diff --git a/include/util/taoserror.h b/include/util/taoserror.h
index 59bba315f4..52d8a75ee0 100644
--- a/include/util/taoserror.h
+++ b/include/util/taoserror.h
@@ -415,6 +415,7 @@ int32_t* taosGetErrno();
 #define TSDB_CODE_VND_NO_AVAIL_BUFPOOL          TAOS_DEF_ERROR_CODE(0, 0x0528)
 #define TSDB_CODE_VND_STOPPED                   TAOS_DEF_ERROR_CODE(0, 0x0529)
 #define TSDB_CODE_VND_DUP_REQUEST               TAOS_DEF_ERROR_CODE(0, 0x0530)
+#define TSDB_CODE_VND_QUERY_BUSY                TAOS_DEF_ERROR_CODE(0, 0x0531)
 
 // tsdb
 #define TSDB_CODE_TDB_INVALID_TABLE_ID          TAOS_DEF_ERROR_CODE(0, 0x0600)
diff --git a/source/dnode/vnode/src/inc/tsdb.h b/source/dnode/vnode/src/inc/tsdb.h
index a58301adf2..8c8775548d 100644
--- a/source/dnode/vnode/src/inc/tsdb.h
+++ b/source/dnode/vnode/src/inc/tsdb.h
@@ -65,7 +65,6 @@ typedef struct SSmaInfo         SSmaInfo;
 typedef struct SBlockCol        SBlockCol;
 typedef struct SVersionRange    SVersionRange;
 typedef struct SLDataIter       SLDataIter;
-typedef struct SQueryNode       SQueryNode;
 typedef struct SDiskCol         SDiskCol;
 typedef struct SDiskData        SDiskData;
 typedef struct SDiskDataBuilder SDiskDataBuilder;
@@ -209,13 +208,11 @@ int32_t tsdbDecmprColData(uint8_t *pIn, SBlockCol *pBlockCol, int8_t cmprAlg, in
                           uint8_t **ppBuf);
 // tsdbMemTable ==============================================================================================
 // SMemTable
-typedef int32_t (*_tsdb_reseek_func_t)(void *pQHandle);
-
 int32_t  tsdbMemTableCreate(STsdb *pTsdb, SMemTable **ppMemTable);
-void     tsdbMemTableDestroy(SMemTable *pMemTable);
+void     tsdbMemTableDestroy(SMemTable *pMemTable, bool proactive);
 STbData *tsdbGetTbDataFromMemTable(SMemTable *pMemTable, tb_uid_t suid, tb_uid_t uid);
-int32_t  tsdbRefMemTable(SMemTable *pMemTable, void *pQHandle, _tsdb_reseek_func_t reseek, SQueryNode **ppNode);
-int32_t  tsdbUnrefMemTable(SMemTable *pMemTable, SQueryNode *pNode);
+int32_t  tsdbRefMemTable(SMemTable *pMemTable, SQueryNode *pQNode);
+int32_t  tsdbUnrefMemTable(SMemTable *pMemTable, SQueryNode *pNode, bool proactive);
 SArray  *tsdbMemTableGetTbDataArray(SMemTable *pMemTable);
 // STbDataIter
 int32_t tsdbTbDataIterCreate(STbData *pTbData, TSDBKEY *pFrom, int8_t backward, STbDataIter **ppIter);
@@ -293,8 +290,8 @@ int32_t tsdbDelFReaderClose(SDelFReader **ppReader);
 int32_t tsdbReadDelData(SDelFReader *pReader, SDelIdx *pDelIdx, SArray *aDelData);
 int32_t tsdbReadDelIdx(SDelFReader *pReader, SArray *aDelIdx);
 // tsdbRead.c ==============================================================================================
-int32_t tsdbTakeReadSnap(STsdbReader *pReader, _tsdb_reseek_func_t reseek, STsdbReadSnap **ppSnap);
-void    tsdbUntakeReadSnap(STsdbReader *pReader, STsdbReadSnap *pSnap);
+int32_t tsdbTakeReadSnap(STsdbReader *pReader, _query_reseek_func_t reseek, STsdbReadSnap **ppSnap);
+void    tsdbUntakeReadSnap(STsdbReader *pReader, STsdbReadSnap *pSnap, bool proactive);
 // tsdbMerge.c ==============================================================================================
 int32_t tsdbMerge(STsdb *pTsdb);
 
@@ -369,13 +366,6 @@ struct STbData {
   STbData     *next;
 };
 
-struct SQueryNode {
-  SQueryNode         *pNext;
-  SQueryNode        **ppNext;
-  void               *pQHandle;
-  _tsdb_reseek_func_t reseek;
-};
-
 struct SMemTable {
   SRWLatch         latch;
   STsdb           *pTsdb;
@@ -392,7 +382,6 @@ struct SMemTable {
     int32_t   nBucket;
     STbData **aBucket;
   };
-  SQueryNode qList;
 };
 
 struct TSDBROW {
diff --git a/source/dnode/vnode/src/inc/vnd.h b/source/dnode/vnode/src/inc/vnd.h
index e075d8a6ca..e0d0e9408b 100644
--- a/source/dnode/vnode/src/inc/vnd.h
+++ b/source/dnode/vnode/src/inc/vnd.h
@@ -61,10 +61,19 @@ struct SVBufPoolNode {
 };
 
 struct SVBufPool {
-  SVBufPool*        next;
+  SVBufPool* freeNext;
+  SVBufPool* recycleNext;
+  SVBufPool* recyclePrev;
+
+  // query handle list
+  TdThreadMutex mutex;
+  int32_t       nQuery;
+  SQueryNode    qList;
+
   SVnode*           pVnode;
-  TdThreadSpinlock* lock;
+  int32_t           id;
   volatile int32_t  nRef;
+  TdThreadSpinlock* lock;
   int64_t           size;
   uint8_t*          ptr;
   SVBufPoolNode*    pTail;
@@ -74,6 +83,8 @@ struct SVBufPool {
 int32_t vnodeOpenBufPool(SVnode* pVnode);
 int32_t vnodeCloseBufPool(SVnode* pVnode);
 void    vnodeBufPoolReset(SVBufPool* pPool);
+void    vnodeBufPoolAddToFreeList(SVBufPool* pPool);
+int32_t vnodeBufPoolRecycle(SVBufPool* pPool);
 
 // vnodeQuery.c
 int32_t vnodeQueryOpen(SVnode* pVnode);
diff --git a/source/dnode/vnode/src/inc/vnodeInt.h b/source/dnode/vnode/src/inc/vnodeInt.h
index 81873a38bc..9c5f47b731 100644
--- a/source/dnode/vnode/src/inc/vnodeInt.h
+++ b/source/dnode/vnode/src/inc/vnodeInt.h
@@ -76,6 +76,7 @@ typedef struct SRSmaSnapReader    SRSmaSnapReader;
 typedef struct SRSmaSnapWriter    SRSmaSnapWriter;
 typedef struct SSnapDataHdr       SSnapDataHdr;
 typedef struct SCommitInfo        SCommitInfo;
+typedef struct SQueryNode         SQueryNode;
 
 #define VNODE_META_DIR  "meta"
 #define VNODE_TSDB_DIR  "tsdb"
@@ -87,17 +88,29 @@ typedef struct SCommitInfo        SCommitInfo;
 #define VNODE_RSMA1_DIR "rsma1"
 #define VNODE_RSMA2_DIR "rsma2"
 
+#define VNODE_BUFPOOL_SEGMENTS 3
+
 #define VND_INFO_FNAME "vnode.json"
 
 // vnd.h
+typedef int32_t (*_query_reseek_func_t)(void* pQHandle);
+struct SQueryNode {
+  SQueryNode*          pNext;
+  SQueryNode**         ppNext;
+  void*                pQHandle;
+  _query_reseek_func_t reseek;
+};
 
 void* vnodeBufPoolMalloc(SVBufPool* pPool, int size);
 void* vnodeBufPoolMallocAligned(SVBufPool* pPool, int size);
 void  vnodeBufPoolFree(SVBufPool* pPool, void* p);
 void  vnodeBufPoolRef(SVBufPool* pPool);
-void  vnodeBufPoolUnRef(SVBufPool* pPool);
+void  vnodeBufPoolUnRef(SVBufPool* pPool, bool proactive);
 int   vnodeDecodeInfo(uint8_t* pData, SVnodeInfo* pInfo);
 
+int32_t vnodeBufPoolRegisterQuery(SVBufPool* pPool, SQueryNode* pQNode);
+void    vnodeBufPoolDeregisterQuery(SVBufPool* pPool, SQueryNode* pQNode, bool proactive);
+
 // meta
 typedef struct SMCtbCursor SMCtbCursor;
 typedef struct SMStbCursor SMStbCursor;
@@ -331,16 +344,24 @@ typedef struct SVCommitSched {
 } SVCommitSched;
 
 struct SVnode {
-  char*         path;
-  SVnodeCfg     config;
-  SVState       state;
-  SVStatis      statis;
-  STfs*         pTfs;
-  SMsgCb        msgCb;
+  char*     path;
+  SVnodeCfg config;
+  SVState   state;
+  SVStatis  statis;
+  STfs*     pTfs;
+  SMsgCb    msgCb;
+
+  // Buffer Pool
   TdThreadMutex mutex;
   TdThreadCond  poolNotEmpty;
-  SVBufPool*    pPool;
+  SVBufPool*    aBufPool[VNODE_BUFPOOL_SEGMENTS];
+  SVBufPool*    freeList;
   SVBufPool*    inUse;
+  SVBufPool*    onCommit;
+  SVBufPool*    recycleHead;
+  SVBufPool*    recycleTail;
+  SVBufPool*    onRecycle;
+
   SMeta*        pMeta;
   SSma*         pSma;
   STsdb*        pTsdb;
diff --git a/source/dnode/vnode/src/tsdb/tsdbCacheRead.c b/source/dnode/vnode/src/tsdb/tsdbCacheRead.c
index 1c1626ba5c..6a5acecfc3 100644
--- a/source/dnode/vnode/src/tsdb/tsdbCacheRead.c
+++ b/source/dnode/vnode/src/tsdb/tsdbCacheRead.c
@@ -208,13 +208,21 @@ static int32_t tsdbCacheQueryReseek(void* pQHandle) {
   int32_t           code = 0;
   SCacheRowsReader* pReader = pQHandle;
 
-  taosThreadMutexLock(&pReader->readerMutex);
+  code = taosThreadMutexTryLock(&pReader->readerMutex);
+  if (code == 0) {
+    // pause current reader's state if not paused, save ts & version for resuming
+    // just wait for the big all tables' snapshot untaking for now
 
-  // pause current reader's state if not paused, save ts & version for resuming
-  // just wait for the big all tables' snapshot untaking for now
+    code = TSDB_CODE_VND_QUERY_BUSY;
 
-  taosThreadMutexUnlock(&pReader->readerMutex);
-  return code;
+    taosThreadMutexUnlock(&pReader->readerMutex);
+
+    return code;
+  } else if (code == EBUSY) {
+    return TSDB_CODE_VND_QUERY_BUSY;
+  } else {
+    return -1;
+  }
 }
 
 int32_t tsdbRetrieveCacheRows(void* pReader, SSDataBlock* pResBlock, const int32_t* slotIds, SArray* pTableUidList) {
@@ -375,7 +383,7 @@ _end:
   tsdbDataFReaderClose(&pr->pDataFReader);
 
   resetLastBlockLoadInfo(pr->pLoadInfo);
-  tsdbUntakeReadSnap((STsdbReader*)pr, pr->pReadSnap);
+  tsdbUntakeReadSnap((STsdbReader*)pr, pr->pReadSnap, true);
   taosThreadMutexUnlock(&pr->readerMutex);
 
   for (int32_t j = 0; j < pr->numOfCols; ++j) {
diff --git a/source/dnode/vnode/src/tsdb/tsdbCommit.c b/source/dnode/vnode/src/tsdb/tsdbCommit.c
index 31d6fd85c6..d15f848cfd 100644
--- a/source/dnode/vnode/src/tsdb/tsdbCommit.c
+++ b/source/dnode/vnode/src/tsdb/tsdbCommit.c
@@ -175,7 +175,7 @@ int32_t tsdbCommit(STsdb *pTsdb, SCommitInfo *pInfo) {
     pTsdb->imem = NULL;
     taosThreadRwlockUnlock(&pTsdb->rwLock);
 
-    tsdbUnrefMemTable(pMemTable, NULL);
+    tsdbUnrefMemTable(pMemTable, NULL, true);
     goto _exit;
   }
 
@@ -1664,7 +1664,7 @@ int32_t tsdbFinishCommit(STsdb *pTsdb) {
   // unlock
   taosThreadRwlockUnlock(&pTsdb->rwLock);
   if (pMemTable) {
-    tsdbUnrefMemTable(pMemTable, NULL);
+    tsdbUnrefMemTable(pMemTable, NULL, true);
   }
 
 _exit:
diff --git a/source/dnode/vnode/src/tsdb/tsdbMemTable.c b/source/dnode/vnode/src/tsdb/tsdbMemTable.c
index 6bbaa31ed3..d68afbed1f 100644
--- a/source/dnode/vnode/src/tsdb/tsdbMemTable.c
+++ b/source/dnode/vnode/src/tsdb/tsdbMemTable.c
@@ -64,8 +64,8 @@ int32_t tsdbMemTableCreate(STsdb *pTsdb, SMemTable **ppMemTable) {
     taosMemoryFree(pMemTable);
     goto _err;
   }
-  pMemTable->qList.pNext = &pMemTable->qList;
-  pMemTable->qList.ppNext = &pMemTable->qList.pNext;
+  // pMemTable->qList.pNext = &pMemTable->qList;
+  // pMemTable->qList.ppNext = &pMemTable->qList.pNext;
   vnodeBufPoolRef(pMemTable->pPool);
 
   *ppMemTable = pMemTable;
@@ -76,9 +76,9 @@ _err:
   return code;
 }
 
-void tsdbMemTableDestroy(SMemTable *pMemTable) {
+void tsdbMemTableDestroy(SMemTable *pMemTable, bool proactive) {
   if (pMemTable) {
-    vnodeBufPoolUnRef(pMemTable->pPool);
+    vnodeBufPoolUnRef(pMemTable->pPool, proactive);
     taosMemoryFree(pMemTable->aBucket);
     taosMemoryFree(pMemTable);
   }
@@ -749,42 +749,27 @@ _exit:
 
 int32_t tsdbGetNRowsInTbData(STbData *pTbData) { return pTbData->sl.size; }
 
-int32_t tsdbRefMemTable(SMemTable *pMemTable, void *pQHandle, _tsdb_reseek_func_t reseek, SQueryNode **ppNode) {
+int32_t tsdbRefMemTable(SMemTable *pMemTable, SQueryNode *pQNode) {
   int32_t code = 0;
 
   int32_t nRef = atomic_fetch_add_32(&pMemTable->nRef, 1);
   ASSERT(nRef > 0);
-  /*
-  // register handle (todo: take concurrency in consideration)
-  *ppNode = taosMemoryMalloc(sizeof(SQueryNode));
-  if (*ppNode == NULL) {
-    code = TSDB_CODE_OUT_OF_MEMORY;
-    goto _exit;
-  }
-  (*ppNode)->pQHandle = pQHandle;
-  (*ppNode)->reseek = reseek;
-  (*ppNode)->pNext = pMemTable->qList.pNext;
-  (*ppNode)->ppNext = &pMemTable->qList.pNext;
-  pMemTable->qList.pNext->ppNext = &(*ppNode)->pNext;
-  pMemTable->qList.pNext = *ppNode;
-  */
+
+  vnodeBufPoolRegisterQuery(pMemTable->pPool, pQNode);
+
 _exit:
   return code;
 }
 
-int32_t tsdbUnrefMemTable(SMemTable *pMemTable, SQueryNode *pNode) {
+int32_t tsdbUnrefMemTable(SMemTable *pMemTable, SQueryNode *pNode, bool proactive) {
   int32_t code = 0;
-  /*
-  // unregister handle (todo: take concurrency in consideration)
+
   if (pNode) {
-    pNode->pNext->ppNext = pNode->ppNext;
-    *pNode->ppNext = pNode->pNext;
-    taosMemoryFree(pNode);
+    vnodeBufPoolDeregisterQuery(pMemTable->pPool, pNode, proactive);
   }
-  */
-  int32_t nRef = atomic_sub_fetch_32(&pMemTable->nRef, 1);
-  if (nRef == 0) {
-    tsdbMemTableDestroy(pMemTable);
+
+  if (atomic_sub_fetch_32(&pMemTable->nRef, 1) == 0) {
+    tsdbMemTableDestroy(pMemTable, proactive);
   }
 
   return code;
@@ -828,28 +813,28 @@ _exit:
   return aTbDataP;
 }
 
-int32_t tsdbRecycleMemTable(SMemTable *pMemTable) {
-  int32_t code = 0;
+// int32_t tsdbRecycleMemTable(SMemTable *pMemTable) {
+//   int32_t code = 0;
 
-  SQueryNode *pNode = pMemTable->qList.pNext;
-  while (1) {
-    ASSERT(pNode != &pMemTable->qList);
-    SQueryNode *pNextNode = pNode->pNext;
+//   SQueryNode *pNode = pMemTable->qList.pNext;
+//   while (1) {
+//     ASSERT(pNode != &pMemTable->qList);
+//     SQueryNode *pNextNode = pNode->pNext;
 
-    if (pNextNode == &pMemTable->qList) {
-      code = (*pNode->reseek)(pNode->pQHandle);
-      if (code) goto _exit;
-      break;
-    } else {
-      code = (*pNode->reseek)(pNode->pQHandle);
-      if (code) goto _exit;
-      pNode = pMemTable->qList.pNext;
-      ASSERT(pNode == pNextNode);
-    }
-  }
+//     if (pNextNode == &pMemTable->qList) {
+//       code = (*pNode->reseek)(pNode->pQHandle);
+//       if (code) goto _exit;
+//       break;
+//     } else {
+//       code = (*pNode->reseek)(pNode->pQHandle);
+//       if (code) goto _exit;
+//       pNode = pMemTable->qList.pNext;
+//       ASSERT(pNode == pNextNode);
+//     }
+//   }
 
-  // NOTE: Take care here, pMemTable is destroyed
+//   // NOTE: Take care here, pMemTable is destroyed
 
-_exit:
-  return code;
-}
+// _exit:
+//   return code;
+// }
diff --git a/source/dnode/vnode/src/tsdb/tsdbOpen.c b/source/dnode/vnode/src/tsdb/tsdbOpen.c
index f71b5b6706..8901f64459 100644
--- a/source/dnode/vnode/src/tsdb/tsdbOpen.c
+++ b/source/dnode/vnode/src/tsdb/tsdbOpen.c
@@ -88,7 +88,7 @@ _err:
 int tsdbClose(STsdb **pTsdb) {
   if (*pTsdb) {
     taosThreadRwlockWrlock(&(*pTsdb)->rwLock);
-    tsdbMemTableDestroy((*pTsdb)->mem);
+    tsdbMemTableDestroy((*pTsdb)->mem, true);
     (*pTsdb)->mem = NULL;
     taosThreadRwlockUnlock(&(*pTsdb)->rwLock);
 
diff --git a/source/dnode/vnode/src/tsdb/tsdbRead.c b/source/dnode/vnode/src/tsdb/tsdbRead.c
index e658d10b3f..5ba44decb4 100644
--- a/source/dnode/vnode/src/tsdb/tsdbRead.c
+++ b/source/dnode/vnode/src/tsdb/tsdbRead.c
@@ -3953,7 +3953,7 @@ void tsdbReaderClose(STsdbReader* pReader) {
   }
 
   qTrace("tsdb/reader: %p, untake snapshot", pReader);
-  tsdbUntakeReadSnap(pReader, pReader->pReadSnap);
+  tsdbUntakeReadSnap(pReader, pReader->pReadSnap, true);
 
   taosThreadMutexDestroy(&pReader->readerMutex);
 
@@ -4001,7 +4001,8 @@ int32_t tsdbReaderSuspend(STsdbReader* pReader) {
   if (pStatus->loadFromFile) {
     SFileDataBlockInfo* pBlockInfo = getCurrentBlockInfo(&pReader->status.blockIter);
     if (pBlockInfo != NULL) {
-      pBlockScanInfo = taosHashGet(pStatus->pTableMap, &pBlockInfo->uid, sizeof(pBlockInfo->uid));
+      pBlockScanInfo =
+          *(STableBlockScanInfo**)taosHashGet(pStatus->pTableMap, &pBlockInfo->uid, sizeof(pBlockInfo->uid));
       if (pBlockScanInfo == NULL) {
         code = TSDB_CODE_INVALID_PARA;
         tsdbError("failed to locate the uid:%" PRIu64 " in query table uid list, total tables:%d, %s", pBlockInfo->uid,
@@ -4015,20 +4016,28 @@ int32_t tsdbReaderSuspend(STsdbReader* pReader) {
     tsdbDataFReaderClose(&pReader->pFileReader);
 
     // resetDataBlockScanInfo excluding lastKey
-    STableBlockScanInfo* p = NULL;
+    STableBlockScanInfo** p = NULL;
 
     while ((p = taosHashIterate(pStatus->pTableMap, p)) != NULL) {
-      p->iterInit = false;
-      p->iiter.hasVal = false;
-      if (p->iter.iter != NULL) {
-        p->iter.iter = tsdbTbDataIterDestroy(p->iter.iter);
+      STableBlockScanInfo* pInfo = *(STableBlockScanInfo**)p;
+
+      pInfo->iterInit = false;
+      pInfo->iter.hasVal = false;
+      pInfo->iiter.hasVal = false;
+
+      if (pInfo->iter.iter != NULL) {
+        pInfo->iter.iter = tsdbTbDataIterDestroy(pInfo->iter.iter);
       }
 
-      p->delSkyline = taosArrayDestroy(p->delSkyline);
-      // p->lastKey = ts;
+      if (pInfo->iiter.iter != NULL) {
+        pInfo->iiter.iter = tsdbTbDataIterDestroy(pInfo->iiter.iter);
+      }
+
+      pInfo->delSkyline = taosArrayDestroy(pInfo->delSkyline);
+      // pInfo->lastKey = ts;
     }
   } else {
-    pBlockScanInfo = *pStatus->pTableIter;
+    pBlockScanInfo = pStatus->pTableIter == NULL ? NULL : *pStatus->pTableIter;
     if (pBlockScanInfo) {
       // save lastKey to restore memory iterator
       STimeWindow w = pReader->pResBlock->info.window;
@@ -4052,11 +4061,13 @@ int32_t tsdbReaderSuspend(STsdbReader* pReader) {
     }
   }
 
-  tsdbUntakeReadSnap(pReader, pReader->pReadSnap);
+  tsdbUntakeReadSnap(pReader, pReader->pReadSnap, false);
+  pReader->pReadSnap = NULL;
 
   pReader->suspended = true;
 
-  tsdbDebug("reader: %p suspended uid %" PRIu64 " in this query %s", pReader, pBlockScanInfo->uid, pReader->idStr);
+  tsdbDebug("reader: %p suspended uid %" PRIu64 " in this query %s", pReader, pBlockScanInfo ? pBlockScanInfo->uid : 0,
+            pReader->idStr);
   return code;
 
 _err:
@@ -4068,18 +4079,24 @@ static int32_t tsdbSetQueryReseek(void* pQHandle) {
   int32_t      code = 0;
   STsdbReader* pReader = pQHandle;
 
-  taosThreadMutexLock(&pReader->readerMutex);
+  code = taosThreadMutexTryLock(&pReader->readerMutex);
+  if (code == 0) {
+    if (pReader->suspended) {
+      taosThreadMutexUnlock(&pReader->readerMutex);
+      return code;
+    }
+
+    tsdbReaderSuspend(pReader);
 
-  if (pReader->suspended) {
     taosThreadMutexUnlock(&pReader->readerMutex);
+
     return code;
+  } else if (code == EBUSY) {
+    return TSDB_CODE_VND_QUERY_BUSY;
+  } else {
+    terrno = TAOS_SYSTEM_ERROR(code);
+    return TSDB_CODE_FAILED;
   }
-
-  tsdbReaderSuspend(pReader);
-
-  taosThreadMutexUnlock(&pReader->readerMutex);
-
-  return code;
 }
 
 int32_t tsdbReaderResume(STsdbReader* pReader) {
@@ -4428,17 +4445,18 @@ SSDataBlock* tsdbRetrieveDataBlock(STsdbReader* pReader, SArray* pIdList) {
 int32_t tsdbReaderReset(STsdbReader* pReader, SQueryTableDataCond* pCond) {
   SReaderStatus* pStatus = &pReader->status;
 
-  qTrace("tsdb/read: %p, take read mutex", pReader);
+  qTrace("tsdb/reader-reset: %p, take read mutex", pReader);
   taosThreadMutexLock(&pReader->readerMutex);
 
   if (pReader->suspended) {
     tsdbReaderResume(pReader);
   }
 
-  taosThreadMutexUnlock(&pReader->readerMutex);
-
   if (isEmptyQueryTimeWindow(&pReader->window) || pReader->pReadSnap == NULL) {
     tsdbDebug("tsdb reader reset return %p", pReader->pReadSnap);
+
+    taosThreadMutexUnlock(&pReader->readerMutex);
+
     return TSDB_CODE_SUCCESS;
   }
 
@@ -4474,6 +4492,9 @@ int32_t tsdbReaderReset(STsdbReader* pReader, SQueryTableDataCond* pCond) {
     if (code != TSDB_CODE_SUCCESS) {
       tsdbError("%p reset reader failed, numOfTables:%d, query range:%" PRId64 " - %" PRId64 " in query %s", pReader,
                 numOfTables, pReader->window.skey, pReader->window.ekey, pReader->idStr);
+
+      taosThreadMutexUnlock(&pReader->readerMutex);
+
       return code;
     }
   }
@@ -4483,6 +4504,8 @@ int32_t tsdbReaderReset(STsdbReader* pReader, SQueryTableDataCond* pCond) {
             pReader, pReader->suid, numOfTables, pCond->twindows.skey, pReader->window.skey, pReader->window.ekey,
             pReader->idStr);
 
+  taosThreadMutexUnlock(&pReader->readerMutex);
+
   return code;
 }
 
@@ -4639,68 +4662,91 @@ int32_t tsdbGetTableSchema(SVnode* pVnode, int64_t uid, STSchema** pSchema, int6
   return TSDB_CODE_SUCCESS;
 }
 
-int32_t tsdbTakeReadSnap(STsdbReader* pReader, _tsdb_reseek_func_t reseek, STsdbReadSnap** ppSnap) {
+int32_t tsdbTakeReadSnap(STsdbReader* pReader, _query_reseek_func_t reseek, STsdbReadSnap** ppSnap) {
   int32_t        code = 0;
   STsdb*         pTsdb = pReader->pTsdb;
   SVersionRange* pRange = &pReader->verRange;
 
   // alloc
-  *ppSnap = (STsdbReadSnap*)taosMemoryCalloc(1, sizeof(STsdbReadSnap));
-  if (*ppSnap == NULL) {
+  STsdbReadSnap* pSnap = (STsdbReadSnap*)taosMemoryCalloc(1, sizeof(*pSnap));
+  if (pSnap == NULL) {
     code = TSDB_CODE_OUT_OF_MEMORY;
     goto _exit;
   }
 
   // lock
-  code = taosThreadRwlockRdlock(&pTsdb->rwLock);
-  if (code) {
-    code = TAOS_SYSTEM_ERROR(code);
-    goto _exit;
-  }
+  taosThreadRwlockRdlock(&pTsdb->rwLock);
 
   // take snapshot
   if (pTsdb->mem && (pRange->minVer <= pTsdb->mem->maxVer && pRange->maxVer >= pTsdb->mem->minVer)) {
-    tsdbRefMemTable(pTsdb->mem, pReader, reseek, &(*ppSnap)->pNode);
-    (*ppSnap)->pMem = pTsdb->mem;
+    pSnap->pMem = pTsdb->mem;
+    pSnap->pNode = taosMemoryMalloc(sizeof(*pSnap->pNode));
+    if (pSnap->pNode == NULL) {
+      taosThreadRwlockUnlock(&pTsdb->rwLock);
+      code = TSDB_CODE_OUT_OF_MEMORY;
+      goto _exit;
+    }
+    pSnap->pNode->pQHandle = pReader;
+    pSnap->pNode->reseek = reseek;
+
+    tsdbRefMemTable(pTsdb->mem, pSnap->pNode);
   }
 
   if (pTsdb->imem && (pRange->minVer <= pTsdb->imem->maxVer && pRange->maxVer >= pTsdb->imem->minVer)) {
-    tsdbRefMemTable(pTsdb->imem, pReader, reseek, &(*ppSnap)->pINode);
-    (*ppSnap)->pIMem = pTsdb->imem;
+    pSnap->pIMem = pTsdb->imem;
+    pSnap->pINode = taosMemoryMalloc(sizeof(*pSnap->pINode));
+    if (pSnap->pINode == NULL) {
+      taosThreadRwlockUnlock(&pTsdb->rwLock);
+      code = TSDB_CODE_OUT_OF_MEMORY;
+      goto _exit;
+    }
+    pSnap->pINode->pQHandle = pReader;
+    pSnap->pINode->reseek = reseek;
+
+    tsdbRefMemTable(pTsdb->imem, pSnap->pINode);
   }
 
   // fs
-  code = tsdbFSRef(pTsdb, &(*ppSnap)->fs);
+  code = tsdbFSRef(pTsdb, &pSnap->fs);
   if (code) {
     taosThreadRwlockUnlock(&pTsdb->rwLock);
     goto _exit;
   }
 
   // unlock
-  code = taosThreadRwlockUnlock(&pTsdb->rwLock);
-  if (code) {
-    code = TAOS_SYSTEM_ERROR(code);
-    goto _exit;
-  }
+  taosThreadRwlockUnlock(&pTsdb->rwLock);
 
   tsdbTrace("vgId:%d, take read snapshot", TD_VID(pTsdb->pVnode));
+
 _exit:
+  if (code) {
+    *ppSnap = NULL;
+    if (pSnap) {
+      if (pSnap->pNode) taosMemoryFree(pSnap->pNode);
+      if (pSnap->pINode) taosMemoryFree(pSnap->pINode);
+      taosMemoryFree(pSnap);
+    }
+  } else {
+    *ppSnap = pSnap;
+  }
   return code;
 }
 
-void tsdbUntakeReadSnap(STsdbReader* pReader, STsdbReadSnap* pSnap) {
+void tsdbUntakeReadSnap(STsdbReader* pReader, STsdbReadSnap* pSnap, bool proactive) {
   STsdb* pTsdb = pReader->pTsdb;
 
   if (pSnap) {
     if (pSnap->pMem) {
-      tsdbUnrefMemTable(pSnap->pMem, pSnap->pNode);
+      tsdbUnrefMemTable(pSnap->pMem, pSnap->pNode, proactive);
     }
 
     if (pSnap->pIMem) {
-      tsdbUnrefMemTable(pSnap->pIMem, pSnap->pINode);
+      tsdbUnrefMemTable(pSnap->pIMem, pSnap->pINode, proactive);
     }
 
     tsdbFSUnref(pTsdb, &pSnap->fs);
+    if (pSnap->pNode) taosMemoryFree(pSnap->pNode);
+    if (pSnap->pINode) taosMemoryFree(pSnap->pINode);
     taosMemoryFree(pSnap);
   }
   tsdbTrace("vgId:%d, untake read snapshot", TD_VID(pTsdb->pVnode));
diff --git a/source/dnode/vnode/src/vnd/vnodeBufPool.c b/source/dnode/vnode/src/vnd/vnodeBufPool.c
index 139ee23266..80a422ca3b 100644
--- a/source/dnode/vnode/src/vnd/vnodeBufPool.c
+++ b/source/dnode/vnode/src/vnd/vnodeBufPool.c
@@ -16,9 +16,7 @@
 #include "vnd.h"
 
 /* ------------------------ STRUCTURES ------------------------ */
-#define VNODE_BUFPOOL_SEGMENTS 3
-
-static int vnodeBufPoolCreate(SVnode *pVnode, int64_t size, SVBufPool **ppPool) {
+static int vnodeBufPoolCreate(SVnode *pVnode, int32_t id, int64_t size, SVBufPool **ppPool) {
   SVBufPool *pPool;
 
   pPool = taosMemoryMalloc(sizeof(SVBufPool) + size);
@@ -26,6 +24,21 @@ static int vnodeBufPoolCreate(SVnode *pVnode, int64_t size, SVBufPool **ppPool)
     terrno = TSDB_CODE_OUT_OF_MEMORY;
     return -1;
   }
+  memset(pPool, 0, sizeof(SVBufPool));
+
+  // query handle list
+  taosThreadMutexInit(&pPool->mutex, NULL);
+  pPool->nQuery = 0;
+  pPool->qList.pNext = &pPool->qList;
+  pPool->qList.ppNext = &pPool->qList.pNext;
+
+  pPool->pVnode = pVnode;
+  pPool->id = id;
+  pPool->ptr = pPool->node.data;
+  pPool->pTail = &pPool->node;
+  pPool->node.prev = NULL;
+  pPool->node.pnext = &pPool->pTail;
+  pPool->node.size = size;
 
   if (VND_IS_RSMA(pVnode)) {
     pPool->lock = taosMemoryMalloc(sizeof(TdThreadSpinlock));
@@ -44,16 +57,6 @@ static int vnodeBufPoolCreate(SVnode *pVnode, int64_t size, SVBufPool **ppPool)
     pPool->lock = NULL;
   }
 
-  pPool->next = NULL;
-  pPool->pVnode = pVnode;
-  pPool->nRef = 0;
-  pPool->size = 0;
-  pPool->ptr = pPool->node.data;
-  pPool->pTail = &pPool->node;
-  pPool->node.prev = NULL;
-  pPool->node.pnext = &pPool->pTail;
-  pPool->node.size = size;
-
   *ppPool = pPool;
   return 0;
 }
@@ -64,27 +67,25 @@ static int vnodeBufPoolDestroy(SVBufPool *pPool) {
     taosThreadSpinDestroy(pPool->lock);
     taosMemoryFree((void *)pPool->lock);
   }
+  taosThreadMutexDestroy(&pPool->mutex);
   taosMemoryFree(pPool);
   return 0;
 }
 
 int vnodeOpenBufPool(SVnode *pVnode) {
-  SVBufPool *pPool = NULL;
-  int64_t    size = pVnode->config.szBuf / VNODE_BUFPOOL_SEGMENTS;
-
-  ASSERT(pVnode->pPool == NULL);
+  int64_t size = pVnode->config.szBuf / VNODE_BUFPOOL_SEGMENTS;
 
   for (int i = 0; i < VNODE_BUFPOOL_SEGMENTS; i++) {
     // create pool
-    if (vnodeBufPoolCreate(pVnode, size, &pPool)) {
+    if (vnodeBufPoolCreate(pVnode, i, size, &pVnode->aBufPool[i])) {
       vError("vgId:%d, failed to open vnode buffer pool since %s", TD_VID(pVnode), tstrerror(terrno));
       vnodeCloseBufPool(pVnode);
       return -1;
     }
 
-    // add pool to vnode
-    pPool->next = pVnode->pPool;
-    pVnode->pPool = pPool;
+    // add to free list
+    pVnode->aBufPool[i]->freeNext = pVnode->freeList;
+    pVnode->freeList = pVnode->aBufPool[i];
   }
 
   vDebug("vgId:%d, vnode buffer pool is opened, size:%" PRId64, TD_VID(pVnode), size);
@@ -92,23 +93,19 @@ int vnodeOpenBufPool(SVnode *pVnode) {
 }
 
 int vnodeCloseBufPool(SVnode *pVnode) {
-  SVBufPool *pPool;
-
-  for (pPool = pVnode->pPool; pPool; pPool = pVnode->pPool) {
-    pVnode->pPool = pPool->next;
-    vnodeBufPoolDestroy(pPool);
+  for (int32_t i = 0; i < VNODE_BUFPOOL_SEGMENTS; i++) {
+    if (pVnode->aBufPool[i]) {
+      vnodeBufPoolDestroy(pVnode->aBufPool[i]);
+      pVnode->aBufPool[i] = NULL;
+    }
   }
 
-  if (pVnode->inUse) {
-    vnodeBufPoolDestroy(pVnode->inUse);
-    pVnode->inUse = NULL;
-  }
   vDebug("vgId:%d, vnode buffer pool is closed", TD_VID(pVnode));
-
   return 0;
 }
 
 void vnodeBufPoolReset(SVBufPool *pPool) {
+  ASSERT(pPool->nQuery == 0);
   for (SVBufPoolNode *pNode = pPool->pTail; pNode->prev; pNode = pPool->pTail) {
     ASSERT(pNode->pnext == &pPool->pTail);
     pNode->prev->pnext = &pPool->pTail;
@@ -215,35 +212,121 @@ void vnodeBufPoolRef(SVBufPool *pPool) {
   ASSERT(nRef > 0);
 }
 
-void vnodeBufPoolUnRef(SVBufPool *pPool) {
-  if (pPool == NULL) {
-    return;
+void vnodeBufPoolAddToFreeList(SVBufPool *pPool) {
+  SVnode *pVnode = pPool->pVnode;
+
+  int64_t size = pVnode->config.szBuf / VNODE_BUFPOOL_SEGMENTS;
+  if (pPool->node.size != size) {
+    SVBufPool *pNewPool = NULL;
+    if (vnodeBufPoolCreate(pVnode, pPool->id, size, &pNewPool) < 0) {
+      vWarn("vgId:%d failed to change buffer pool of id %d size from %" PRId64 " to %" PRId64 " since %s",
+            TD_VID(pVnode), pPool->id, pPool->node.size, size, tstrerror(errno));
+    } else {
+      vInfo("vgId:%d buffer pool of id %d size changed from %" PRId64 " to %" PRId64, TD_VID(pVnode), pPool->id,
+            pPool->node.size, size);
+
+      vnodeBufPoolDestroy(pPool);
+      pPool = pNewPool;
+      pVnode->aBufPool[pPool->id] = pPool;
+    }
   }
-  int32_t nRef = atomic_sub_fetch_32(&pPool->nRef, 1);
-  if (nRef == 0) {
-    SVnode *pVnode = pPool->pVnode;
 
-    vnodeBufPoolReset(pPool);
+  // add to free list
+  vDebug("vgId:%d buffer pool %p of id %d is added to free list", TD_VID(pVnode), pPool, pPool->id);
+  vnodeBufPoolReset(pPool);
+  pPool->freeNext = pVnode->freeList;
+  pVnode->freeList = pPool;
+  taosThreadCondSignal(&pVnode->poolNotEmpty);
+}
 
-    taosThreadMutexLock(&pVnode->mutex);
+void vnodeBufPoolUnRef(SVBufPool *pPool, bool proactive) {
+  if (pPool == NULL) return;
 
-    int64_t size = pVnode->config.szBuf / VNODE_BUFPOOL_SEGMENTS;
-    if (pPool->node.size != size) {
-      SVBufPool *pPoolT = NULL;
-      if (vnodeBufPoolCreate(pVnode, size, &pPoolT) < 0) {
-        vWarn("vgId:%d, try to change buf pools size from %" PRId64 " to %" PRId64 " since %s", TD_VID(pVnode),
-              pPool->node.size, size, tstrerror(errno));
-      } else {
-        vnodeBufPoolDestroy(pPool);
-        pPool = pPoolT;
-        vDebug("vgId:%d, change buf pools size from %" PRId64 " to %" PRId64, TD_VID(pVnode), pPool->node.size, size);
-      }
+  SVnode *pVnode = pPool->pVnode;
+
+  if (proactive) taosThreadMutexLock(&pVnode->mutex);
+
+  if (atomic_sub_fetch_32(&pPool->nRef, 1) > 0) goto _exit;
+
+  // remove from recycle queue or on-recycle position
+  if (pVnode->onRecycle == pPool) {
+    pVnode->onRecycle = NULL;
+  } else {
+    ASSERT(proactive);
+
+    if (pPool->recyclePrev) {
+      pPool->recyclePrev->recycleNext = pPool->recycleNext;
+    } else {
+      pVnode->recycleHead = pPool->recycleNext;
     }
 
-    pPool->next = pVnode->pPool;
-    pVnode->pPool = pPool;
-    taosThreadCondSignal(&pVnode->poolNotEmpty);
-
-    taosThreadMutexUnlock(&pVnode->mutex);
+    if (pPool->recycleNext) {
+      pPool->recycleNext->recyclePrev = pPool->recyclePrev;
+    } else {
+      pVnode->recycleTail = pPool->recyclePrev;
+    }
+    pPool->recyclePrev = pPool->recycleNext = NULL;
   }
+
+  vnodeBufPoolAddToFreeList(pPool);
+
+_exit:
+  if (proactive) taosThreadMutexUnlock(&pVnode->mutex);
+  return;
 }
+
+int32_t vnodeBufPoolRegisterQuery(SVBufPool *pPool, SQueryNode *pQNode) {
+  int32_t code = 0;
+
+  taosThreadMutexLock(&pPool->mutex);
+
+  pQNode->pNext = pPool->qList.pNext;
+  pQNode->ppNext = &pPool->qList.pNext;
+  pPool->qList.pNext->ppNext = &pQNode->pNext;
+  pPool->qList.pNext = pQNode;
+  pPool->nQuery++;
+
+  taosThreadMutexUnlock(&pPool->mutex);
+
+_exit:
+  return code;
+}
+
+void vnodeBufPoolDeregisterQuery(SVBufPool *pPool, SQueryNode *pQNode, bool proactive) {
+  int32_t code = 0;
+
+  if (proactive) taosThreadMutexLock(&pPool->mutex);
+
+  pQNode->pNext->ppNext = pQNode->ppNext;
+  *pQNode->ppNext = pQNode->pNext;
+  pPool->nQuery--;
+
+  if (proactive) taosThreadMutexUnlock(&pPool->mutex);
+}
+
+int32_t vnodeBufPoolRecycle(SVBufPool *pPool) {
+  int32_t code = 0;
+
+  SVnode *pVnode = pPool->pVnode;
+
+  vDebug("vgId:%d recycle buffer pool %p of id %d", TD_VID(pVnode), pPool, pPool->id);
+
+  taosThreadMutexLock(&pPool->mutex);
+
+  SQueryNode *pNode = pPool->qList.pNext;
+  while (pNode != &pPool->qList) {
+    SQueryNode *pTNode = pNode->pNext;
+
+    int32_t rc = pNode->reseek(pNode->pQHandle);
+    if (rc == 0 || rc == TSDB_CODE_VND_QUERY_BUSY) {
+      pNode = pTNode;
+    } else {
+      code = rc;
+      goto _exit;
+    }
+  }
+
+_exit:
+  taosThreadMutexUnlock(&pPool->mutex);
+  return code;
+}
\ No newline at end of file
diff --git a/source/dnode/vnode/src/vnd/vnodeCommit.c b/source/dnode/vnode/src/vnd/vnodeCommit.c
index b42bdf564d..63c05ce88c 100644
--- a/source/dnode/vnode/src/vnd/vnodeCommit.c
+++ b/source/dnode/vnode/src/vnd/vnodeCommit.c
@@ -21,41 +21,128 @@
 static int vnodeEncodeInfo(const SVnodeInfo *pInfo, char **ppData);
 static int vnodeCommitImpl(SCommitInfo *pInfo);
 
-int vnodeBegin(SVnode *pVnode) {
-  // alloc buffer pool
-  taosThreadMutexLock(&pVnode->mutex);
+#define WAIT_TIME_MILI_SEC 10  // miliseconds
 
-  while (pVnode->pPool == NULL) {
-    taosThreadCondWait(&pVnode->poolNotEmpty, &pVnode->mutex);
+static int32_t vnodeTryRecycleBufPool(SVnode *pVnode) {
+  int32_t code = 0;
+
+  if (pVnode->onRecycle == NULL) {
+    if (pVnode->recycleHead == NULL) {
+      vDebug("vgId:%d no recyclable buffer pool", TD_VID(pVnode));
+      goto _exit;
+    } else {
+      vDebug("vgId:%d buffer pool %p of id %d on recycle queue, try to recycle", TD_VID(pVnode), pVnode->recycleHead,
+             pVnode->recycleHead->id);
+
+      pVnode->onRecycle = pVnode->recycleHead;
+      if (pVnode->recycleHead == pVnode->recycleTail) {
+        pVnode->recycleHead = pVnode->recycleTail = NULL;
+      } else {
+        pVnode->recycleHead = pVnode->recycleHead->recycleNext;
+        pVnode->recycleHead->recyclePrev = NULL;
+      }
+      pVnode->onRecycle->recycleNext = pVnode->onRecycle->recyclePrev = NULL;
+    }
   }
 
-  pVnode->inUse = pVnode->pPool;
-  pVnode->inUse->nRef = 1;
-  pVnode->pPool = pVnode->inUse->next;
-  pVnode->inUse->next = NULL;
+  code = vnodeBufPoolRecycle(pVnode->onRecycle);
+  if (code) goto _exit;
 
+_exit:
+  if (code) {
+    vError("vgId:%d %s failed since %s", TD_VID(pVnode), __func__, tstrerror(code));
+  }
+  return code;
+}
+static int32_t vnodeGetBufPoolToUse(SVnode *pVnode) {
+  int32_t code = 0;
+  int32_t lino = 0;
+
+  taosThreadMutexLock(&pVnode->mutex);
+
+  int32_t nTry = 0;
+  for (;;) {
+    ++nTry;
+
+    if (pVnode->freeList) {
+      vDebug("vgId:%d allocate free buffer pool on %d try, pPool:%p id:%d", TD_VID(pVnode), nTry, pVnode->freeList,
+             pVnode->freeList->id);
+
+      pVnode->inUse = pVnode->freeList;
+      pVnode->inUse->nRef = 1;
+      pVnode->freeList = pVnode->inUse->freeNext;
+      pVnode->inUse->freeNext = NULL;
+      break;
+    } else {
+      vDebug("vgId:%d no free buffer pool on %d try, try to recycle...", TD_VID(pVnode), nTry);
+      /*
+      code = vnodeTryRecycleBufPool(pVnode);
+      TSDB_CHECK_CODE(code, lino, _exit);
+      */
+      if (pVnode->freeList == NULL) {
+        vDebug("vgId:%d no free buffer pool on %d try, wait %d ms...", TD_VID(pVnode), nTry, WAIT_TIME_MILI_SEC);
+
+        struct timeval  tv;
+        struct timespec ts;
+        taosGetTimeOfDay(&tv);
+        ts.tv_nsec = tv.tv_usec * 1000 + WAIT_TIME_MILI_SEC * 1000000;
+        if (ts.tv_nsec > 999999999l) {
+          ts.tv_sec = tv.tv_sec + 1;
+          ts.tv_nsec -= 1000000000l;
+        } else {
+          ts.tv_sec = tv.tv_sec;
+        }
+
+        int32_t rc = taosThreadCondTimedWait(&pVnode->poolNotEmpty, &pVnode->mutex, &ts);
+        if (rc && rc != ETIMEDOUT) {
+          code = TAOS_SYSTEM_ERROR(rc);
+          TSDB_CHECK_CODE(code, lino, _exit);
+        }
+      }
+    }
+  }
+
+_exit:
   taosThreadMutexUnlock(&pVnode->mutex);
+  if (code) {
+    vError("vgId:%d %s failed at line %d since %s", TD_VID(pVnode), __func__, lino, tstrerror(code));
+  }
+  return code;
+}
+int vnodeBegin(SVnode *pVnode) {
+  int32_t code = 0;
+  int32_t lino = 0;
 
   pVnode->state.commitID++;
+
+  // alloc buffer pool
+  code = vnodeGetBufPoolToUse(pVnode);
+  TSDB_CHECK_CODE(code, lino, _exit);
+
   // begin meta
   if (metaBegin(pVnode->pMeta, META_BEGIN_HEAP_BUFFERPOOL) < 0) {
-    vError("vgId:%d, failed to begin meta since %s", TD_VID(pVnode), tstrerror(terrno));
-    return -1;
+    code = terrno;
+    TSDB_CHECK_CODE(code, lino, _exit);
   }
 
   // begin tsdb
   if (tsdbBegin(pVnode->pTsdb) < 0) {
-    vError("vgId:%d, failed to begin tsdb since %s", TD_VID(pVnode), tstrerror(terrno));
-    return -1;
+    code = terrno;
+    TSDB_CHECK_CODE(code, lino, _exit);
   }
 
   // begin sma
   if (VND_IS_RSMA(pVnode) && smaBegin(pVnode->pSma) < 0) {
-    vError("vgId:%d, failed to begin sma since %s", TD_VID(pVnode), tstrerror(terrno));
-    return -1;
+    code = terrno;
+    TSDB_CHECK_CODE(code, lino, _exit);
   }
 
-  return 0;
+_exit:
+  if (code) {
+    terrno = code;
+    vError("vgId:%d %s failed at line %d since %s", TD_VID(pVnode), __func__, lino, tstrerror(code));
+  }
+  return code;
 }
 
 void vnodeUpdCommitSched(SVnode *pVnode) {
@@ -70,7 +157,7 @@ int vnodeShouldCommit(SVnode *pVnode) {
   }
 
   SVCommitSched *pSched = &pVnode->commitSched;
-  int64_t nowMs = taosGetMonoTimestampMs();
+  int64_t        nowMs = taosGetMonoTimestampMs();
 
   return (((pVnode->inUse->size > pVnode->inUse->node.size) && (pSched->commitMs + SYNC_VND_COMMIT_MIN_MS < nowMs)) ||
           (pVnode->inUse->size > 0 && pSched->commitMs + pSched->maxWaitMs < nowMs));
@@ -209,6 +296,12 @@ static int32_t vnodePrepareCommit(SVnode *pVnode, SCommitInfo *pInfo) {
 
   tsem_wait(&pVnode->canCommit);
 
+  taosThreadMutexLock(&pVnode->mutex);
+  ASSERT(pVnode->onCommit == NULL);
+  pVnode->onCommit = pVnode->inUse;
+  pVnode->inUse = NULL;
+  taosThreadMutexUnlock(&pVnode->mutex);
+
   pVnode->state.commitTerm = pVnode->state.applyTerm;
 
   pInfo->info.config = pVnode->config;
@@ -238,9 +331,6 @@ static int32_t vnodePrepareCommit(SVnode *pVnode, SCommitInfo *pInfo) {
   code = smaPrepareAsyncCommit(pVnode->pSma);
   if (code) goto _exit;
 
-  vnodeBufPoolUnRef(pVnode->inUse);
-  pVnode->inUse = NULL;
-
 _exit:
   if (code) {
     vError("vgId:%d, %s failed at line %d since %s, commit id:%" PRId64, TD_VID(pVnode), __func__, lino,
@@ -251,19 +341,48 @@ _exit:
 
   return code;
 }
+static void vnodeReturnBufPool(SVnode *pVnode) {
+  taosThreadMutexLock(&pVnode->mutex);
 
+  SVBufPool *pPool = pVnode->onCommit;
+  int32_t    nRef = atomic_sub_fetch_32(&pPool->nRef, 1);
+
+  pVnode->onCommit = NULL;
+  if (nRef == 0) {
+    vnodeBufPoolAddToFreeList(pPool);
+  } else if (nRef > 0) {
+    vDebug("vgId:%d buffer pool %p of id %d is added to recycle queue", TD_VID(pVnode), pPool, pPool->id);
+
+    if (pVnode->recycleTail == NULL) {
+      pPool->recyclePrev = pPool->recycleNext = NULL;
+      pVnode->recycleHead = pVnode->recycleTail = pPool;
+    } else {
+      pPool->recyclePrev = pVnode->recycleTail;
+      pPool->recycleNext = NULL;
+      pVnode->recycleTail->recycleNext = pPool;
+      pVnode->recycleTail = pPool;
+    }
+  } else {
+    ASSERT(0);
+  }
+
+  taosThreadMutexUnlock(&pVnode->mutex);
+}
 static int32_t vnodeCommitTask(void *arg) {
   int32_t code = 0;
 
   SCommitInfo *pInfo = (SCommitInfo *)arg;
+  SVnode      *pVnode = pInfo->pVnode;
 
   // commit
   code = vnodeCommitImpl(pInfo);
   if (code) goto _exit;
 
+  vnodeReturnBufPool(pVnode);
+
 _exit:
   // end commit
-  tsem_post(&pInfo->pVnode->canCommit);
+  tsem_post(&pVnode->canCommit);
   taosMemoryFree(pInfo);
   return code;
 }
diff --git a/source/dnode/vnode/src/vnd/vnodeOpen.c b/source/dnode/vnode/src/vnd/vnodeOpen.c
index 8c07d0cec7..52c1f45762 100644
--- a/source/dnode/vnode/src/vnd/vnodeOpen.c
+++ b/source/dnode/vnode/src/vnd/vnodeOpen.c
@@ -240,7 +240,7 @@ _err:
   if (pVnode->pTsdb) tsdbClose(&pVnode->pTsdb);
   if (pVnode->pSma) smaClose(pVnode->pSma);
   if (pVnode->pMeta) metaClose(pVnode->pMeta);
-  if (pVnode->pPool) vnodeCloseBufPool(pVnode);
+  if (pVnode->freeList) vnodeCloseBufPool(pVnode);
 
   tsem_destroy(&(pVnode->canCommit));
   taosMemoryFree(pVnode);
diff --git a/source/dnode/vnode/src/vnd/vnodeSvr.c b/source/dnode/vnode/src/vnd/vnodeSvr.c
index deb9da2050..6abc144b91 100644
--- a/source/dnode/vnode/src/vnd/vnodeSvr.c
+++ b/source/dnode/vnode/src/vnd/vnodeSvr.c
@@ -191,13 +191,13 @@ int32_t vnodeProcessWriteMsg(SVnode *pVnode, SRpcMsg *pMsg, int64_t version, SRp
   void   *pReq;
   int32_t len;
   int32_t ret;
-
+  /*
   if (!pVnode->inUse) {
     terrno = TSDB_CODE_VND_NO_AVAIL_BUFPOOL;
     vError("vgId:%d, not ready to write since %s", TD_VID(pVnode), terrstr());
     return -1;
   }
-
+  */
   if (version <= pVnode->state.applied) {
     vError("vgId:%d, duplicate write request. version: %" PRId64 ", applied: %" PRId64 "", TD_VID(pVnode), version,
            pVnode->state.applied);
@@ -1001,7 +1001,7 @@ static int32_t vnodeProcessSubmitReq(SVnode *pVnode, int64_t version, void *pReq
           code = terrno;
           goto _exit;
         }
-        pSubmitTbData->uid = pSubmitTbData->pCreateTbReq->uid;   // update uid if table exist for using below
+        pSubmitTbData->uid = pSubmitTbData->pCreateTbReq->uid;  // update uid if table exist for using below
       }
     }
 
diff --git a/source/util/src/terror.c b/source/util/src/terror.c
index a142bb76d7..bab3edc870 100644
--- a/source/util/src/terror.c
+++ b/source/util/src/terror.c
@@ -320,6 +320,7 @@ TAOS_DEFINE_ERROR(TSDB_CODE_VND_COL_SUBSCRIBED,           "Table column is subsc
 TAOS_DEFINE_ERROR(TSDB_CODE_VND_NO_AVAIL_BUFPOOL,         "No availabe buffer pool")
 TAOS_DEFINE_ERROR(TSDB_CODE_VND_STOPPED,                  "Vnode stopped")
 TAOS_DEFINE_ERROR(TSDB_CODE_VND_DUP_REQUEST,              "Duplicate write request")
+TAOS_DEFINE_ERROR(TSDB_CODE_VND_QUERY_BUSY,               "Query busy")
 
 // tsdb
 TAOS_DEFINE_ERROR(TSDB_CODE_TDB_INVALID_TABLE_ID,         "Invalid table ID")