HDDS-10452. Improve Recon Disk Usage to fetch and display Top N records based on size.

hadoop-ozone/recon/src/main/java/org/apache/hadoop/ozone/recon/ReconConstants.java

@@ -36,6 +36,11 @@ private ReconConstants() {
   public static final String RECON_SCM_SNAPSHOT_DB = "scm.snapshot.db";
 
   // By default, limit the number of results returned
+
+  /**
+   * The maximum number of top disk usage records to return in a /du response.
+   */
+  public static final int DISK_USAGE_TOP_RECORDS_LIMIT = 30;
   public static final String DEFAULT_OPEN_KEY_INCLUDE_NON_FSO = "false";
   public static final String DEFAULT_OPEN_KEY_INCLUDE_FSO = "false";
   public static final String DEFAULT_FETCH_COUNT = "1000";

hadoop-ozone/recon/src/main/java/org/apache/hadoop/ozone/recon/ReconUtils.java

@@ -32,6 +32,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.BlockingQueue;
+import java.util.stream.Collectors;
 
 import com.google.common.base.Preconditions;
 import com.google.inject.Singleton;
@@ -59,6 +60,7 @@
 import static org.jooq.impl.DSL.select;
 import static org.jooq.impl.DSL.using;
 
+import org.apache.hadoop.ozone.recon.api.types.DUResponse;
 import org.apache.hadoop.ozone.recon.scm.ReconContainerReportQueue;
 import org.apache.hadoop.security.authentication.client.AuthenticationException;
 import org.hadoop.ozone.recon.schema.tables.daos.GlobalStatsDao;
@@ -322,6 +324,33 @@ public static void upsertGlobalStatsTable(Configuration sqlConfiguration,
     }
   }
 
+  /**
+   * Sorts a list of DiskUsage objects in descending order by size using parallel sorting and
+   * returns the top N records as specified by the limit.
+   *
+   * This method is optimized for large datasets and utilizes parallel processing to efficiently
+   * sort and retrieve the top N largest records by size. It's especially useful for reducing
+   * processing time and memory usage when only a subset of sorted records is needed.
+   *
+   * Advantages of this approach include:
+   * - Efficient handling of large datasets by leveraging multi-core processors.
+   * - Reduction in memory usage and improvement in processing time by limiting the
+   *   number of returned records.
+   * - Scalability and easy integration with existing systems.
+   *
+   * @param diskUsageList the list of DiskUsage objects to be sorted.
+   * @param limit the maximum number of DiskUsage objects to return.
+   * @return a list of the top N DiskUsage objects sorted in descending order by size,
+   *  where N is the specified limit.
+   */
+  public static List<DUResponse.DiskUsage> sortDiskUsageDescendingWithLimit(
+      List<DUResponse.DiskUsage> diskUsageList, int limit) {
+    return diskUsageList.parallelStream()
+        .sorted((du1, du2) -> Long.compare(du2.getSize(), du1.getSize()))
+        .limit(limit)
+        .collect(Collectors.toList());
+  }
+
   public static long getFileSizeUpperBound(long fileSize) {
     if (fileSize >= ReconConstants.MAX_FILE_SIZE_UPPER_BOUND) {
       return Long.MAX_VALUE;

hadoop-ozone/recon/src/main/java/org/apache/hadoop/ozone/recon/api/NSSummaryEndpoint.java

@@ -101,17 +101,18 @@ public Response getBasicInfo(
    * @param path request path
    * @param listFile show subpath/disk usage for each key
    * @param withReplica count actual DU with replication
+   * @param sortSubpaths determines whether to sort the subpaths by their sizes in descending order
+   * and returns the N largest subpaths based on the configuration value DISK_USAGE_TOP_RECORDS_LIMIT.
    * @return DU response
    * @throws IOException
    */
   @GET
   @Path("/du")
   @SuppressWarnings("methodlength")
   public Response getDiskUsage(@QueryParam("path") String path,
-                               @DefaultValue("false")
-                               @QueryParam("files") boolean listFile,
-                               @DefaultValue("false")
-                               @QueryParam("replica") boolean withReplica)
+                               @DefaultValue("false") @QueryParam("files") boolean listFile,
+                               @DefaultValue("false") @QueryParam("replica") boolean withReplica,
+                               @DefaultValue("true") @QueryParam("sortSubPaths") boolean sortSubpaths)
       throws IOException {
     if (path == null || path.length() == 0) {
       return Response.status(Response.Status.BAD_REQUEST).build();
@@ -127,8 +128,7 @@ public Response getDiskUsage(@QueryParam("path") String path,
             reconNamespaceSummaryManager,
             omMetadataManager, reconSCM, path);
 
-    duResponse = handler.getDuResponse(
-            listFile, withReplica);
+    duResponse = handler.getDuResponse(listFile, withReplica, sortSubpaths);
 
     return Response.ok(duResponse).build();
   }

hadoop-ozone/recon/src/main/java/org/apache/hadoop/ozone/recon/api/handlers/BucketEntityHandler.java

@@ -36,6 +36,9 @@
 import java.util.List;
 import java.util.Set;
 
+import static org.apache.hadoop.ozone.recon.ReconConstants.DISK_USAGE_TOP_RECORDS_LIMIT;
+import static org.apache.hadoop.ozone.recon.ReconUtils.sortDiskUsageDescendingWithLimit;
+
 /**
  * Class for handling bucket entity type.
  */
@@ -87,7 +90,7 @@ private BucketObjectDBInfo getBucketObjDbInfo(String[] names)
 
   @Override
   public DUResponse getDuResponse(
-          boolean listFile, boolean withReplica)
+      boolean listFile, boolean withReplica, boolean sortSubpaths)
           throws IOException {
     DUResponse duResponse = new DUResponse();
     duResponse.setPath(getNormalizedPath());
@@ -142,7 +145,15 @@ public DUResponse getDuResponse(
     }
     duResponse.setCount(dirDUData.size());
     duResponse.setSize(bucketDataSize);
+
+    if (sortSubpaths) {
+      // Parallel sort directory/files DU data in descending order of size and returns the top N elements.
+      dirDUData = sortDiskUsageDescendingWithLimit(dirDUData,
+          DISK_USAGE_TOP_RECORDS_LIMIT);
+    }
+
     duResponse.setDuData(dirDUData);
+
     return duResponse;
   }
 

hadoop-ozone/recon/src/main/java/org/apache/hadoop/ozone/recon/api/handlers/DirectoryEntityHandler.java

@@ -39,6 +39,9 @@
 import java.util.List;
 import java.util.Set;
 
+import static org.apache.hadoop.ozone.recon.ReconConstants.DISK_USAGE_TOP_RECORDS_LIMIT;
+import static org.apache.hadoop.ozone.recon.ReconUtils.sortDiskUsageDescendingWithLimit;
+
 /**
  * Class for handling directory entity type.
  */
@@ -80,7 +83,7 @@ private ObjectDBInfo getDirectoryObjDbInfo(String[] names)
 
   @Override
   public DUResponse getDuResponse(
-          boolean listFile, boolean withReplica)
+      boolean listFile, boolean withReplica, boolean sortSubPaths)
           throws IOException {
     DUResponse duResponse = new DUResponse();
     duResponse.setPath(getNormalizedPath());
@@ -154,6 +157,13 @@ public DUResponse getDuResponse(
     }
     duResponse.setCount(subdirDUData.size());
     duResponse.setSize(dirDataSize);
+
+    if (sortSubPaths) {
+      // Parallel sort subdirDUData in descending order of size and returns the top N elements.
+      subdirDUData = sortDiskUsageDescendingWithLimit(subdirDUData,
+          DISK_USAGE_TOP_RECORDS_LIMIT);
+    }
+
     duResponse.setDuData(subdirDUData);
 
     return duResponse;

hadoop-ozone/recon/src/main/java/org/apache/hadoop/ozone/recon/api/handlers/EntityHandler.java

@@ -79,7 +79,7 @@ public abstract NamespaceSummaryResponse getSummaryResponse()
           throws IOException;
 
   public abstract DUResponse getDuResponse(
-          boolean listFile, boolean withReplica)
+      boolean listFile, boolean withReplica, boolean sort)
           throws IOException;
 
   public abstract QuotaUsageResponse getQuotaResponse()

hadoop-ozone/recon/src/main/java/org/apache/hadoop/ozone/recon/api/handlers/KeyEntityHandler.java

@@ -71,7 +71,7 @@ private ObjectDBInfo getKeyDbObjectInfo(String[] names)
 
   @Override
   public DUResponse getDuResponse(
-          boolean listFile, boolean withReplica)
+      boolean listFile, boolean withReplica, boolean sort)
           throws IOException {
     DUResponse duResponse = new DUResponse();
     duResponse.setPath(getNormalizedPath());

hadoop-ozone/recon/src/main/java/org/apache/hadoop/ozone/recon/api/handlers/RootEntityHandler.java

@@ -39,6 +39,9 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import static org.apache.hadoop.ozone.recon.ReconConstants.DISK_USAGE_TOP_RECORDS_LIMIT;
+import static org.apache.hadoop.ozone.recon.ReconUtils.sortDiskUsageDescendingWithLimit;
+
 /**
  * Class for handling root entity type.
  */
@@ -88,7 +91,7 @@ private ObjectDBInfo getPrefixObjDbInfo()
 
   @Override
   public DUResponse getDuResponse(
-          boolean listFile, boolean withReplica)
+      boolean listFile, boolean withReplica, boolean sortSubPaths)
           throws IOException {
     DUResponse duResponse = new DUResponse();
     duResponse.setPath(getNormalizedPath());
@@ -137,6 +140,13 @@ public DUResponse getDuResponse(
       duResponse.setSizeWithReplica(totalDataSizeWithReplica);
     }
     duResponse.setSize(totalDataSize);
+
+    if (sortSubPaths) {
+      // Parallel sort volumeDuData in descending order of size and returns the top N elements.
+      volumeDuData = sortDiskUsageDescendingWithLimit(volumeDuData,
+          DISK_USAGE_TOP_RECORDS_LIMIT);
+    }
+
     duResponse.setDuData(volumeDuData);
 
     return duResponse;
@@ -148,7 +158,8 @@ public QuotaUsageResponse getQuotaResponse()
     QuotaUsageResponse quotaUsageResponse = new QuotaUsageResponse();
     SCMNodeStat stats = getReconSCM().getScmNodeManager().getStats();
     long quotaInBytes = stats.getCapacity().get();
-    long quotaUsedInBytes = getDuResponse(true, true).getSizeWithReplica();
+    long quotaUsedInBytes =
+        getDuResponse(true, true, false).getSizeWithReplica();
     quotaUsageResponse.setQuota(quotaInBytes);
     quotaUsageResponse.setQuotaUsed(quotaUsedInBytes);
     return quotaUsageResponse;

hadoop-ozone/recon/src/main/java/org/apache/hadoop/ozone/recon/api/handlers/UnknownEntityHandler.java

@@ -51,7 +51,7 @@ public NamespaceSummaryResponse getSummaryResponse()
 
   @Override
   public DUResponse getDuResponse(
-          boolean listFile, boolean withReplica)
+      boolean listFile, boolean withReplica, boolean sort)
           throws IOException {
     DUResponse duResponse = new DUResponse();
     duResponse.setStatus(ResponseStatus.PATH_NOT_FOUND);

hadoop-ozone/recon/src/main/java/org/apache/hadoop/ozone/recon/api/handlers/VolumeEntityHandler.java

@@ -36,6 +36,10 @@
 import java.util.ArrayList;
 import java.util.List;
 
+
+import static org.apache.hadoop.ozone.recon.ReconConstants.DISK_USAGE_TOP_RECORDS_LIMIT;
+import static org.apache.hadoop.ozone.recon.ReconUtils.sortDiskUsageDescendingWithLimit;
+
 /**
  * Class for handling volume entity type.
  */
@@ -92,7 +96,7 @@ private VolumeObjectDBInfo getVolumeObjDbInfo(String[] names)
 
   @Override
   public DUResponse getDuResponse(
-          boolean listFile, boolean withReplica)
+      boolean listFile, boolean withReplica, boolean sortSubPaths)
           throws IOException {
     DUResponse duResponse = new DUResponse();
     duResponse.setPath(getNormalizedPath());
@@ -131,6 +135,13 @@ public DUResponse getDuResponse(
       duResponse.setSizeWithReplica(volDataSizeWithReplica);
     }
     duResponse.setSize(volDataSize);
+
+    if (sortSubPaths) {
+      // Parallel sort bucketDuData in descending order of size and returns the top N elements.
+      bucketDuData = sortDiskUsageDescendingWithLimit(bucketDuData,
+          DISK_USAGE_TOP_RECORDS_LIMIT);
+    }
+
     duResponse.setDuData(bucketDuData);
     return duResponse;
   }

hadoop-ozone/recon/src/main/java/org/apache/hadoop/ozone/recon/heatmap/HeatMapUtil.java

@@ -71,7 +71,7 @@ private long getEntitySize(String path) throws IOException {
         EntityHandler.getEntityHandler(reconNamespaceSummaryManager,
             omMetadataManager, reconSCM, path);
     if (null != entityHandler) {
-      DUResponse duResponse = entityHandler.getDuResponse(false, false);
+      DUResponse duResponse = entityHandler.getDuResponse(false, false, false);
       if (null != duResponse && duResponse.getStatus() == ResponseStatus.OK) {
         return duResponse.getSize();
       }