[TS-1383]<fix>(common): Add configurable option of tcpConnTimeout.

src/common/src/tglobal.c

@@ -48,6 +48,7 @@ char     tsEmail[TSDB_FQDN_LEN] = {0};
 int32_t  tsDnodeId = 0;
 int64_t  tsDnodeStartTime = 0;
 int8_t   tsDnodeNopLoop = 0;
+int32_t  tsTcpConnTimeout = 1; // timeout for tcp client connection in second.
 
 // common
 int32_t tsRpcTimer = 300;
@@ -635,6 +636,16 @@ static void doInitGlobalConfig(void) {
   cfg.unitType = TAOS_CFG_UTYPE_NONE;
   taosInitConfigOption(cfg);
 
+  cfg.option = "tcpConnTimeout";
+  cfg.ptr = &tsTcpConnTimeout;
+  cfg.valType = TAOS_CFG_VTYPE_INT32;
+  cfg.cfgType = TSDB_CFG_CTYPE_B_CONFIG | TSDB_CFG_CTYPE_B_SHOW;
+  cfg.minValue = 1;
+  cfg.maxValue = 10;
+  cfg.ptrLength = 0;
+  cfg.unitType = TAOS_CFG_UTYPE_SECOND;
+  taosInitConfigOption(cfg);
+
   cfg.option = "balance";
   cfg.ptr = &tsEnableBalance;
   cfg.valType = TAOS_CFG_VTYPE_INT8;

src/util/src/tsocket.c

@@ -362,7 +362,7 @@ SOCKET taosOpenTcpClientSocket(uint32_t destIp, uint16_t destPort, uint32_t clie
       wfd[0].fd = sockFd;
       wfd[0].events = POLLOUT;
     
-      int res = poll(wfd, 1, TCP_CONN_TIMEOUT);
+      int res = poll(wfd, 1, tsTcpConnTimeout * 1000);
       if (res == -1 || res == 0) {
         uError("failed to connect socket, ip:0x%x, port:%hu(poll error/conn timeout)", destIp, destPort);
         taosCloseSocket(sockFd); //