diff --git a/src/client/inc/tsclient.h b/src/client/inc/tsclient.h
index fa215db2702f63aff4c704f8393255a94987d681..78b0bcce9c5df3cbb0ea9b0528a529dfcdfe59b2 100644
--- a/src/client/inc/tsclient.h
+++ b/src/client/inc/tsclient.h
@@ -30,6 +30,7 @@ extern "C" {
 #include "tsqlfunction.h"
 #include "tutil.h"
 #include "tcache.h"
+#include "tref.h"
 
 #include "qExecutor.h"
 #include "qSqlparser.h"
@@ -446,7 +447,7 @@ void tscFreeSqlObj(SSqlObj *pSql);
 void tscFreeRegisteredSqlObj(void *pSql);
 void tscFreeTableMetaHelper(void *pTableMeta);
 
-void tscCloseTscObj(STscObj *pObj);
+void tscCloseTscObj(void *pObj);
 
 // todo move to taos? or create a new file: taos_internal.h
 TAOS *taos_connect_a(char *ip, char *user, char *pass, char *db, uint16_t port, void (*fp)(void *, TAOS_RES *, int),
@@ -516,6 +517,7 @@ extern void *    tscQhandle;
 extern int       tscKeepConn[];
 extern int       tsInsertHeadSize;
 extern int       tscNumOfThreads;
+extern int       tscRefId;
   
 extern SRpcCorEpSet tscMgmtEpSet;
 
diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index a0841fa2344682facb4a6dc8666716e38a31ea1d..b9c0698fcd8143b389b279e7760fca316c8cb980 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -190,18 +190,19 @@ void tscProcessHeartBeatRsp(void *param, TAOS_RES *tres, int code) {
 
 void tscProcessActivityTimer(void *handle, void *tmrId) {
   STscObj *pObj = (STscObj *)handle;
-  if (pObj == NULL || pObj->signature != pObj) {
+
+  int ret = taosAcquireRef(tscRefId, pObj);
+  if (ret < 0) {
+    tscTrace("%p failed to acquire TSC obj, reason:%s", pObj, tstrerror(ret));
     return;
   }
 
   SSqlObj* pHB = pObj->pHb;
-  if (pObj->pTimer != tmrId || pHB == NULL) {
-    return;
-  }
 
   void** p = taosCacheAcquireByKey(tscObjCache, &pHB, sizeof(TSDB_CACHE_PTR_TYPE));
   if (p == NULL) {
     tscWarn("%p HB object has been released already", pHB);
+    taosReleaseRef(tscRefId, pObj);
     return;
   }
 
@@ -213,6 +214,8 @@ void tscProcessActivityTimer(void *handle, void *tmrId) {
   if (code != TSDB_CODE_SUCCESS) {
     tscError("%p failed to sent HB to server, reason:%s", pHB, tstrerror(code));
   }
+
+  taosReleaseRef(tscRefId, pObj);
 }
 
 int tscSendMsgToServer(SSqlObj *pSql) {
diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index 8cac9b3398a0bc4569b52acc7858bbc1e50de542..89dfa24e8fe2cef32673fb2016fa538f218d1bcf 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -161,6 +161,7 @@ static SSqlObj *taosConnectImpl(const char *ip, const char *user, const char *pa
   registerSqlObj(pSql);
   tsInsertHeadSize = sizeof(SMsgDesc) + sizeof(SSubmitMsg);
 
+  taosAddRef(tscRefId, pObj);
   return pSql;
 }
 
@@ -296,7 +297,8 @@ void taos_close(TAOS *taos) {
   }
 
   tscDebug("%p all sqlObj are freed, free tscObj and close dnodeConn:%p", pObj, pObj->pDnodeConn);
-  tscCloseTscObj(pObj);
+
+  taosRemoveRef(tscRefId, pObj);
 }
 
 void waitForQueryRsp(void *param, TAOS_RES *tres, int code) {
diff --git a/src/client/src/tscSystem.c b/src/client/src/tscSystem.c
index 47c2d35a75cba4787e00c645e2f242ae24788df7..bff5062f16d4d6d04638c3de2f6738e159b77a1f 100644
--- a/src/client/src/tscSystem.c
+++ b/src/client/src/tscSystem.c
@@ -36,6 +36,7 @@ void *  tscTmr;
 void *  tscQhandle;
 void *  tscCheckDiskUsageTmr;
 int     tsInsertHeadSize;
+int     tscRefId;
 
 int tscNumOfThreads;
 
@@ -146,6 +147,8 @@ void taos_init_imp(void) {
     tscObjCache = taosCacheInit(TSDB_CACHE_PTR_KEY, refreshTime / 2, false, tscFreeRegisteredSqlObj, "sqlObj");
   }
 
+  tscRefId = taosOpenRef(200, tscCloseTscObj);
+
   tscDebug("client is initialized successfully");
 }
 
@@ -165,6 +168,7 @@ void taos_cleanup() {
     tscQhandle = NULL;
   }
 
+  taosCloseRef(tscRefId);
   taosCleanupKeywordsTable();
   taosCloseLog();
   
diff --git a/src/client/src/tscUtil.c b/src/client/src/tscUtil.c
index b60bf958a84bcefd8fb14970923f4af1074b7a6f..e6ad2bb5eb63cb3414f61f65c31cbec66785fd80 100644
--- a/src/client/src/tscUtil.c
+++ b/src/client/src/tscUtil.c
@@ -404,7 +404,7 @@ void tscFreeRegisteredSqlObj(void *pSql) {
   tscDebug("%p free sqlObj completed, tscObj:%p ref:%d", *p, pTscObj, ref);
   if (ref == 0) {
     tscDebug("%p all sqlObj freed, free tscObj:%p", *p, pTscObj);
-    tscCloseTscObj(pTscObj);
+    taosRemoveRef(tscRefId, pTscObj);
   }
 }
 
@@ -786,8 +786,8 @@ int32_t tscMergeTableDataBlocks(SSqlObj* pSql, SArray* pTableDataBlockList) {
 }
 
 // TODO: all subqueries should be freed correctly before close this connection.
-void tscCloseTscObj(STscObj* pObj) {
-  assert(pObj != NULL);
+void tscCloseTscObj(void *param) {
+  STscObj *pObj = param;
 
   pObj->signature = NULL;
   taosTmrStopA(&(pObj->pTimer));
diff --git a/src/connector/go b/src/connector/go
index 8d7bf743852897110cbdcc7c4322cd7a74d4167b..8c58c512b6acda8bcdfa48fdc7140227b5221766 160000
--- a/src/connector/go
+++ b/src/connector/go
@@ -1 +1 @@
-Subproject commit 8d7bf743852897110cbdcc7c4322cd7a74d4167b
+Subproject commit 8c58c512b6acda8bcdfa48fdc7140227b5221766
diff --git a/src/rpc/src/rpcMain.c b/src/rpc/src/rpcMain.c
index 6e9088d9fb82a80bb28857d563ad51f19594e6b7..976a6358182c11aa87c71356919be3223f2ea057 100644
--- a/src/rpc/src/rpcMain.c
+++ b/src/rpc/src/rpcMain.c
@@ -20,6 +20,7 @@
 #include "ttimer.h"
 #include "tutil.h"
 #include "lz4.h"
+#include "tref.h"
 #include "taoserror.h"
 #include "tsocket.h"
 #include "tglobal.h"
@@ -72,7 +73,6 @@ typedef struct {
   SRpcInfo *pRpc;       // associated SRpcInfo
   SRpcEpSet epSet;      // ip list provided by app
   void     *ahandle;    // handle provided by app
-  void     *signature;  // for validation
   struct SRpcConn *pConn; // pConn allocated
   char      msgType;    // message type
   uint8_t  *pCont;      // content provided by app
@@ -132,6 +132,10 @@ int tsRpcMaxRetry;
 int tsRpcHeadSize;
 int tsRpcOverhead;
 
+static int     tsRpcRefId = -1;
+static int32_t tsRpcNum = 0;
+static pthread_once_t tsRpcInit = PTHREAD_ONCE_INIT;
+
 // server:0 client:1  tcp:2 udp:0
 #define RPC_CONN_UDPS   0
 #define RPC_CONN_UDPC   1
@@ -211,14 +215,21 @@ static void  rpcUnlockConn(SRpcConn *pConn);
 static void  rpcAddRef(SRpcInfo *pRpc);
 static void  rpcDecRef(SRpcInfo *pRpc);
 
-void *rpcOpen(const SRpcInit *pInit) {
-  SRpcInfo *pRpc;
+static void rpcInit(void) {
 
   tsProgressTimer = tsRpcTimer/2; 
   tsRpcMaxRetry = tsRpcMaxTime * 1000/tsProgressTimer;
   tsRpcHeadSize = RPC_MSG_OVERHEAD; 
   tsRpcOverhead = sizeof(SRpcReqContext);
 
+  tsRpcRefId = taosOpenRef(200, free);
+}
+ 
+void *rpcOpen(const SRpcInit *pInit) {
+  SRpcInfo *pRpc;
+
+  pthread_once(&tsRpcInit, rpcInit);
+
   pRpc = (SRpcInfo *)calloc(1, sizeof(SRpcInfo));
   if (pRpc == NULL) return NULL;
 
@@ -237,6 +248,8 @@ void *rpcOpen(const SRpcInit *pInit) {
   pRpc->afp = pInit->afp;
   pRpc->refCount = 1;
 
+  atomic_add_fetch_32(&tsRpcNum, 1);
+
   size_t size = sizeof(SRpcConn) * pRpc->sessions;
   pRpc->connList = (SRpcConn *)calloc(1, size);
   if (pRpc->connList == NULL) {
@@ -363,7 +376,6 @@ void rpcSendRequest(void *shandle, const SRpcEpSet *pEpSet, SRpcMsg *pMsg) {
   int contLen = rpcCompressRpcMsg(pMsg->pCont, pMsg->contLen);
   pContext = (SRpcReqContext *) ((char*)pMsg->pCont-sizeof(SRpcHead)-sizeof(SRpcReqContext));
   pContext->ahandle = pMsg->ahandle;
-  pContext->signature = pContext;
   pContext->pRpc = (SRpcInfo *)shandle;
   pContext->epSet = *pEpSet;
   pContext->contLen = contLen;
@@ -386,6 +398,7 @@ void rpcSendRequest(void *shandle, const SRpcEpSet *pEpSet, SRpcMsg *pMsg) {
   // set the handle to pContext, so app can cancel the request
   if (pMsg->handle) *((void **)pMsg->handle) = pContext;
 
+  taosAddRef(tsRpcRefId, pContext);
   rpcSendReqToServer(pRpc, pContext);
 
   return;
@@ -536,14 +549,15 @@ int rpcReportProgress(void *handle, char *pCont, int contLen) {
 void rpcCancelRequest(void *handle) {
   SRpcReqContext *pContext = handle;
 
-  // signature is used to check if pContext is freed. 
-  // pContext may have been released just before app calls the rpcCancelRequest 
-  if (pContext == NULL || pContext->signature != pContext) return;
+  int code = taosAcquireRef(tsRpcRefId, pContext);
+  if (code < 0) return;
 
   if (pContext->pConn) {
     tDebug("%s, app tries to cancel request", pContext->pConn->info);
     rpcCloseConn(pContext->pConn);
   }
+
+  taosReleaseRef(tsRpcRefId, pContext);
 }
 
 static void rpcFreeMsg(void *msg) {
@@ -612,7 +626,7 @@ static void rpcReleaseConn(SRpcConn *pConn) {
     // if there is an outgoing message, free it
     if (pConn->outType && pConn->pReqMsg) {
       if (pConn->pContext) pConn->pContext->pConn = NULL; 
-      rpcFreeMsg(pConn->pReqMsg);
+      taosRemoveRef(tsRpcRefId, pConn->pContext);
     }
   }
 
@@ -1068,7 +1082,6 @@ static void *rpcProcessMsgFromPeer(SRecvInfo *pRecv) {
 static void rpcNotifyClient(SRpcReqContext *pContext, SRpcMsg *pMsg) {
   SRpcInfo       *pRpc = pContext->pRpc;
 
-  pContext->signature = NULL;
   pContext->pConn = NULL;
   if (pContext->pRsp) { 
     // for synchronous API
@@ -1085,7 +1098,7 @@ static void rpcNotifyClient(SRpcReqContext *pContext, SRpcMsg *pMsg) {
   }
 
   // free the request message
-  rpcFreeCont(pContext->pCont); 
+  taosRemoveRef(tsRpcRefId, pContext); 
 }
 
 static void rpcProcessIncomingMsg(SRpcConn *pConn, SRpcHead *pHead, SRpcReqContext *pContext) {
@@ -1593,6 +1606,12 @@ static void rpcDecRef(SRpcInfo *pRpc)
     pthread_mutex_destroy(&pRpc->mutex);
     tDebug("%s rpc resources are released", pRpc->label);
     taosTFree(pRpc);
+
+    int count = atomic_sub_fetch_32(&tsRpcNum, 1);
+    if (count == 0) {
+      taosCloseRef(tsRpcRefId);
+      tsRpcInit = PTHREAD_ONCE_INIT;      
+    }
   }
 }