diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index c6e9cbafd751809e6bfdedb064f3b6c40480699b..ddbee3106d890abdc18db907d43c3a528ecba286 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -188,8 +188,8 @@ void tscProcessActivityTimer(void *handle, void *tmrId) {
 
   if (tscShouldFreeHeartBeat(pHB)) {
     tscDebug("%p free HB object and release connection", pHB);
-    tscFreeSqlObj(pHB);
-    tscCloseTscObj(pObj);
+    pObj->pHb = 0;
+    taos_free_result(pHB);
   } else {
     int32_t code = tscProcessSql(pHB);
     if (code != TSDB_CODE_SUCCESS) {
@@ -1959,6 +1959,7 @@ int tscProcessShowRsp(SSqlObj *pSql) {
   return 0;
 }
 
+// TODO multithread problem
 static void createHBObj(STscObj* pObj) {
   if (pObj->pHb != NULL) {
     return;
@@ -1987,10 +1988,13 @@ static void createHBObj(STscObj* pObj) {
   pSql->pTscObj = pObj;
   pSql->signature = pSql;
   pObj->pHb = pSql;
-  T_REF_INC(pObj);
 
   tscAddSubqueryInfo(&pObj->pHb->cmd);
 
+  int64_t ad = (int64_t) pSql;
+  pSql->self = taosCachePut(tscObjCache, &ad, sizeof(int64_t), &pSql, sizeof(int64_t), 2 * 60 * 1000);
+  T_REF_INC(pObj);
+
   tscDebug("%p HB is allocated, pObj:%p", pObj->pHb, pObj);
 }
 
@@ -2017,8 +2021,7 @@ int tscProcessConnectRsp(SSqlObj *pSql) {
   pObj->connId = htonl(pConnect->connId);
 
   createHBObj(pObj);
-
-//  taosTmrReset(tscProcessActivityTimer, tsShellActivityTimer * 500, pObj, tscTmr, &pObj->pTimer);
+  taosTmrReset(tscProcessActivityTimer, tsShellActivityTimer * 500, pObj, tscTmr, &pObj->pTimer);
 
   return 0;
 }
diff --git a/src/client/src/tscSql.c b/src/client/src/tscSql.c
index 1df77d18503604637f16e7e620e59b327a62d5d9..598ec7e5469c87cacb7e845ebcfa6a8bf5937ea8 100644
--- a/src/client/src/tscSql.c
+++ b/src/client/src/tscSql.c
@@ -263,32 +263,15 @@ void taos_close(TAOS *taos) {
     return;
   }
 
-  if (pObj->pHb != NULL) {
-    if (pObj->pHb->pRpcCtx != NULL) {  // wait for rsp from dnode
-      rpcCancelRequest(pObj->pHb->pRpcCtx);
+  SSqlObj* pHb = pObj->pHb;
+  if (pHb != NULL) {
+    if (pHb->pRpcCtx != NULL) {  // wait for rsp from dnode
+      rpcCancelRequest(pHb->pRpcCtx);
     }
 
-    tscSetFreeHeatBeat(pObj);
-    tscFreeSqlObj(pObj->pHb);
-  }
-
-  // free all sqlObjs created by using this connect before free the STscObj
-//  while(1) {
-//    pthread_mutex_lock(&pObj->mutex);
-//    void* p = pObj->sqlList;
-//    pthread_mutex_unlock(&pObj->mutex);
-//
-//    if (p == NULL) {
-//      break;
-//    }
-//
-//    tscDebug("%p waiting for sqlObj to be freed, %p", pObj, p);
-//    taosMsleep(100);
-//
-//    // todo fix me!! two threads call taos_free_result will cause problem.
-//    tscDebug("%p free :%p", pObj, p);
-//    taos_free_result(p);
-//  }
+    pObj->pHb = NULL;
+    taos_free_result(pHb);
+  }
 
   int32_t ref = T_REF_DEC(pObj);
   assert(ref >= 0);
diff --git a/src/rpc/src/rpcMain.c b/src/rpc/src/rpcMain.c
index f59bf62ec504444c561107bb5b5dcf3ec6f8c000..cb318d5c24f26e66e2771c170ac39010e6e34ca0 100644
--- a/src/rpc/src/rpcMain.c
+++ b/src/rpc/src/rpcMain.c
@@ -580,6 +580,8 @@ static SRpcConn *rpcOpenConn(SRpcInfo *pRpc, char *peerFqdn, uint16_t peerPort,
       void *shandle = (connType & RPC_CONN_TCP)? pRpc->tcphandle:pRpc->udphandle;
       pConn->chandle = (*taosOpenConn[connType])(shandle, pConn, pConn->peerIp, pConn->peerPort);
       if (pConn->chandle == NULL) {
+        tError("failed to connect to:0x%x:%d", pConn->peerIp, pConn->peerPort);
+
         terrno = TSDB_CODE_RPC_NETWORK_UNAVAIL;
         rpcCloseConn(pConn);
         pConn = NULL;
diff --git a/src/util/src/tcache.c b/src/util/src/tcache.c
index 4d737ebe66f1e82614d4eb71c1d93129949c5c4e..e1dd521547f3cc14e6715b07e6c28a50d0cf105a 100644
--- a/src/util/src/tcache.c
+++ b/src/util/src/tcache.c
@@ -260,7 +260,13 @@ static void incRefFn(void* ptNode) {
 }
 
 void *taosCacheAcquireByKey(SCacheObj *pCacheObj, const void *key, size_t keyLen) {
-  if (pCacheObj == NULL || taosHashGetSize(pCacheObj->pHashTable) == 0 || pCacheObj->deleting == 1) {
+  if (pCacheObj == NULL || pCacheObj->deleting == 1) {
+    return NULL;
+  }
+
+  if (taosHashGetSize(pCacheObj->pHashTable) == 0) {
+    atomic_add_fetch_32(&pCacheObj->statistics.missCount, 1);
+    uError("cache:%s, key:%p, not in cache, retrieved failed, reason: empty sqlObj cache", pCacheObj->name, key);
     return NULL;
   }
 
@@ -274,7 +280,7 @@ void *taosCacheAcquireByKey(SCacheObj *pCacheObj, const void *key, size_t keyLen
     uDebug("cache:%s, key:%p, %p is retrieved from cache, refcnt:%d", pCacheObj->name, key, pData, T_REF_VAL_GET(ptNode));
   } else {
     atomic_add_fetch_32(&pCacheObj->statistics.missCount, 1);
-    uDebug("cache:%s, key:%p, not in cache, retrieved failed", pCacheObj->name, key);
+    uError("cache:%s, key:%p, not in cache, retrieved failed", pCacheObj->name, key);
   }
 
   atomic_add_fetch_32(&pCacheObj->statistics.totalAccess, 1);