Merge branch 'trunk' into YARN-11332

slfan1989 · web-flow · commit 09a9fba13663 · 2022-10-21T00:58:38.000+08:00
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DistributedFileSystem.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DistributedFileSystem.java
@@ -568,7 +568,7 @@ public FSDataOutputStream next(final FileSystem fs, final Path p)
 
   /**
    * Same as
-   * {@link #create(Path, FsPermission, EnumSet<CreateFlag>, int, short, long,
+   * {@link #create(Path, FsPermission, EnumSet, int, short, long,
    * Progressable, ChecksumOpt)} with a few additions. First, addition of
    * favoredNodes that is a hint to where the namenode should place the file
    * blocks. The favored nodes hint is not persisted in HDFS. Hence it may be
@@ -637,12 +637,12 @@ protected HdfsDataOutputStream primitiveCreate(Path f,
 
   /**
    * Similar to {@link #create(Path, FsPermission, EnumSet, int, short, long,
-   * Progressable, ChecksumOpt, InetSocketAddress[], String)}, it provides a
+   * Progressable, ChecksumOpt, InetSocketAddress[], String, String)}, it provides a
    * HDFS-specific version of {@link #createNonRecursive(Path, FsPermission,
    * EnumSet, int, short, long, Progressable)} with a few additions.
    *
    * @see #create(Path, FsPermission, EnumSet, int, short, long, Progressable,
-   * ChecksumOpt, InetSocketAddress[], String) for the descriptions of
+   * ChecksumOpt, InetSocketAddress[], String, String) for the descriptions of
    * additional parameters, i.e., favoredNodes, ecPolicyName and
    * storagePolicyName.
    */
diff --git a/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/CreateEncryptionZoneFlag.java b/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/CreateEncryptionZoneFlag.java
@@ -19,6 +19,9 @@
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.fs.Path;
+
+import java.util.EnumSet;
 
 /**
  * CreateEncryptionZoneFlag is used in
diff --git a/hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RemoteMethod.java b/hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RemoteMethod.java
@@ -131,7 +131,7 @@ public Class<?> getProtocol() {
   /**
    * Get the represented java method.
    *
-   * @return Method
+   * @return {@link Method}
    * @throws IOException If the method cannot be found.
    */
   public Method getMethod() throws IOException {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/qjournal/client/AsyncLoggerSet.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/qjournal/client/AsyncLoggerSet.java
@@ -87,7 +87,7 @@ boolean isEpochEstablished() {
   
   /**
    * @return the epoch number for this writer. This may only be called after
-   * a successful call to {@link #createNewUniqueEpoch(NamespaceInfo)}.
+   * a successful call to {@link QuorumJournalManager#createNewUniqueEpoch()}.
    */
   long getEpoch() {
     Preconditions.checkState(myEpoch != INVALID_EPOCH,
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataStorage.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataStorage.java
@@ -1403,7 +1403,7 @@ public boolean accept(File dir, String name) {
   }
 
   /**
-   * Get the BlockPoolSliceStorage from {@link bpStorageMap}.
+   * Get the BlockPoolSliceStorage from {@link #bpStorageMap}.
    * If the object is not found, create a new object and put it to the map.
    */
   synchronized BlockPoolSliceStorage getBlockPoolSliceStorage(
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/checker/ThrottledAsyncChecker.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/checker/ThrottledAsyncChecker.java
@@ -44,14 +44,14 @@
 
 /**
  * An implementation of {@link AsyncChecker} that skips checking recently
- * checked objects. It will enforce at least {@link minMsBetweenChecks}
+ * checked objects. It will enforce at least {@link #minMsBetweenChecks}
  * milliseconds between two successive checks of any one object.
  *
  * It is assumed that the total number of Checkable objects in the system
  * is small, (not more than a few dozen) since the checker uses O(Checkables)
  * storage and also potentially O(Checkables) threads.
  *
- * {@link minMsBetweenChecks} should be configured reasonably
+ * {@link #minMsBetweenChecks} should be configured reasonably
  * by the caller to avoid spinning up too many threads frequently.
  */
 @InterfaceAudience.Private
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/checker/TimeoutFuture.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/checker/TimeoutFuture.java
@@ -31,6 +31,7 @@
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import java.util.concurrent.ExecutionException;
 
 /**
  * Implementation of {@code Futures#withTimeout}.
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/RamDiskReplicaTracker.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/RamDiskReplicaTracker.java
@@ -184,7 +184,7 @@ public long getLockedBytesReserved() {
    * {@link org.apache.hadoop.hdfs.DFSConfigKeys#DFS_DATANODE_RAM_DISK_REPLICA_TRACKER_KEY}.
    *
    * @param conf the configuration to be used
-   * @param dataset the FsDataset object.
+   * @param fsDataset the FsDataset object.
    * @return an instance of RamDiskReplicaTracker
    */
   static RamDiskReplicaTracker getInstance(final Configuration conf,
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirRenameOp.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirRenameOp.java
@@ -152,8 +152,8 @@ private static INodesInPath dstForRenameTo(
    * @param srcIIP source path
    * @param dstIIP destination path
    * @return true INodesInPath if rename succeeds; null otherwise
-   * @deprecated See {@link #renameToInt(FSDirectory, String, String,
-   * boolean, Options.Rename...)}
+   * @deprecated See {@link #renameToInt(FSDirectory, FSPermissionChecker,
+   * String, String, boolean, Options.Rename...)}
    */
   @Deprecated
   static INodesInPath unprotectedRenameTo(FSDirectory fsd,
@@ -258,8 +258,8 @@ static RenameResult renameToInt(
   }
 
   /**
-   * @see {@link #unprotectedRenameTo(FSDirectory, String, String, INodesInPath,
-   * INodesInPath, long, BlocksMapUpdateInfo, Options.Rename...)}
+   * @see {@link #unprotectedRenameTo(FSDirectory, INodesInPath, INodesInPath,
+   * long, BlocksMapUpdateInfo, Options.Rename...)}
    */
   static RenameResult renameTo(FSDirectory fsd, FSPermissionChecker pc,
       String src, String dst, BlocksMapUpdateInfo collectedBlocks,
@@ -482,8 +482,8 @@ static RenameResult unprotectedRenameTo(FSDirectory fsd,
   }
 
   /**
-   * @deprecated Use {@link #renameToInt(FSDirectory, String, String,
-   * boolean, Options.Rename...)}
+   * @deprecated Use {@link #renameToInt(FSDirectory, FSPermissionChecker,
+   * String, String, boolean, Options.Rename...)}
    */
   @Deprecated
   private static RenameResult renameTo(FSDirectory fsd, FSPermissionChecker pc,
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/EditLogTailer.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/EditLogTailer.java
@@ -123,7 +123,7 @@ public class EditLogTailer {
 
   /**
    * The timeout in milliseconds of calling rollEdits RPC to Active NN.
-   * @see HDFS-4176.
+   * See HDFS-4176.
    */
   private final long rollEditsTimeoutMs;
 
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/SnapshotFSImageFormat.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/snapshot/SnapshotFSImageFormat.java
@@ -70,7 +70,7 @@ public static void saveSnapshots(INodeDirectory current, DataOutput out)
 
   /**
    * Save SnapshotDiff list for an INodeDirectoryWithSnapshot.
-   * @param sNode The directory that the SnapshotDiff list belongs to.
+   * @param diffs The directory that the SnapshotDiff list belongs to.
    * @param out The {@link DataOutput} to write.
    */
   private static <N extends INode, A extends INodeAttributes, D extends AbstractINodeDiff<N, A, D>>
@@ -186,7 +186,7 @@ private static List<INode> loadCreatedList(INodeDirectory parent,
    * @param createdList The created list associated with the deleted list in 
    *                    the same Diff.
    * @param in The {@link DataInput} to read.
-   * @param loader The {@link Loader} instance.
+   * @param loader The {@link FSImageFormat.Loader} instance.
    * @return The deleted list.
    */
   private static List<INode> loadDeletedList(INodeDirectory parent,
@@ -260,7 +260,7 @@ public static void loadDirectoryDiffList(INodeDirectory dir,
    * Load the snapshotINode field of {@link AbstractINodeDiff}.
    * @param snapshot The Snapshot associated with the {@link AbstractINodeDiff}.
    * @param in The {@link DataInput} to read.
-   * @param loader The {@link Loader} instance that this loading procedure is
+   * @param loader The {@link FSImageFormat.Loader} instance that this loading procedure is
    *               using.
    * @return The snapshotINode.
    */
@@ -281,7 +281,7 @@ private static INodeDirectoryAttributes loadSnapshotINodeInDirectoryDiff(
    * Load {@link DirectoryDiff} from fsimage.
    * @param parent The directory that the SnapshotDiff belongs to.
    * @param in The {@link DataInput} instance to read.
-   * @param loader The {@link Loader} instance that this loading procedure is 
+   * @param loader The {@link FSImageFormat.Loader} instance that this loading procedure is
    *               using.
    * @return A {@link DirectoryDiff}.
    */
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/PBImageTextWriter.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/PBImageTextWriter.java
@@ -85,7 +85,7 @@
 /**
  * This class reads the protobuf-based fsimage and generates text output
  * for each inode to {@link PBImageTextWriter#out}. The sub-class can override
- * {@link getEntry()} to generate formatted string for each inode.
+ * {@link #getEntry(String, INode)} to generate formatted string for each inode.
  *
  * Since protobuf-based fsimage does not guarantee the order of inodes and
  * directories, PBImageTextWriter runs two-phase scans:
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/util/MD5FileUtils.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/util/MD5FileUtils.java
@@ -68,7 +68,7 @@ public static void verifySavedMD5(File dataFile, MD5Hash expectedMD5)
   /**
    * Read the md5 file stored alongside the given data file
    * and match the md5 file content.
-   * @param dataFile the file containing data
+   * @param md5File the file containing md5 data
    * @return a matcher with two matched groups
    *   where group(1) is the md5 string and group(2) is the data file path.
    */
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/conf/YarnConfiguration.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-api/src/main/java/org/apache/hadoop/yarn/conf/YarnConfiguration.java
@@ -4117,6 +4117,14 @@ public static boolean isAclEnabled(Configuration conf) {
       ROUTER_PREFIX + "submit.retry";
   public static final int DEFAULT_ROUTER_CLIENTRM_SUBMIT_RETRY = 3;
 
+  /**
+   * GetNewApplication and SubmitApplication request retry interval time.
+   */
+  public static final String ROUTER_CLIENTRM_SUBMIT_INTERVAL_TIME =
+      ROUTER_PREFIX + "submit.interval.time";
+  public static final long DEFAULT_CLIENTRM_SUBMIT_INTERVAL_TIME =
+      TimeUnit.MILLISECONDS.toMillis(10);
+
   /**
    * The interceptor class used in FederationClientInterceptor should return
    * partial ApplicationReports.
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/resources/yarn-default.xml b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/resources/yarn-default.xml
@@ -5074,6 +5074,15 @@
       This configurable is used to set the keepAliveTime of the thread pool of the interceptor.
       Default is 0s.
     </description>
+  </property>   
+ 
+  <property>
+    <name>yarn.router.submit.interval.time</name>
+    <value>10ms</value>
+    <description>
+      The interval Time between calling different subCluster requests.
+      Default is 10ms.
+    </description>
   </property>
 
 </configuration>
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/src/main/java/org/apache/hadoop/yarn/server/federation/retry/FederationActionRetry.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/src/main/java/org/apache/hadoop/yarn/server/federation/retry/FederationActionRetry.java
@@ -24,13 +24,13 @@ public interface FederationActionRetry<T> {
 
   Logger LOG = LoggerFactory.getLogger(FederationActionRetry.class);
 
-  T run() throws Exception;
+  T run(int retry) throws Exception;
 
   default T runWithRetries(int retryCount, long retrySleepTime) throws Exception {
     int retry = 0;
     while (true) {
       try {
-        return run();
+        return run(retry);
       } catch (Exception e) {
         LOG.info("Exception while executing an Federation operation.", e);
         if (++retry > retryCount) {
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/federation/FederationStateStoreService.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/federation/FederationStateStoreService.java
@@ -502,11 +502,11 @@ public boolean cleanUpFinishApplicationsWithRetries(ApplicationId appId, boolean
       throws Exception {
 
     // Generate a request to delete data
-    DeleteApplicationHomeSubClusterRequest request =
+    DeleteApplicationHomeSubClusterRequest req =
         DeleteApplicationHomeSubClusterRequest.newInstance(appId);
 
     // CleanUp Finish App.
-    return ((FederationActionRetry<Boolean>) () -> invokeCleanUpFinishApp(appId, isQuery, request))
+    return ((FederationActionRetry<Boolean>) (retry) -> invokeCleanUpFinishApp(appId, isQuery, req))
         .runWithRetries(cleanUpRetryCountNum, cleanUpRetrySleepTime);
   }
 
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/main/java/org/apache/hadoop/yarn/server/router/RouterAuditLogger.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/main/java/org/apache/hadoop/yarn/server/router/RouterAuditLogger.java
@@ -196,6 +196,24 @@ public static void logFailure(String user, String operation, String perm,
     }
   }
 
+  /**
+   * Create a readable and parsable audit log string for a failed event.
+   *
+   * @param user User who made the service request.
+   * @param operation Operation requested by the user.
+   * @param perm Target permissions.
+   * @param target The target on which the operation is being performed.
+   * @param description Some additional information as to why the operation failed.
+   * @param subClusterId SubCluster Id in which operation was performed.
+   */
+  public static void logFailure(String user, String operation, String perm,
+      String target, String description, SubClusterId subClusterId) {
+    if (LOG.isInfoEnabled()) {
+      LOG.info(createFailureLog(user, operation, perm, target, description, null,
+          subClusterId));
+    }
+  }
+
   /**
    * A helper api for creating an audit log for a failure event.
    */
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/main/java/org/apache/hadoop/yarn/server/router/RouterServerUtil.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/main/java/org/apache/hadoop/yarn/server/router/RouterServerUtil.java
@@ -18,6 +18,8 @@
 
 package org.apache.hadoop.yarn.server.router;
 
+import org.apache.commons.collections.CollectionUtils;
+import org.apache.commons.collections.MapUtils;
 import org.apache.commons.lang3.math.NumberUtils;
 import org.apache.hadoop.classification.InterfaceAudience.Private;
 import org.apache.hadoop.classification.InterfaceAudience.Public;
@@ -27,6 +29,9 @@
 import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.yarn.exceptions.YarnException;
 import org.apache.hadoop.yarn.exceptions.YarnRuntimeException;
+import org.apache.hadoop.yarn.server.federation.policies.FederationPolicyUtils;
+import org.apache.hadoop.yarn.server.federation.store.records.SubClusterId;
+import org.apache.hadoop.yarn.server.federation.store.records.SubClusterInfo;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -35,6 +40,8 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
+import java.util.Map;
+import java.util.Random;
 import java.io.IOException;
 
 /**
@@ -53,6 +60,8 @@ public final class RouterServerUtil {
 
   private static final String EPOCH_PREFIX = "e";
 
+  private static Random rand = new Random(System.currentTimeMillis());
+
   /** Disable constructor. */
   private RouterServerUtil() {
   }
@@ -446,4 +455,40 @@ public static void validateContainerId(String containerId)
       throw new IllegalArgumentException("Invalid ContainerId: " + containerId);
     }
   }
+
+  /**
+   * Randomly pick ActiveSubCluster.
+   * During the selection process, we will exclude SubClusters from the blacklist.
+   *
+   * @param activeSubClusters List of active subClusters.
+   * @param blackList blacklist.
+   * @return Active SubClusterId.
+   * @throws YarnException When there is no Active SubCluster,
+   * an exception will be thrown (No active SubCluster available to submit the request.)
+   */
+  public static SubClusterId getRandomActiveSubCluster(
+      Map<SubClusterId, SubClusterInfo> activeSubClusters, List<SubClusterId> blackList)
+      throws YarnException {
+
+    // Check if activeSubClusters is empty, if it is empty, we need to throw an exception
+    if (MapUtils.isEmpty(activeSubClusters)) {
+      logAndThrowException(FederationPolicyUtils.NO_ACTIVE_SUBCLUSTER_AVAILABLE, null);
+    }
+
+    // Change activeSubClusters to List
+    List<SubClusterId> subClusterIds = new ArrayList<>(activeSubClusters.keySet());
+
+    // If the blacklist is not empty, we need to remove all the subClusters in the blacklist
+    if (CollectionUtils.isNotEmpty(blackList)) {
+      subClusterIds.removeAll(blackList);
+    }
+
+    // Check there are still active subcluster after removing the blacklist
+    if (CollectionUtils.isEmpty(subClusterIds)) {
+      logAndThrowException(FederationPolicyUtils.NO_ACTIVE_SUBCLUSTER_AVAILABLE, null);
+    }
+
+    // Randomly choose a SubCluster
+    return subClusterIds.get(rand.nextInt(subClusterIds.size()));
+  }
 }
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/main/java/org/apache/hadoop/yarn/server/router/clientrm/FederationClientInterceptor.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/main/java/org/apache/hadoop/yarn/server/router/clientrm/FederationClientInterceptor.java
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/test/java/org/apache/hadoop/yarn/server/router/clientrm/TestFederationClientInterceptorRetry.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/test/java/org/apache/hadoop/yarn/server/router/clientrm/TestFederationClientInterceptorRetry.java
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/Federation.md b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/Federation.md

Original file line number	Diff line number	Diff line change
`@@ -131,7 +131,7 @@ public Class<?> getProtocol() {`
`131`	`131`	`/**`
`132`	`132`	`* Get the represented java method.`
`133`	`133`	`*`
`134`		`- * @return Method`
	`134`	`+ * @return {@link Method}`
`135`	`135`	`* @throws IOException If the method cannot be found.`
`136`	`136`	`*/`
`137`	`137`	`public Method getMethod() throws IOException {`
Original file line number	Diff line number	Diff line change
`@@ -1403,7 +1403,7 @@ public boolean accept(File dir, String name) {`
`1403`	`1403`	`}`
`1404`	`1404`
`1405`	`1405`	`/**`
`1406`		`- * Get the BlockPoolSliceStorage from {@link bpStorageMap}.`
	`1406`	`+ * Get the BlockPoolSliceStorage from {@link #bpStorageMap}.`
`1407`	`1407`	`* If the object is not found, create a new object and put it to the map.`
`1408`	`1408`	`*/`
`1409`	`1409`	`synchronized BlockPoolSliceStorage getBlockPoolSliceStorage(`
Original file line number	Diff line number	Diff line change
`@@ -184,7 +184,7 @@ public long getLockedBytesReserved() {`
`184`	`184`	`* {@link org.apache.hadoop.hdfs.DFSConfigKeys#DFS_DATANODE_RAM_DISK_REPLICA_TRACKER_KEY}.`
`185`	`185`	`*`
`186`	`186`	`* @param conf the configuration to be used`
`187`		`- * @param dataset the FsDataset object.`
	`187`	`+ * @param fsDataset the FsDataset object.`
`188`	`188`	`* @return an instance of RamDiskReplicaTracker`
`189`	`189`	`*/`
`190`	`190`	`static RamDiskReplicaTracker getInstance(final Configuration conf,`