HDFS-17232. RBF: Fix NoNamenodesAvailableException for a long time, when use observer.

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/resolver/MembershipNamenodeResolver.java

@@ -494,29 +494,31 @@ public void rotateCache(
       if (namenodeContexts == null || namenodeContexts.size() <= 1) {
         return namenodeContexts;
       }
-      FederationNamenodeContext firstNamenodeContext = namenodeContexts.get(0);
-      /*
-       * If the first nn in the cache is active, the active nn priority cannot be lowered.
-       * This happens when other threads have already updated the cache.
-       */
-      if (firstNamenodeContext.getState().equals(ACTIVE)) {
-        return namenodeContexts;
+
+      // If there is active nn, rotateCache is not needed
+      // because the router has already loaded the cache.
+      for (FederationNamenodeContext namenodeContext : namenodeContexts) {
+        if (namenodeContext.getState() == ACTIVE) {
+          return namenodeContexts;
+        }
       }
-      /*
-       * If the first nn in the cache at this time is not the nn
-       * that needs to be lowered in priority, there is no need to rotate.
-       * This happens when other threads have already rotated the cache.
-       */
-      if (firstNamenodeContext.getRpcAddress().equals(namenode.getRpcAddress())) {
-        List<FederationNamenodeContext> rotatedNnContexts = new ArrayList<>(namenodeContexts);
-        Collections.rotate(rotatedNnContexts, -1);
-        String firstNamenodeId = namenodeContexts.get(0).getNamenodeId();
-        LOG.info("Rotate cache of pair <ns: {}, observer first: {}>, put namenode: {} in the " +
-            "first position of the cache and namenode: {} in the last position of the cache",
-            nsId, listObserversFirst, firstNamenodeId, namenode.getNamenodeId());
-        return rotatedNnContexts;
+
+      // If the last namenode in the cache at this time is the namenode.
+      // No need to rotate cache, because other threads have already rotated the cache.
+      FederationNamenodeContext lastNamenode = namenodeContexts.get(namenodeContexts.size()-1);
+      if (lastNamenode.getRpcAddress().equals(namenode.getRpcAddress())) {
+        return namenodeContexts;
       }
-      return namenodeContexts;
+
+      // Move the abnormal namenode to the end of the cache,
+      // to ensure that the current namenode will not be accessed first next time.
+      List<FederationNamenodeContext> rotateNamenodeContexts =
+          (List<FederationNamenodeContext>) namenodeContexts;
+      rotateNamenodeContexts.remove(namenode);
+      rotateNamenodeContexts.add(namenode);
+      LOG.info("Rotate cache of pair<{}, {}> -> {}",
+          nsId, listObserversFirst, rotateNamenodeContexts);
+      return rotateNamenodeContexts;
     });
   }
 }

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

@@ -461,10 +461,12 @@ private static IOException toIOException(Exception e) {
    * @throws NoNamenodesAvailableException Exception that the retry policy
    *         generates for no available namenodes.
    */
-  private RetryDecision shouldRetry(final IOException ioe, final int retryCount,
-      final String nsId) throws IOException {
+  private RetryDecision shouldRetry(
+      final IOException ioe, final int retryCount, final String nsId,
+      final FederationNamenodeContext namenode,
+      final boolean listObserverFirst) throws IOException {
     // check for the case of cluster unavailable state
-    if (isClusterUnAvailable(nsId)) {
+    if (isClusterUnAvailable(nsId, namenode, listObserverFirst)) {
       // we allow to retry once if cluster is unavailable
       if (retryCount == 0) {
         return RetryDecision.RETRY;
@@ -538,7 +540,7 @@ public Object invokeMethod(
         ProxyAndInfo<?> client = connection.getClient();
         final Object proxy = client.getProxy();
 
-        ret = invoke(nsId, 0, method, proxy, params);
+        ret = invoke(nsId, namenode, useObserver, 0, method, proxy, params);
         if (failover &&
             FederationNamenodeServiceState.OBSERVER != namenode.getState()) {
           // Success on alternate server, update
@@ -594,13 +596,16 @@ public Object invokeMethod(
           se.initCause(ioe);
           throw se;
         } else if (ioe instanceof NoNamenodesAvailableException) {
+          IOException cause = (IOException) ioe.getCause();
           if (this.rpcMonitor != null) {
             this.rpcMonitor.proxyOpNoNamenodes(nsId);
           }
           LOG.error("Cannot get available namenode for {} {} error: {}",
               nsId, rpcAddress, ioe.getMessage());
           // Rotate cache so that client can retry the next namenode in the cache
-          this.namenodeResolver.rotateCache(nsId, namenode, shouldUseObserver);
+          if (shouldRotateCache(cause)) {
+            this.namenodeResolver.rotateCache(nsId, namenode, useObserver);
+          }
           // Throw RetriableException so that client can retry
           throw new RetriableException(ioe);
         } else {
@@ -708,7 +713,9 @@ private void addClientInfoToCallerContext(UserGroupInformation ugi) {
    * @return Response from the remote server
    * @throws IOException If error occurs.
    */
-  private Object invoke(String nsId, int retryCount, final Method method,
+  private Object invoke(
+      String nsId, FederationNamenodeContext namenode, Boolean listObserverFirst,
+      int retryCount, final Method method,
       final Object obj, final Object... params) throws IOException {
     try {
       return method.invoke(obj, params);
@@ -721,14 +728,14 @@ private Object invoke(String nsId, int retryCount, final Method method,
         IOException ioe = (IOException) cause;
 
         // Check if we should retry.
-        RetryDecision decision = shouldRetry(ioe, retryCount, nsId);
+        RetryDecision decision = shouldRetry(ioe, retryCount, nsId, namenode, listObserverFirst);
         if (decision == RetryDecision.RETRY) {
           if (this.rpcMonitor != null) {
             this.rpcMonitor.proxyOpRetries();
           }
 
           // retry
-          return invoke(nsId, ++retryCount, method, obj, params);
+          return invoke(nsId, namenode, listObserverFirst, ++retryCount, method, obj, params);
         } else if (decision == RetryDecision.FAILOVER_AND_RETRY) {
           // failover, invoker looks for standby exceptions for failover.
           if (ioe instanceof StandbyException) {
@@ -772,13 +779,22 @@ public static boolean isUnavailableException(IOException ioe) {
    * Check if the cluster of given nameservice id is available.
    *
    * @param nsId nameservice ID.
+   * @param namenode
+   * @param listObserverFirst
    * @return true if the cluster with given nameservice id is available.
    * @throws IOException if error occurs.
    */
-  private boolean isClusterUnAvailable(String nsId) throws IOException {
+  private boolean isClusterUnAvailable(
+      String nsId, FederationNamenodeContext namenode,
+      boolean listObserverFirst) throws IOException {
+    // Use observer and the namenode that causes the exception is an observer,
+    // false is returned so that the oberver can be marked as unavailable,so other observers
+    // or active namenode which is standby in the cache of the router can be retried.
+    if (listObserverFirst && namenode.getState() == FederationNamenodeServiceState.OBSERVER) {
+      return false;
+    }
     List<? extends FederationNamenodeContext> nnState = this.namenodeResolver
-        .getNamenodesForNameserviceId(nsId, false);
-
+        .getNamenodesForNameserviceId(nsId, listObserverFirst);
     if (nnState != null) {
       for (FederationNamenodeContext nnContext : nnState) {
         // Once we find one NN is in active state, we assume this
@@ -1830,4 +1846,24 @@ private LongAccumulator getTimeOfLastCallToActive(String namespaceId) {
     return lastActiveNNRefreshTimes
         .computeIfAbsent(namespaceId, key -> new LongAccumulator(Math::max, 0));
   }
+
+  /**
+   * Determine whether router rotated cache is required when NoNamenodesAvailableException occurs.
+   *
+   * @param ioe cause of the NoNamenodesAvailableException.
+   * @return true if NoNamenodesAvailableException occurs due to
+   * {@link RouterRpcClient#isUnavailableException(IOException) unavailable exception},
+   * otherwise false.
+   */
+  private boolean shouldRotateCache(IOException ioe) {
+    if (isUnavailableException(ioe)) {
+      return true;
+    }
+    if (ioe instanceof  RemoteException) {
+      RemoteException re = (RemoteException) ioe;
+      ioe = re.unwrapRemoteException();
+      ioe = getCleanException(ioe);
+    }
+    return isUnavailableException(ioe);
+  }
 }

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

@@ -132,9 +132,9 @@ public class MiniRouterDFSCluster {
   /** Mini cluster. */
   private MiniDFSCluster cluster;
 
-  protected static final long DEFAULT_HEARTBEAT_INTERVAL_MS =
+  public static final long DEFAULT_HEARTBEAT_INTERVAL_MS =
       TimeUnit.SECONDS.toMillis(5);
-  protected static final long DEFAULT_CACHE_INTERVAL_MS =
+  public static final long DEFAULT_CACHE_INTERVAL_MS =
       TimeUnit.SECONDS.toMillis(5);
   /** Heartbeat interval in milliseconds. */
   private long heartbeatInterval;
@@ -253,6 +253,19 @@ public FileSystem getFileSystemWithObserverReadProxyProvider() throws IOExceptio
       return DistributedFileSystem.get(observerReadConf);
     }
 
+    public FileSystem getFileSystemWithConfiguredFailoverProxyProvider() throws IOException {
+      conf.set(DFS_NAMESERVICES,
+          conf.get(DFS_NAMESERVICES)+ ",router-service");
+      conf.set(DFS_HA_NAMENODES_KEY_PREFIX + ".router-service", "router1");
+      conf.set(DFS_NAMENODE_RPC_ADDRESS_KEY+ ".router-service.router1",
+          getFileSystemURI().toString());
+      conf.set(HdfsClientConfigKeys.Failover.PROXY_PROVIDER_KEY_PREFIX
+          + "." + "router-service", ConfiguredFailoverProxyProvider.class.getName());
+      DistributedFileSystem.setDefaultUri(conf, "hdfs://router-service");
+
+      return DistributedFileSystem.get(conf);
+    }
+
     public DFSClient getClient(UserGroupInformation user)
         throws IOException, URISyntaxException, InterruptedException {