diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index cc3190a1d03f2423790a8de18720280b7f001329..83e8105d48d482aefb159c9bb48864432c96f8f4 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -453,7 +453,7 @@ int tscSendMsgToServer(SSqlObj *pSql) {
       .code    = 0
   };
   
-  if(rpcSendRequest(pObj->pRpcObj->pDnodeConn, &pSql->epSet, &rpcMsg, &pSql->rpcRid)) {
+  if(rpcSendRequest(pObj->pRpcObj->pDnodeConn, &pSql->epSet, &rpcMsg, &pSql->rpcRid) != BOOL_FALSE) {
     if(pSql->cmd.command == TSDB_SQL_SELECT )
       rpcSaveSendInfo(pSql->rpcRid, &pSql->pPrevContext);
     return TSDB_CODE_SUCCESS;
diff --git a/src/inc/taos.h b/src/inc/taos.h
index ea8e1d9dad61bdd513e8beded93d996ae66137dd..1a33a2910b84268f7fc0639ca436b85b6919c2f0 100644
--- a/src/inc/taos.h
+++ b/src/inc/taos.h
@@ -48,6 +48,11 @@ typedef void **TAOS_ROW;
 #define TSDB_DATA_TYPE_UBIGINT    14    // 8 bytes
 #define TSDB_DATA_TYPE_JSON       15    // json string
 
+typedef enum {
+  BOOL_FALSE = 0,
+  BOOL_TRUE  = 1,
+  BOOL_ASYNC = 2  //request is processed by async for another thread, not now true or false
+} TBOOL;
 typedef enum {
   TSDB_OPTION_LOCALE,
   TSDB_OPTION_CHARSET,
diff --git a/src/inc/trpc.h b/src/inc/trpc.h
index 52793423d7700aba9cfe51c9c5cbb8690f8621e7..b165415671ba8dfd16c07c4bb7ee5e0647008fba 100644
--- a/src/inc/trpc.h
+++ b/src/inc/trpc.h
@@ -85,7 +85,7 @@ void  rpcClose(void *);
 void *rpcMallocCont(int contLen);
 void  rpcFreeCont(void *pCont);
 void *rpcReallocCont(void *ptr, int contLen);
-bool  rpcSendRequest(void *thandle, const SRpcEpSet *pEpSet, SRpcMsg *pMsg, int64_t *rid);
+TBOOL rpcSendRequest(void *thandle, const SRpcEpSet *pEpSet, SRpcMsg *pMsg, int64_t *rid);
 void  rpcSendResponse(const SRpcMsg *pMsg);
 void  rpcSendRedirectRsp(void *pConn, const SRpcEpSet *pEpSet); 
 int   rpcGetConnInfo(void *thandle, SRpcConnInfo *pInfo);
diff --git a/src/rpc/src/rpcMain.c b/src/rpc/src/rpcMain.c
index 01c41b6e09e5e868aa680a841455486c2417dfa0..54db7f3a5990ae22f4fdc26de157280a4a4a26d1 100644
--- a/src/rpc/src/rpcMain.c
+++ b/src/rpc/src/rpcMain.c
@@ -201,7 +201,7 @@ static SRpcConn *rpcAllocateClientConn(SRpcInfo *pRpc);
 static SRpcConn *rpcAllocateServerConn(SRpcInfo *pRpc, SRecvInfo *pRecv);
 static SRpcConn *rpcGetConnObj(SRpcInfo *pRpc, int sid, SRecvInfo *pRecv);
 
-static bool  rpcSendReqToServer(SRpcInfo *pRpc, SRpcReqContext *pContext);
+static TBOOL rpcSendReqToServer(SRpcInfo *pRpc, SRpcReqContext *pContext);
 static void  rpcSendQuickRsp(SRpcConn *pConn, int32_t code);
 static void  rpcSendErrorMsgToPeer(SRecvInfo *pRecv, int32_t code);
 static bool  rpcSendMsgToPeer(SRpcConn *pConn, void *data, int dataLen);
@@ -393,7 +393,7 @@ void *rpcReallocCont(void *ptr, int contLen) {
   return start + sizeof(SRpcReqContext) + sizeof(SRpcHead);
 }
 
-bool rpcSendRequest(void *shandle, const SRpcEpSet *pEpSet, SRpcMsg *pMsg, int64_t *pRid) {
+TBOOL rpcSendRequest(void *shandle, const SRpcEpSet *pEpSet, SRpcMsg *pMsg, int64_t *pRid) {
   SRpcInfo       *pRpc = (SRpcInfo *)shandle;
   SRpcReqContext *pContext;
 
@@ -1370,7 +1370,7 @@ static void rpcSendErrorMsgToPeer(SRecvInfo *pRecv, int32_t code) {
   return; 
 }
 
-static bool rpcSendReqToServer(SRpcInfo *pRpc, SRpcReqContext *pContext) {
+static TBOOL rpcSendReqToServer(SRpcInfo *pRpc, SRpcReqContext *pContext) {
   SRpcHead  *pHead = rpcHeadFromCont(pContext->pCont);
   char      *msg = (char *)pHead;
   int        msgLen = rpcMsgLenFromCont(pContext->contLen);
@@ -1380,8 +1380,9 @@ static bool rpcSendReqToServer(SRpcInfo *pRpc, SRpcReqContext *pContext) {
   SRpcConn *pConn = rpcSetupConnToServer(pContext);
   if (pConn == NULL) {
     pContext->code = terrno;
+    // in rpcProcessConnError if numOfTry over limit, could call rpcNotifyClient to stop query
     taosTmrStart(rpcProcessConnError, 1, pContext, pRpc->tmrCtrl);
-    return false;
+    return BOOL_ASYNC;
   }
 
   pContext->pConn = pConn;
@@ -1422,7 +1423,7 @@ static bool rpcSendReqToServer(SRpcInfo *pRpc, SRpcReqContext *pContext) {
     taosTmrReset(rpcProcessRetryTimer, tsRpcTimer, pConn, pRpc->tmrCtrl, &pConn->pTimer);
 
   rpcUnlockConn(pConn);
-  return ret;
+  return ret ? BOOL_TRUE : BOOL_FALSE;
 }
 
 static bool rpcSendMsgToPeer(SRpcConn *pConn, void *msg, int msgLen) {
@@ -1464,7 +1465,6 @@ static void rpcProcessConnError(void *param, void *id) {
     return;
   }
   
-  tDebug("%s %p, connection error happens", pRpc->label, pContext->ahandle);
 
   if (pContext->numOfTry >= pContext->epSet.numOfEps || pContext->msgType == TSDB_MSG_TYPE_FETCH) {
     rpcMsg.msgType = pContext->msgType+1;
@@ -1473,9 +1473,11 @@ static void rpcProcessConnError(void *param, void *id) {
     rpcMsg.pCont = NULL;
     rpcMsg.contLen = 0;
 
+    tWarn("%s %p, connection error. notify client query over. numOfTry=%d msgType=%d", pRpc->label, pContext->ahandle, pContext->numOfTry, pContext->msgType);
     rpcNotifyClient(pContext, &rpcMsg);
   } else {
-    // move to next IP 
+    // move to next IP
+    tWarn("%s %p, connection error. retry to send request again. numOfTry=%d msgType=%d", pRpc->label, pContext->ahandle, pContext->numOfTry, pContext->msgType);
     pContext->epSet.inUse++;
     pContext->epSet.inUse = pContext->epSet.inUse % pContext->epSet.numOfEps;
     rpcSendReqToServer(pRpc, pContext);