HDFS-15952. TestRouterRpcMultiDestination#testProxyGetTransactionID and testProxyVersionRequest are flaky. (#2970)

hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/router/TestRouterRpc.java

@@ -26,6 +26,7 @@ import static org.apache.hadoop.hdfs.server.federation.FederationTestUtils.getFi
 import static org.apache.hadoop.hdfs.server.federation.FederationTestUtils.verifyFileExists;
 import static org.apache.hadoop.hdfs.server.federation.MiniRouterDFSCluster.TEST_STRING;
 import static org.apache.hadoop.test.GenericTestUtils.assertExceptionContains;
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -185,6 +186,7 @@ public class TestRouterRpc {
   private NamenodeProtocol routerNamenodeProtocol;
   /** NameNodeProtocol interface to the Namenode. */
   private NamenodeProtocol nnNamenodeProtocol;
+  private NamenodeProtocol nnNamenodeProtocol1;
 
   /** Filesystem interface to the Router. */
   private FileSystem routerFS;
@@ -366,6 +368,11 @@ public class TestRouterRpc {
     NamenodeContext nn0 = cluster.getNamenode(ns0, null);
     this.nnNamenodeProtocol = NameNodeProxies.createProxy(nn0.getConf(),
         nn0.getFileSystem().getUri(), NamenodeProtocol.class).getProxy();
+    // Namenode from the other namespace
+    String ns1 = cluster.getNameservices().get(1);
+    NamenodeContext nn1 = cluster.getNamenode(ns1, null);
+    this.nnNamenodeProtocol1 = NameNodeProxies.createProxy(nn1.getConf(),
+        nn1.getFileSystem().getUri(), NamenodeProtocol.class).getProxy();
   }
 
   protected String getNs() {
@@ -1302,11 +1309,14 @@ public class TestRouterRpc {
       // Check with default namespace specified.
       NamespaceInfo rVersion = routerNamenodeProtocol.versionRequest();
       NamespaceInfo nnVersion = nnNamenodeProtocol.versionRequest();
+      NamespaceInfo nnVersion1 = nnNamenodeProtocol1.versionRequest();
       compareVersion(rVersion, nnVersion);
       // Check with default namespace unspecified.
       resolver.setDisableNamespace(true);
-      rVersion = routerNamenodeProtocol.versionRequest();
-      compareVersion(rVersion, nnVersion);
+      // Verify the NamespaceInfo is of nn0 or nn1
+      boolean isNN0 =
+          rVersion.getBlockPoolID().equals(nnVersion.getBlockPoolID());
+      compareVersion(rVersion, isNN0 ? nnVersion : nnVersion1);
     } finally {
       resolver.setDisableNamespace(false);
     }
@@ -1375,11 +1385,13 @@ public class TestRouterRpc {
       // Check with default namespace specified.
       long routerTransactionID = routerNamenodeProtocol.getTransactionID();
       long nnTransactionID = nnNamenodeProtocol.getTransactionID();
+      long nnTransactionID1 = nnNamenodeProtocol1.getTransactionID();
       assertEquals(nnTransactionID, routerTransactionID);
       // Check with default namespace unspecified.
       resolver.setDisableNamespace(true);
+      // Verify the transaction ID is of nn0 or nn1
       routerTransactionID = routerNamenodeProtocol.getTransactionID();
-      assertEquals(nnTransactionID, routerTransactionID);
+      assertThat(routerTransactionID).isIn(nnTransactionID, nnTransactionID1);
     } finally {
       resolver.setDisableNamespace(false);
     }