
 
   // TODO CHECK epList/condidateList
   if (SCH_IS_DATA_SRC_TASK(pTask)) {
-    if (pTask->tryTimes >= SCH_TASK_NUM_OF_EPS(&pTask->plan->execNode)) {
+    if ((pTask->execIdx + 1) >= SCH_TASK_NUM_OF_EPS(&pTask->plan->execNode)) {
       *needRetry = false;
-      SCH_TASK_DLOG("task no more retry since all ep tried, tryTimes:%d, epNum:%d", pTask->tryTimes,
+      SCH_TASK_DLOG("task no more retry since all ep tried, execIdx:%d, epNum:%d", pTask->execIdx,
                     SCH_TASK_NUM_OF_EPS(&pTask->plan->execNode));
       return TSDB_CODE_SUCCESS;
     }
@@ -712,7 +746,7 @@ int32_t schTaskCheckSetRetry(SSchJob *pJob, SSchTask *pTask, int32_t errCode, bo
   }
 
   *needRetry = true;
-  SCH_TASK_DLOG("task need the %dth retry, errCode:%x - %s", pTask->tryTimes, errCode, tstrerror(errCode));
+  SCH_TASK_DLOG("task need the %dth retry, errCode:%x - %s", pTask->execIdx + 1, errCode, tstrerror(errCode));
 
   return TSDB_CODE_SUCCESS;
 }
@@ -728,6 +762,8 @@ int32_t schHandleTaskRetry(SSchJob *pJob, SSchTask *pTask) {
     SCH_ERR_RET(schLaunchTasksInFlowCtrlList(pJob, pTask));
   }
 
+  schDeregisterTaskHb(pJob, pTask);
+
   if (SCH_IS_DATA_SRC_TASK(pTask)) {
     SCH_SWITCH_EPSET(&pTask->plan->execNode);
   } else {
@@ -906,6 +942,8 @@ void schProcessOnDataFetched(SSchJob *job) {
 int32_t schProcessOnTaskFailure(SSchJob *pJob, SSchTask *pTask, int32_t errCode) {
   int8_t status = 0;
 
+  SCH_LOG_TASK_END_TS(pTask);
+
   if (schJobNeedToStop(pJob, &status)) {
     SCH_TASK_DLOG("task failed not processed cause of job status, job status:%s", jobTaskStatusStr(status));
     SCH_RET(atomic_load_32(&pJob->errCode));
@@ -989,6 +1027,8 @@ int32_t schProcessOnTaskSuccess(SSchJob *pJob, SSchTask *pTask) {
 
   SCH_TASK_DLOG("taskOnSuccess, status:%s", SCH_GET_TASK_STATUS_STR(pTask));
 
+  SCH_LOG_TASK_END_TS(pTask);
+
   SCH_ERR_JRET(schMoveTaskToSuccList(pJob, pTask, &moved));
 
   SCH_SET_TASK_STATUS(pTask, JOB_TASK_STATUS_PARTIAL_SUCCEED);
@@ -1105,6 +1145,57 @@ int32_t schProcessOnExplainDone(SSchJob *pJob, SSchTask *pTask, SRetrieveTableRs
   return TSDB_CODE_SUCCESS;
 }
 
+int32_t schRescheduleTask(SSchJob *pJob, SSchTask *pTask) {
+  if (SCH_IS_DATA_SRC_QRY_TASK(pTask)) {
+    return TSDB_CODE_SUCCESS;
+  }
+
+  
+}
+
+int32_t schProcessOnTaskStatusRsp(SQueryNodeEpId* pEpId, SArray* pStatusList) {
+  int32_t taskNum = (int32_t)taosArrayGetSize(pStatusList);
+  SSchTask *pTask = NULL;
+
+  qDebug("%d task status in hb rsp from nodeId:%d, fqdn:%s, port:%d", taskNum, pEpId->nodeId, pEpId->ep.fqdn, pEpId->ep.port);
+
+  for (int32_t i = 0; i < taskNum; ++i) {
+    STaskStatus *taskStatus = taosArrayGet(pStatusList, i);
+
+    SSchJob *pJob = schAcquireJob(taskStatus->refId);
+    if (NULL == pJob) {
+      qWarn("job not found, refId:0x%" PRIx64 ",QID:0x%" PRIx64 ",TID:0x%" PRIx64, taskStatus->refId,
+            taskStatus->queryId, taskStatus->taskId);
+      // TODO DROP TASK FROM SERVER!!!!
+      continue;
+    }
+
+    SCH_JOB_DLOG("TID:0x%" PRIx64 " task status in server: %s", taskStatus->taskId, jobTaskStatusStr(taskStatus->status));
+
+    pTask = NULL;
+    schGetTaskInJob(pJob, taskStatus->taskId, &pTask);
+    if (NULL == pTask) {
+      // TODO DROP TASK FROM SERVER!!!!
+      schReleaseJob(taskStatus->refId);
+      continue;
+    }
+    
+    if (taskStatus->status == JOB_TASK_STATUS_FAILED) {
+      // RECORD AND HANDLE ERROR!!!!
+      schReleaseJob(taskStatus->refId);
+      continue;
+    }
+
+    if (taskStatus->status == JOB_TASK_STATUS_NOT_START && SCH_TASK_TIMEOUT(pTask)) {
+      schRescheduleTask(pJob, pTask);
+    }
+
+    schReleaseJob(taskStatus->refId);
+  }
+
+}
+
+
 int32_t schSaveJobQueryRes(SSchJob *pJob, SQueryTableRsp *rsp) {
   if (rsp->tbFName[0]) {
     if (NULL == pJob->execRes.res) {
@@ -1156,25 +1247,16 @@ int32_t schGetTaskInJob(SSchJob *pJob, uint64_t taskId, SSchTask **pTask) {
   return TSDB_CODE_SUCCESS;
 }
 
-
-int32_t schUpdateTaskExecNodeHandle(SSchTask *pTask, void *handle, int32_t rspCode) {
-  if (rspCode || NULL == pTask->execNodes || taosArrayGetSize(pTask->execNodes) > 1 ||
-      taosArrayGetSize(pTask->execNodes) <= 0) {
-    return TSDB_CODE_SUCCESS;
-  }
-
-  SSchNodeInfo *nodeInfo = taosArrayGet(pTask->execNodes, 0);
-  nodeInfo->handle = handle;
-
-  return TSDB_CODE_SUCCESS;
-}
-
 int32_t schLaunchTaskImpl(SSchJob *pJob, SSchTask *pTask) {
   int8_t  status = 0;
   int32_t code = 0;
 
   atomic_add_fetch_32(&pTask->level->taskLaunchedNum, 1);
 
+  pTask->execIdx++;
+
+  SCH_LOG_TASK_START_TS(pTask);
+
   if (schJobNeedToStop(pJob, &status)) {
     SCH_TASK_DLOG("no need to launch task cause of job status, job status:%s", jobTaskStatusStr(status));
 
@@ -1263,19 +1345,20 @@ void schDropTaskOnExecNode(SSchJob *pJob, SSchTask *pTask) {
     return;
   }
 
-  int32_t size = (int32_t)taosArrayGetSize(pTask->execNodes);
+  int32_t size = (int32_t)taosHashGetSize(pTask->execNodes);
 
   if (size <= 0) {
     SCH_TASK_DLOG("task has no execNodes, no need to drop it, status:%s", SCH_GET_TASK_STATUS_STR(pTask));
     return;
   }
 
-  SSchNodeInfo *nodeInfo = NULL;
-  for (int32_t i = 0; i < size; ++i) {
-    nodeInfo = (SSchNodeInfo *)taosArrayGet(pTask->execNodes, i);
+  SSchNodeInfo *nodeInfo = taosHashIterate(pTask->execNodes, NULL);
+  while (nodeInfo) {
     SCH_SET_TASK_HANDLE(pTask, nodeInfo->handle);
 
     schBuildAndSendMsg(pJob, pTask, &nodeInfo->addr, TDMT_VND_DROP_TASK);
+
+    nodeInfo = taosHashIterate(pTask->execNodes, nodeInfo);
   }
 
   SCH_TASK_DLOG("task has %d exec address", size);
@@ -1332,7 +1415,7 @@ void schFreeJobImpl(void *job) {
     int32_t numOfTasks = taosArrayGetSize(pLevel->subTasks);
     for (int32_t j = 0; j < numOfTasks; ++j) {
       SSchTask *pTask = taosArrayGet(pLevel->subTasks, j);
-      schFreeTask(pTask);
+      schFreeTask(pJob, pTask);
     }
 
     taosArrayDestroy(pLevel->subTasks);
diff --git a/source/libs/scheduler/src/schRemote.c b/source/libs/scheduler/src/schRemote.c
index 0ba91a1c85649463225bd5f6d82edad4b56714c9..60384de6e0ce7cbd1e98fea7c66401893b0f2b3a 100644
--- a/source/libs/scheduler/src/schRemote.c
+++ b/source/libs/scheduler/src/schRemote.c
@@ -366,7 +366,12 @@ int32_t schHandleCallback(void *param, const SDataBuf *pMsg, int32_t msgType, in
 
   SCH_TASK_DLOG("rsp msg received, type:%s, handle:%p, code:%s", TMSG_INFO(msgType), pMsg->handle, tstrerror(rspCode));
 
-  SCH_ERR_JRET(schUpdateTaskHandle(pJob, pTask, msgType, pMsg->handle, rspCode));
+  if (pParam->execIdx != pTask->execIdx) {
+    SCH_TASK_DLOG("execIdx %d mis-match current execIdx %d", pParam->execIdx, pTask->execIdx);
+    goto _return;
+  }
+
+  SCH_ERR_JRET(schUpdateTaskHandle(pJob, pTask, msgType, pMsg->handle, pParam->execIdx));
   
   SCH_ERR_JRET(schHandleResponseMsg(pJob, pTask, msgType, pMsg->pData, pMsg->len, rspCode));
 
@@ -426,7 +431,7 @@ int32_t schHandleLinkBrokenCallback(void *param, const SDataBuf *pMsg, int32_t c
     SSchTrans            trans = {.pTrans = hbParam->pTrans, .pHandle = NULL};
     SCH_ERR_RET(schUpdateHbConnection(&hbParam->nodeEpId, &trans));
 
-    SCH_ERR_RET(schBuildAndSendHbMsg(&hbParam->nodeEpId));
+    SCH_ERR_RET(schBuildAndSendHbMsg(&hbParam->nodeEpId, NULL));
   } else {
     SCH_ERR_RET(schHandleCallback(param, pMsg, TDMT_SCH_LINK_BROKEN, code));
   }
@@ -454,7 +459,8 @@ int32_t schGenerateCallBackInfo(SSchJob *pJob, SSchTask *pTask, int32_t msgType,
   param->queryId = pJob->queryId;
   param->refId = pJob->refId;
   param->taskId = SCH_TASK_ID(pTask);
-  param->transport = pJob->pTrans;
+  param->pTrans = pJob->pTrans;
+  param->execIdx = pTask->execIdx;
 
   msgSendInfo->param = param;
   msgSendInfo->fp = fp;
@@ -717,7 +723,7 @@ int32_t schBuildAndSendHbMsg(SQueryNodeEpId *nodeEpId) {
   __async_send_cb_fn_t fp = NULL;
   SCH_ERR_JRET(schGetCallbackFp(msgType, &fp));
 
-  param->transport = trans.pTrans;
+  param->pTrans = trans.pTrans;
 
   pMsgSendInfo->param = param;
   pMsgSendInfo->msgInfo.pData = msg;
@@ -768,10 +774,14 @@ int32_t schEnsureHbConnection(SSchJob *pJob, SSchTask *pTask) {
     bool exist = false;
     SCH_ERR_RET(schRegisterHbConnection(pJob, pTask, &epId, &exist));
     if (!exist) {
-      SCH_ERR_RET(schBuildAndSendHbMsg(&epId));
+      SCH_ERR_RET(schBuildAndSendHbMsg(&epId, NULL));
     }
   }
 
+  atomic_add_fetch_64(&hb->taskNum, 1);
+  
+  pTask->registerdHb = true;
+
   return TSDB_CODE_SUCCESS;
 }
 
@@ -810,33 +820,12 @@ int32_t schHandleHbCallback(void *param, const SDataBuf *pMsg, int32_t code) {
   }
 
   SSchTrans trans = {0};
-  trans.pTrans = pParam->transport;
+  trans.pTrans = pParam->pTrans;
   trans.pHandle = pMsg->handle;
 
   SCH_ERR_JRET(schUpdateHbConnection(&rsp.epId, &trans));
 
-  int32_t taskNum = (int32_t)taosArrayGetSize(rsp.taskStatus);
-  qDebug("%d task status in hb rsp, nodeId:%d, fqdn:%s, port:%d", taskNum, rsp.epId.nodeId, rsp.epId.ep.fqdn,
-         rsp.epId.ep.port);
-
-  for (int32_t i = 0; i < taskNum; ++i) {
-    STaskStatus *taskStatus = taosArrayGet(rsp.taskStatus, i);
-
-    SSchJob *pJob = schAcquireJob(taskStatus->refId);
-    if (NULL == pJob) {
-      qWarn("job not found, refId:0x%" PRIx64 ",QID:0x%" PRIx64 ",TID:0x%" PRIx64, taskStatus->refId,
-            taskStatus->queryId, taskStatus->taskId);
-      // TODO DROP TASK FROM SERVER!!!!
-      continue;
-    }
-
-    // TODO
-
-    SCH_JOB_DLOG("TID:0x%" PRIx64 " task status in server: %s", taskStatus->taskId,
-                 jobTaskStatusStr(taskStatus->status));
-
-    schReleaseJob(taskStatus->refId);
-  }
+  SCH_ERR_JRET(schProcessOnTaskStatusRsp(&rsp.epId, rsp.taskStatus));
 
 _return:
 
@@ -856,7 +845,8 @@ int32_t schMakeCallbackParam(SSchJob *pJob, SSchTask *pTask, void **pParam) {
   param->queryId = pJob->queryId;
   param->refId = pJob->refId;
   param->taskId = SCH_TASK_ID(pTask);
-  param->transport = pJob->pTrans;
+  param->pTrans = pJob->pTrans;
+  param->taskId = pTask->taskId;
 
   *pParam = param;
 
@@ -1158,7 +1148,7 @@ int32_t schBuildAndSendMsg(SSchJob *pJob, SSchTask *pTask, SQueryNodeAddr *addr,
                                (rpcCtx.args ? &rpcCtx : NULL)));
 
   if (msgType == TDMT_VND_QUERY) {
-    SCH_ERR_RET(schRecordTaskExecNode(pJob, pTask, addr, trans.pHandle));
+    SCH_ERR_RET(schAppendTaskExecNode(pJob, pTask, addr, pTask->execIdx));
   }
 
   return TSDB_CODE_SUCCESS;
diff --git a/source/libs/scheduler/src/scheduler.c b/source/libs/scheduler/src/scheduler.c
index 522bd8044d43709f9139092dd705ab123c7799ea..25d07aa35d11064490541c26def1130e5b51ed23 100644
--- a/source/libs/scheduler/src/scheduler.c
+++ b/source/libs/scheduler/src/scheduler.c
@@ -176,6 +176,10 @@ int32_t scheduleCancelJob(int64_t job) {
   SCH_RET(code);
 }
 
+void schedulerStopTransport(void *pTrans) {
+  // CLOSE && REMOVE RELATED HB CONNECTIONS
+}
+
 void schedulerFreeJob(int64_t job) {
   SSchJob *pJob = schAcquireJob(job);
   if (NULL == pJob) {