fix some failed unit tests.

Author: hfutatzhanghb

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterRpcClient.java

@@ -25,6 +25,8 @@
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_IP_PROXY_USERS;
 import static org.apache.hadoop.hdfs.server.federation.fairness.RouterRpcFairnessConstants.CONCURRENT_NS;
 import static org.apache.hadoop.hdfs.server.federation.metrics.FederationRPCPerformanceMonitor.CONCURRENT;
+import static org.apache.hadoop.hdfs.server.federation.router.RBFConfigKeys.DFS_ROUTER_ASYNC_RPC_ENABLE_DEFAULT;
+import static org.apache.hadoop.hdfs.server.federation.router.RBFConfigKeys.DFS_ROUTER_ASYNC_RPC_ENABLE_KEY;
 
 import java.io.EOFException;
 import java.io.FileNotFoundException;
@@ -200,7 +202,7 @@ public RouterRpcClient(Configuration conf, Router router,
       workQueue = new LinkedBlockingQueue<>();
     }
 
-    if (router.getRpcServer().isAsync()) {
+    if (isAsync()) {
       this.executorService = null;
     } else {
       this.executorService = new ThreadPoolExecutor(numThreads, numThreads,
@@ -2033,6 +2035,13 @@ protected boolean shouldRotateCache(IOException ioe) {
     }
     return isUnavailableException(ioe);
   }
+  
+  @VisibleForTesting
+  private boolean isAsync() {
+    return router.getRpcServer() != null ? router.getRpcServer().isAsync() :
+        router.getConfig().getBoolean(DFS_ROUTER_ASYNC_RPC_ENABLE_KEY,
+            DFS_ROUTER_ASYNC_RPC_ENABLE_DEFAULT);
+  }
 
 
   /**