diff --git a/src/system/detail/inc/vnode.h b/src/system/detail/inc/vnode.h
index 6e366b9b7fbfb0f5b6ad4d9c64d520c358a85e39..4ac08484274ad1cfaacc027f9f7f484a98d1f8e9 100644
--- a/src/system/detail/inc/vnode.h
+++ b/src/system/detail/inc/vnode.h
@@ -213,18 +213,20 @@ typedef struct {
  * Only the QInfo.signature == QInfo, this structure can be released safely.
  */
 #define TSDB_QINFO_QUERY_FLAG 0x1
-#define TSDB_QINFO_RESET_SIG(x) atomic_store_64(&((x)->signature), (uint64_t)(x))
-#define TSDB_QINFO_SET_QUERY_FLAG(x) \
-  atomic_val_compare_exchange_64(&((x)->signature), (uint64_t)(x), TSDB_QINFO_QUERY_FLAG);
+//#define TSDB_QINFO_RESET_SIG(x) atomic_store_64(&((x)->signature), (uint64_t)(x))
+#define TSDB_QINFO_RESET_SIG(x)
+#define TSDB_QINFO_SET_QUERY_FLAG(x)
+//#define TSDB_QINFO_SET_QUERY_FLAG(x) \
+//  atomic_val_compare_exchange_64(&((x)->signature), (uint64_t)(x), TSDB_QINFO_QUERY_FLAG);
 
 // live lock: wait for query reaching a safe-point, release all resources
 // belongs to this query
 #define TSDB_WAIT_TO_SAFE_DROP_QINFO(x)                                                       \
-  {                                                                                           \
-    while (atomic_val_compare_exchange_64(&((x)->signature), (x), 0) == TSDB_QINFO_QUERY_FLAG) { \
-      taosMsleep(1);                                                                          \
-    }                                                                                         \
-  }
+//  {                                                                                           \
+//    while (atomic_val_compare_exchange_64(&((x)->signature), (x), 0) == TSDB_QINFO_QUERY_FLAG) { \
+//      taosMsleep(1);                                                                          \
+//    }                                                                                         \
+//  }
 
 struct tSQLBinaryExpr;
 
@@ -370,6 +372,8 @@ void vnodeFreeQInfo(void *, bool);
 void vnodeFreeQInfoInQueue(void *param);
 
 bool vnodeIsQInfoValid(void *param);
+void vnodeDecRefCount(void *param);
+void vnodeAddRefCount(void *param);
 
 int32_t vnodeConvertQueryMeterMsg(SQueryMeterMsg *pQuery);
 
diff --git a/src/system/detail/inc/vnodeRead.h b/src/system/detail/inc/vnodeRead.h
index d059075142126545a84c9cd60c0b14e1b79c5d7a..3a1b6f7949e398eb547c3c6bfec79bc82869e1fb 100644
--- a/src/system/detail/inc/vnodeRead.h
+++ b/src/system/detail/inc/vnodeRead.h
@@ -52,7 +52,7 @@ typedef struct SQueryLoadCompBlockInfo {
  * the header file info for one vnode
  */
 typedef struct SHeaderFileInfo {
-  int32_t fileID;        // file id
+  int32_t fileID;  // file id
 } SHeaderFileInfo;
 
 typedef struct SQueryCostSummary {
@@ -99,17 +99,17 @@ typedef struct SQueryFilesInfo {
   uint32_t         numOfFiles;  // the total available number of files for this virtual node during query execution
   int32_t          current;     // the memory mapped header file, NOTE: only one header file can be mmap.
   int32_t          vnodeId;
-  
-  int32_t          headerFd;    // header file fd
-  char*            pHeaderFileData; // mmap header files
-  int64_t          headFileSize;
-  int32_t          dataFd;
-  int32_t          lastFd;
-  
-  char             headerFilePath[PATH_MAX];  // current opened header file name
-  char             dataFilePath[PATH_MAX];    // current opened data file name
-  char             lastFilePath[PATH_MAX];    // current opened last file path
-  char             dbFilePathPrefix[PATH_MAX];
+
+  int32_t headerFd;         // header file fd
+  char*   pHeaderFileData;  // mmap header files
+  int64_t headFileSize;
+  int32_t dataFd;
+  int32_t lastFd;
+
+  char headerFilePath[PATH_MAX];  // current opened header file name
+  char dataFilePath[PATH_MAX];    // current opened data file name
+  char lastFilePath[PATH_MAX];    // current opened last file path
+  char dbFilePathPrefix[PATH_MAX];
 } SQueryFilesInfo;
 
 typedef struct RuntimeEnvironment {
@@ -129,17 +129,17 @@ typedef struct RuntimeEnvironment {
   SQueryLoadBlockInfo loadBlockInfo;         /* record current block load information */
   SQueryLoadCompBlockInfo loadCompBlockInfo; /* record current compblock information in SQuery */
   SQueryFilesInfo         vnodeFileInfo;
-  int16_t            numOfRowsPerPage;
-  int16_t            offset[TSDB_MAX_COLUMNS];
-  int16_t            scanFlag;  // denotes reversed scan of data or not
-  SInterpolationInfo interpoInfo;
-  SData**            pInterpoBuf;
-  SOutputRes*        pResult;  // reference to SQuerySupporter->pResult
-  void*              hashList;
-  int32_t            usedIndex;  // assigned SOutputRes in list
-  STSBuf*            pTSBuf;
-  STSCursor          cur;
-  SQueryCostSummary  summary;
+  int16_t                 numOfRowsPerPage;
+  int16_t                 offset[TSDB_MAX_COLUMNS];
+  int16_t                 scanFlag;  // denotes reversed scan of data or not
+  SInterpolationInfo      interpoInfo;
+  SData**                 pInterpoBuf;
+  SOutputRes*             pResult;  // reference to SQuerySupporter->pResult
+  void*                   hashList;
+  int32_t                 usedIndex;  // assigned SOutputRes in list
+  STSBuf*                 pTSBuf;
+  STSCursor               cur;
+  SQueryCostSummary       summary;
 } SQueryRuntimeEnv;
 
 /* intermediate result during multimeter query involves interval */
@@ -214,14 +214,12 @@ typedef struct SMeterQuerySupportObj {
 
   SMeterDataInfo* pMeterDataInfo;
 
-  TSKEY*  tsList;
-  int32_t tsNum;
-
+  TSKEY* tsList;
 } SMeterQuerySupportObj;
 
 typedef struct _qinfo {
-  uint64_t signature;
-
+  uint64_t       signature;
+  int32_t        refCount;  // QInfo reference count, when the value is 0, it can be released safely
   char           user[TSDB_METER_ID_LEN + 1];
   char           sql[TSDB_SHOW_SQL_LEN];
   uint8_t        stream;
@@ -231,24 +229,21 @@ typedef struct _qinfo {
   int64_t        useconds;
   int            killed;
   struct _qinfo *prev, *next;
+  SQuery         query;
+  int            num;
+  int            totalPoints;
+  int            pointsRead;
+  int            pointsReturned;
+  int            pointsInterpo;
+  int            code;
+  char           bufIndex;
+  char           changed;
+  char           over;
+  SMeterObj*     pObj;
+  sem_t          dataReady;
 
-  SQuery     query;
-  int        num;
-  int        totalPoints;
-  int        pointsRead;
-  int        pointsReturned;
-  int        pointsInterpo;
-  int        code;
-  char       bufIndex;
-  char       changed;
-  char       over;
-  SMeterObj* pObj;
-
-  int (*fp)(SMeterObj*, SQuery*);
-
-  sem_t                  dataReady;
   SMeterQuerySupportObj* pMeterQuerySupporter;
-
+  int (*fp)(SMeterObj*, SQuery*);
 } SQInfo;
 
 int32_t vnodeQuerySingleMeterPrepare(SQInfo* pQInfo, SMeterObj* pMeterObj, SMeterQuerySupportObj* pSMultiMeterObj,
diff --git a/src/system/detail/src/vnodeQueryProcess.c b/src/system/detail/src/vnodeQueryProcess.c
index 6fa0891baa4f49cf5e5cb3ad74095aabd94bc94e..f39ca0dea1c63821f0cca023a4b9e77a23f64462 100644
--- a/src/system/detail/src/vnodeQueryProcess.c
+++ b/src/system/detail/src/vnodeQueryProcess.c
@@ -890,12 +890,16 @@ static void vnodeMultiMeterQueryProcessor(SQInfo *pQInfo) {
 
     dTrace("QInfo:%p points returned:%d, totalRead:%d totalReturn:%d", pQInfo, pQuery->pointsRead, pQInfo->pointsRead,
            pQInfo->pointsReturned);
+    
+    vnodeDecRefCount(pQInfo);
     return;
   }
 
   pSupporter->pMeterDataInfo = (SMeterDataInfo *)calloc(1, sizeof(SMeterDataInfo) * pSupporter->numOfMeters);
   if (pSupporter->pMeterDataInfo == NULL) {
     dError("QInfo:%p failed to allocate memory, %s", pQInfo, strerror(errno));
+    pQInfo->code = -TSDB_CODE_SERV_OUT_OF_MEMORY;
+    vnodeDecRefCount(pQInfo);
     return;
   }
 
@@ -912,6 +916,7 @@ static void vnodeMultiMeterQueryProcessor(SQInfo *pQInfo) {
   // failed to save all intermediate results into disk, abort further query processing
   if (doCloseAllOpenedResults(pSupporter) != TSDB_CODE_SUCCESS) {
     dError("QInfo:%p failed to save intermediate results, abort further query processing", pQInfo);
+    vnodeDecRefCount(pQInfo);
     return;
   }
   
@@ -919,6 +924,7 @@ static void vnodeMultiMeterQueryProcessor(SQInfo *pQInfo) {
 
   if (isQueryKilled(pQuery)) {
     dTrace("QInfo:%p query killed, abort", pQInfo);
+    vnodeDecRefCount(pQInfo);
     return;
   }
 
@@ -940,6 +946,7 @@ static void vnodeMultiMeterQueryProcessor(SQInfo *pQInfo) {
   pQInfo->pointsRead += pQuery->pointsRead;
   dTrace("QInfo:%p points returned:%d, totalRead:%d totalReturn:%d", pQInfo, pQuery->pointsRead, pQInfo->pointsRead,
          pQInfo->pointsReturned);
+  vnodeDecRefCount(pQInfo);
 }
 
 /*
@@ -1174,10 +1181,13 @@ void vnodeSingleMeterQuery(SSchedMsg *pMsg) {
   if (pQInfo->killed) {
     TSDB_QINFO_RESET_SIG(pQInfo);
     dTrace("QInfo:%p it is already killed, reset signature and abort", pQInfo);
+    vnodeDecRefCount(pQInfo);
+  
     return;
   }
 
-  assert(pQInfo->signature == TSDB_QINFO_QUERY_FLAG);
+  assert(pQInfo->refCount >= 1);
+//  assert(pQInfo->signature == TSDB_QINFO_QUERY_FLAG);
 
   SQuery *   pQuery = &pQInfo->query;
   SMeterObj *pMeterObj = pQInfo->pObj;
@@ -1215,6 +1225,7 @@ void vnodeSingleMeterQuery(SSchedMsg *pMsg) {
 
     sem_post(&pQInfo->dataReady);
     TSDB_QINFO_RESET_SIG(pQInfo);
+    vnodeDecRefCount(pQInfo);
 
     return;
   }
@@ -1237,6 +1248,8 @@ void vnodeSingleMeterQuery(SSchedMsg *pMsg) {
 
           sem_post(&pQInfo->dataReady);
           TSDB_QINFO_RESET_SIG(pQInfo);
+          vnodeDecRefCount(pQInfo);
+  
           return;
         }
       }
@@ -1249,7 +1262,7 @@ void vnodeSingleMeterQuery(SSchedMsg *pMsg) {
     vnodePrintQueryStatistics(pQInfo->pMeterQuerySupporter);
     sem_post(&pQInfo->dataReady);
     TSDB_QINFO_RESET_SIG(pQInfo);
-
+    vnodeDecRefCount(pQInfo);
     return;
   }
 
@@ -1284,8 +1297,10 @@ void vnodeSingleMeterQuery(SSchedMsg *pMsg) {
            pQInfo, pMeterObj->vnode, pMeterObj->sid, pMeterObj->meterId, pQuery->pointsRead);
   }
 
-  sem_post(&pQInfo->dataReady);
   TSDB_QINFO_RESET_SIG(pQInfo);
+  sem_post(&pQInfo->dataReady);
+  
+  vnodeDecRefCount(pQInfo);
 }
 
 void vnodeMultiMeterQuery(SSchedMsg *pMsg) {
@@ -1297,11 +1312,13 @@ void vnodeMultiMeterQuery(SSchedMsg *pMsg) {
 
   if (pQInfo->killed) {
     TSDB_QINFO_RESET_SIG(pQInfo);
+    vnodeDecRefCount(pQInfo);
     dTrace("QInfo:%p it is already killed, reset signature and abort", pQInfo);
     return;
   }
 
-  assert(pQInfo->signature == TSDB_QINFO_QUERY_FLAG);
+  assert(pQInfo->refCount >= 1);
+//  assert(pQInfo->signature == TSDB_QINFO_QUERY_FLAG);
 
   SQuery *pQuery = &pQInfo->query;
   pQuery->pointsRead = 0;
@@ -1337,4 +1354,5 @@ void vnodeMultiMeterQuery(SSchedMsg *pMsg) {
 
   sem_post(&pQInfo->dataReady);
   TSDB_QINFO_RESET_SIG(pQInfo);
+  vnodeDecRefCount(pQInfo);
 }
diff --git a/src/system/detail/src/vnodeRead.c b/src/system/detail/src/vnodeRead.c
index 21e83c5198decf552d2a30fed486465f4a4402d2..2ea41d9d58cad91d8b19fa48a0904b9bb1365a77 100644
--- a/src/system/detail/src/vnodeRead.c
+++ b/src/system/detail/src/vnodeRead.c
@@ -392,10 +392,10 @@ __clean_memory:
   return NULL;
 }
 
-static void vnodeFreeQInfoInQueueImpl(SSchedMsg *pMsg) {
-  SQInfo *pQInfo = (SQInfo *)pMsg->ahandle;
-  vnodeFreeQInfo(pQInfo, true);
-}
+//static void vnodeFreeQInfoInQueueImpl(SSchedMsg *pMsg) {
+//  SQInfo *pQInfo = (SQInfo *)pMsg->ahandle;
+//  vnodeFreeQInfo(pQInfo, true);
+//}
 
 void vnodeFreeQInfoInQueue(void *param) {
   SQInfo *pQInfo = (SQInfo *)param;
@@ -403,15 +403,18 @@ void vnodeFreeQInfoInQueue(void *param) {
   if (!vnodeIsQInfoValid(pQInfo)) return;
 
   pQInfo->killed = 1;
-
-  dTrace("QInfo:%p set kill flag and add to queue, stop query ASAP", pQInfo);
-  SSchedMsg schedMsg = {0};
-  schedMsg.fp = vnodeFreeQInfoInQueueImpl;
-
-  schedMsg.msg = NULL;
-  schedMsg.thandle = (void *)1;
-  schedMsg.ahandle = param;
-  taosScheduleTask(queryQhandle, &schedMsg);
+  dTrace("QInfo:%p set kill flag to free QInfo");
+  
+  vnodeDecRefCount(pQInfo);
+  
+//  dTrace("QInfo:%p set kill flag and add to queue, stop query ASAP", pQInfo);
+//  SSchedMsg schedMsg = {0};
+//  schedMsg.fp = vnodeFreeQInfoInQueueImpl;
+
+//  schedMsg.msg = NULL;
+//  schedMsg.thandle = (void *)1;
+//  schedMsg.ahandle = param;
+//  taosScheduleTask(queryQhandle, &schedMsg);
 }
 
 void vnodeFreeQInfo(void *param, bool decQueryRef) {
@@ -499,7 +502,30 @@ bool vnodeIsQInfoValid(void *param) {
    * into local variable, then compare by using local variable
    */
   uint64_t sig = pQInfo->signature;
-  return (sig == (uint64_t)pQInfo) || (sig == TSDB_QINFO_QUERY_FLAG);
+//  return (sig == (uint64_t)pQInfo) || (sig == TSDB_QINFO_QUERY_FLAG);
+  return (sig == (uint64_t)pQInfo);
+}
+
+void vnodeDecRefCount(void *param) {
+  SQInfo *pQInfo = (SQInfo*) param;
+  
+  assert(vnodeIsQInfoValid(pQInfo));
+  
+  int32_t ref = atomic_sub_fetch_32(&pQInfo->refCount, 1);
+  dTrace("QInfo:%p decrease obj refcount, %d", pQInfo, ref);
+  
+  if (ref == 0) {
+    vnodeFreeQInfo(pQInfo, true);
+  }
+}
+
+void vnodeAddRefCount(void *param) {
+  SQInfo *pQInfo = (SQInfo*) param;
+  
+  assert(vnodeIsQInfoValid(pQInfo));
+  
+  int32_t ref = atomic_add_fetch_32(&pQInfo->refCount, 1);
+  dTrace("QInfo:%p add refcount, %d", pQInfo, ref);
 }
 
 void vnodeQueryData(SSchedMsg *pMsg) {
@@ -511,10 +537,11 @@ void vnodeQueryData(SSchedMsg *pMsg) {
   if (pQInfo->killed) {
     TSDB_QINFO_RESET_SIG(pQInfo);
     dTrace("QInfo:%p it is already killed, reset signature and abort", pQInfo);
+    vnodeDecRefCount(pQInfo);
     return;
   }
 
-  assert(pQInfo->signature == TSDB_QINFO_QUERY_FLAG);
+//  assert(pQInfo->signature == TSDB_QINFO_QUERY_FLAG);
   pQuery = &(pQInfo->query);
 
   SMeterObj *pObj = pQInfo->pObj;
@@ -586,6 +613,7 @@ void vnodeQueryData(SSchedMsg *pMsg) {
   dTrace("QInfo:%p reset signature", pQInfo);
   TSDB_QINFO_RESET_SIG(pQInfo);
   sem_post(&pQInfo->dataReady);
+  vnodeDecRefCount(pQInfo);
 }
 
 void *vnodeQueryInTimeRange(SMeterObj **pMetersObj, SSqlGroupbyExpr *pGroupbyExpr, SSqlFunctionExpr *pSqlExprs,
@@ -668,14 +696,22 @@ void *vnodeQueryInTimeRange(SMeterObj **pMetersObj, SSqlGroupbyExpr *pGroupbyExp
   }
 
   // set in query flag
-  pQInfo->signature = TSDB_QINFO_QUERY_FLAG;
-
+//  pQInfo->signature = TSDB_QINFO_QUERY_FLAG;
+  
+  /*
+   * The reference count, which is 2, is for both the current query thread and the future retrieve request,
+   * which will always be issued by client to acquire data or free SQInfo struct.
+   */
+  vnodeAddRefCount(pQInfo);
+  vnodeAddRefCount(pQInfo);
+  
   schedMsg.msg = NULL;
   schedMsg.thandle = (void *)1;
   schedMsg.ahandle = pQInfo;
 
-  dTrace("QInfo:%p set query flag and prepare runtime environment completed, wait for schedule", pQInfo);
-
+  dTrace("QInfo:%p set query flag and prepare runtime environment completed, ref:%d, wait for schedule", pQInfo,
+      pQInfo->refCount);
+  
   taosScheduleTask(queryQhandle, &schedMsg);
   return pQInfo;
 
@@ -779,8 +815,10 @@ void *vnodeQueryOnMultiMeters(SMeterObj **pMetersObj, SSqlGroupbyExpr *pGroupbyE
     return pQInfo;
   }
 
-  pQInfo->signature = TSDB_QINFO_QUERY_FLAG;
-
+//  pQInfo->signature = TSDB_QINFO_QUERY_FLAG;
+  vnodeAddRefCount(pQInfo);
+  vnodeAddRefCount(pQInfo);
+  
   schedMsg.msg = NULL;
   schedMsg.thandle = (void *)1;
   schedMsg.ahandle = pQInfo;
@@ -862,19 +900,22 @@ int vnodeSaveQueryResult(void *handle, char *data, int32_t *size) {
   if (pQInfo->over == 0) {
     //dTrace("QInfo:%p set query flag, oldSig:%p, func:%s", pQInfo, pQInfo->signature, __FUNCTION__);
     dTrace("QInfo:%p set query flag, oldSig:%p", pQInfo, pQInfo->signature);
-    uint64_t oldSignature = TSDB_QINFO_SET_QUERY_FLAG(pQInfo);
+//    uint64_t oldSignature = TSDB_QINFO_SET_QUERY_FLAG(pQInfo);
 
     /*
      * If SQInfo has been released, the value of signature cannot be equalled to the address of pQInfo,
      * since in release function, the original value has been destroyed. However, this memory area may be reused
      * by another function. It may be 0 or any value, but it is rarely still be equalled to the address of SQInfo.
      */
-    if (oldSignature == 0 || oldSignature != (uint64_t)pQInfo) {
-      dTrace("%p freed or killed, old sig:%p abort query", pQInfo, oldSignature);
+//    if (oldSignature == 0 || oldSignature != (uint64_t)pQInfo) {
+    if (pQInfo->killed == 1) {
+//      dTrace("%p freed or killed, old sig:%p abort query", pQInfo, oldSignature);
+      dTrace("%p freed or killed, abort query", pQInfo);
     } else {
+      vnodeAddRefCount(pQInfo);
       dTrace("%p add query into task queue for schedule", pQInfo);
-
-      SSchedMsg schedMsg;
+      
+      SSchedMsg schedMsg = {0};
 
       if (pQInfo->pMeterQuerySupporter != NULL) {
         if (pQInfo->pMeterQuerySupporter->pSidSet == NULL) {
diff --git a/src/system/detail/src/vnodeShell.c b/src/system/detail/src/vnodeShell.c
index cfdd9567683a55508bb32cc7a0ea208ccbddbe66..6ff3f4d27ca3e238574eaefcd7751f8e0ce71726 100644
--- a/src/system/detail/src/vnodeShell.c
+++ b/src/system/detail/src/vnodeShell.c
@@ -470,9 +470,11 @@ void vnodeExecuteRetrieveReq(SSchedMsg *pSched) {
   pMsg += size;
   msgLen = pMsg - pStart;
 
+  assert(code != TSDB_CODE_ACTION_IN_PROGRESS);
+  
   if (numOfRows == 0 && (pRetrieve->qhandle == (uint64_t)pObj->qhandle) && (code != TSDB_CODE_ACTION_IN_PROGRESS)) {
     dTrace("QInfo:%p %s free qhandle code:%d", pObj->qhandle, __FUNCTION__, code);
-    vnodeFreeQInfo(pObj->qhandle, true);
+    vnodeDecRefCount(pObj->qhandle);
     pObj->qhandle = NULL;
   }