MAPREDUCE-7241. FileInputFormat listStatus with less memory footprint. Contributed by Zhihua Deng

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/FileInputFormat.java

@@ -193,7 +193,8 @@ protected void addInputPathRecursively(List<FileStatus> result,
         if (stat.isDirectory()) {
           addInputPathRecursively(result, fs, stat.getPath(), inputFilter);
         } else {
-          result.add(stat);
+          result.add(org.apache.hadoop.mapreduce.lib.input.
+              FileInputFormat.shrinkStatus(stat));
         }
       }
     }
@@ -290,7 +291,8 @@ private List<FileStatus> singleThreadedListStatus(JobConf job, Path[] dirs,
                   addInputPathRecursively(result, fs, stat.getPath(),
                       inputFilter);
                 } else {
-                  result.add(stat);
+                  result.add(org.apache.hadoop.mapreduce.lib.input.
+                      FileInputFormat.shrinkStatus(stat));
                 }
               }
             }

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/LocatedFileStatusFetcher.java

@@ -259,7 +259,8 @@ public Result call() throws Exception {
             if (recursive && stat.isDirectory()) {
               result.dirsNeedingRecursiveCalls.add(stat);
             } else {
-              result.locatedFileStatuses.add(stat);
+              result.locatedFileStatuses.add(org.apache.hadoop.mapreduce.lib.
+                  input.FileInputFormat.shrinkStatus(stat));
             }
           }
         }

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/lib/input/FileInputFormat.java

@@ -325,7 +325,7 @@ private List<FileStatus> singleThreadedListStatus(JobContext job, Path[] dirs,
                   addInputPathRecursively(result, fs, stat.getPath(),
                       inputFilter);
                 } else {
-                  result.add(stat);
+                  result.add(shrinkStatus(stat));
                 }
               }
             }
@@ -364,13 +364,42 @@ protected void addInputPathRecursively(List<FileStatus> result,
         if (stat.isDirectory()) {
           addInputPathRecursively(result, fs, stat.getPath(), inputFilter);
         } else {
-          result.add(stat);
+          result.add(shrinkStatus(stat));
         }
       }
     }
   }
-  
+
-  
+  /**
+   * The HdfsBlockLocation includes a LocatedBlock which contains messages
+   * for issuing more detailed queries to datanodes about a block, but these
+   * messages are useless during job submission currently. This method tries
+   * to exclude the LocatedBlock from HdfsBlockLocation by creating a new
+   * BlockLocation from original, reshaping the LocatedFileStatus,
+   * allowing {@link #listStatus(JobContext)} to scan more files with less
+   * memory footprint.
+   * @see BlockLocation
+   * @see org.apache.hadoop.fs.HdfsBlockLocation
+   * @param origStat The fat FileStatus.
+   * @return The FileStatus that has been shrunk.
+   */
+  public static FileStatus shrinkStatus(FileStatus origStat) {
+    if (origStat.isDirectory() || origStat.getLen() == 0 ||
+        !(origStat instanceof LocatedFileStatus)) {
+      return origStat;
+    } else {
+      BlockLocation[] blockLocations =
+          ((LocatedFileStatus)origStat).getBlockLocations();
+      BlockLocation[] locs = new BlockLocation[blockLocations.length];
+      int i = 0;
+      for (BlockLocation location : blockLocations) {
+        locs[i++] = new BlockLocation(location);
+      }
+      LocatedFileStatus newStat = new LocatedFileStatus(origStat, locs);
+      return newStat;
+    }
+  }
+
   /**
    * A factory that makes the split for this class. It can be overridden
    * by sub-classes to make sub-types

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/test/java/org/apache/hadoop/mapreduce/lib/input/TestFileInputFormat.java

@@ -32,11 +32,17 @@
 import org.apache.hadoop.fs.BlockLocation;
 import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.HdfsBlockLocation;
 import org.apache.hadoop.fs.LocatedFileStatus;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.PathFilter;
 import org.apache.hadoop.fs.RawLocalFileSystem;
 import org.apache.hadoop.fs.RemoteIterator;
+import org.apache.hadoop.hdfs.protocol.DatanodeID;
+import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
+import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
+import org.apache.hadoop.hdfs.protocol.LocatedBlock;
+import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor;
 import org.apache.hadoop.mapred.SplitLocationInfo;
 import org.apache.hadoop.mapreduce.InputSplit;
 import org.apache.hadoop.mapreduce.Job;
@@ -238,6 +244,50 @@ public void testListStatusErrorOnNonExistantDir() throws IOException {
     }
   }
 
+  @Test
+  public void testShrinkStatus() throws IOException {
+    Configuration conf = getConfiguration();
+    MockFileSystem mockFs =
+            (MockFileSystem) new Path("test:///").getFileSystem(conf);
+    Path dir1  = new Path("test:/a1");
+    RemoteIterator<LocatedFileStatus> statuses = mockFs.listLocatedStatus(dir1);
+    boolean verified = false;
+    while (statuses.hasNext()) {
+      LocatedFileStatus orig = statuses.next();
+      LocatedFileStatus shrink =
+          (LocatedFileStatus)FileInputFormat.shrinkStatus(orig);
+      Assert.assertTrue(orig.equals(shrink));
+      if (shrink.getBlockLocations() != null) {
+        Assert.assertEquals(orig.getBlockLocations().length,
+            shrink.getBlockLocations().length);
+        for (int i = 0; i < shrink.getBlockLocations().length; i++) {
+          verified = true;
+          BlockLocation location = shrink.getBlockLocations()[i];
+          BlockLocation actual = orig.getBlockLocations()[i];
+          Assert.assertNotNull(((HdfsBlockLocation)actual).getLocatedBlock());
+          Assert.assertEquals(BlockLocation.class.getName(),
+              location.getClass().getName());
+          Assert.assertArrayEquals(actual.getHosts(), location.getHosts());
+          Assert.assertArrayEquals(actual.getCachedHosts(),
+              location.getCachedHosts());
+          Assert.assertArrayEquals(actual.getStorageIds(),
+              location.getStorageIds());
+          Assert.assertArrayEquals(actual.getStorageTypes(),
+              location.getStorageTypes());
+          Assert.assertArrayEquals(actual.getTopologyPaths(),
+              location.getTopologyPaths());
+          Assert.assertArrayEquals(actual.getNames(), location.getNames());
+          Assert.assertEquals(actual.getLength(), location.getLength());
+          Assert.assertEquals(actual.getOffset(), location.getOffset());
+          Assert.assertEquals(actual.isCorrupt(), location.isCorrupt());
+        }
+      } else {
+        Assert.assertTrue(orig.getBlockLocations() == null);
+      }
+    }
+    Assert.assertTrue(verified);
+  }
+
   public static List<Path> configureTestSimple(Configuration conf, FileSystem localFs)
       throws IOException {
     Path base1 = new Path(TEST_ROOT_DIR, "input1");
@@ -437,10 +487,31 @@ public FileStatus[] listStatus(Path f, PathFilter filter)
     @Override
     public BlockLocation[] getFileBlockLocations(FileStatus file, long start, long len)
         throws IOException {
-      return new BlockLocation[] {
+      DatanodeInfo[] ds = new DatanodeInfo[2];
-          new BlockLocation(new String[] { "localhost:9866", "otherhost:9866" },
+      ds[0] = new DatanodeDescriptor(
-              new String[] { "localhost", "otherhost" }, new String[] { "localhost" },
+          new DatanodeID("127.0.0.1", "localhost", "abcd",
-              new String[0], 0, len, false) };    }
+              9866, 9867, 9868, 9869));
+      ds[1] = new DatanodeDescriptor(
+          new DatanodeID("1.0.0.1", "otherhost", "efgh",
+              9866, 9867, 9868, 9869));
+      long blockLen = len / 3;
+      ExtendedBlock b1 = new ExtendedBlock("bpid", 0, blockLen, 0);
+      ExtendedBlock b2 = new ExtendedBlock("bpid", 1, blockLen, 1);
+      ExtendedBlock b3 = new ExtendedBlock("bpid", 2, len - 2 * blockLen, 2);
+      String[] names = new String[]{ "localhost:9866", "otherhost:9866" };
+      String[] hosts = new String[]{ "localhost", "otherhost" };
+      String[] cachedHosts = {"localhost"};
+      BlockLocation loc1 = new BlockLocation(names, hosts, cachedHosts,
+          new String[0], 0, blockLen, false);
+      BlockLocation loc2 = new BlockLocation(names, hosts, cachedHosts,
+          new String[0], blockLen, blockLen, false);
+      BlockLocation loc3 = new BlockLocation(names, hosts, cachedHosts,
+          new String[0], 2 * blockLen, len - 2 * blockLen, false);
+      return new BlockLocation[]{
+          new HdfsBlockLocation(loc1, new LocatedBlock(b1, ds)),
+          new HdfsBlockLocation(loc2, new LocatedBlock(b2, ds)),
+          new HdfsBlockLocation(loc3, new LocatedBlock(b3, ds)) };
+    }
 
     @Override
     protected RemoteIterator<LocatedFileStatus> listLocatedStatus(Path f,