setMaxTotalConnections 100 (#25)

* setMaxTotalConnections 1000

* setMaxTotalConnections 100

Author: lipanpan03

rpc-client/src/main/java/com/antgroup/tugraph/TuGraphDbRpcClient.java

@@ -363,6 +363,7 @@ private static class TuGraphSingleRpcClient {
 
         public TuGraphSingleRpcClient(String url, String user, String pass) {
             RpcClientOptions options = new RpcClientOptions();
+            options.setMaxTotalConnections(100);
             options.setProtocolType(Options.ProtocolType.PROTOCOL_BAIDU_STD_VALUE);
             options.setLoadBalanceType(LoadBalanceStrategy.LOAD_BALANCE_FAIR);
             options.setWriteTimeoutMillis(TIMEOUTINMS);