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From hair...@apache.org
Subject svn commit: r1038859 - in /hadoop/hdfs/trunk: CHANGES.txt src/java/org/apache/hadoop/hdfs/server/namenode/SecondaryNameNode.java src/test/hdfs/org/apache/hadoop/hdfs/server/namenode/TestCheckpoint.java
Date Wed, 24 Nov 2010 22:57:12 GMT
Author: hairong
Date: Wed Nov 24 22:57:11 2010
New Revision: 1038859

URL: http://svn.apache.org/viewvc?rev=1038859&view=rev
Log:
HDFS-1458. Improve checkpoint performance by avoiding unnecessary image downloads and loading.
Contributed by Hairong Kuang.

Modified:
    hadoop/hdfs/trunk/CHANGES.txt
    hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/SecondaryNameNode.java
    hadoop/hdfs/trunk/src/test/hdfs/org/apache/hadoop/hdfs/server/namenode/TestCheckpoint.java

Modified: hadoop/hdfs/trunk/CHANGES.txt
URL: http://svn.apache.org/viewvc/hadoop/hdfs/trunk/CHANGES.txt?rev=1038859&r1=1038858&r2=1038859&view=diff
==============================================================================
--- hadoop/hdfs/trunk/CHANGES.txt (original)
+++ hadoop/hdfs/trunk/CHANGES.txt Wed Nov 24 22:57:11 2010
@@ -17,6 +17,9 @@ Trunk (unreleased changes)
 
   OPTIMIZATIONS
 
+    HDFS-1458. Improve checkpoint performance by avoiding unnecessary image
+    downloads and loading. (hairong)
+
   BUG FIXES
 
     HDFS-1516. mvn-install is broken after 0.22 branch creation. (cos)

Modified: hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/SecondaryNameNode.java
URL: http://svn.apache.org/viewvc/hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/SecondaryNameNode.java?rev=1038859&r1=1038858&r2=1038859&view=diff
==============================================================================
--- hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/SecondaryNameNode.java
(original)
+++ hadoop/hdfs/trunk/src/java/org/apache/hadoop/hdfs/server/namenode/SecondaryNameNode.java
Wed Nov 24 22:57:11 2010
@@ -312,6 +312,7 @@ public class SecondaryNameNode implement
         LOG.error("Exception in doCheckpoint: ");
         LOG.error(StringUtils.stringifyException(e));
         e.printStackTrace();
+        checkpointImage.imageDigest = null;
       } catch (Throwable e) {
         LOG.error("Throwable Exception in doCheckpoint: ");
         LOG.error(StringUtils.stringifyException(e));
@@ -324,28 +325,39 @@ public class SecondaryNameNode implement
   /**
    * Download <code>fsimage</code> and <code>edits</code>
    * files from the name-node.
+   * @return true if a new image has been downloaded and needs to be loaded
    * @throws IOException
    */
-  private void downloadCheckpointFiles(final CheckpointSignature sig
+  private boolean downloadCheckpointFiles(final CheckpointSignature sig
                                       ) throws IOException {
     try {
-        UserGroupInformation.getCurrentUser().doAs(new PrivilegedExceptionAction<Void>()
{
+        Boolean b = UserGroupInformation.getCurrentUser().doAs(
+            new PrivilegedExceptionAction<Boolean>() {
   
           @Override
-          public Void run() throws Exception {
+          public Boolean run() throws Exception {
             checkpointImage.cTime = sig.cTime;
             checkpointImage.checkpointTime = sig.checkpointTime;
-            checkpointImage.imageDigest = sig.imageDigest;
-        
+                    
             // get fsimage
-            String fileid = "getimage=1";
-            Collection<File> list = checkpointImage.getFiles(NameNodeFile.IMAGE,
-                NameNodeDirType.IMAGE);
-            File[] srcNames = list.toArray(new File[list.size()]);
-            assert srcNames.length > 0 : "No checkpoint targets.";
-            TransferFsImage.getFileClient(fsName, fileid, srcNames, false);
-            LOG.info("Downloaded file " + srcNames[0].getName() + " size " +
-                     srcNames[0].length() + " bytes.");
+            String fileid;
+            Collection<File> list;
+            File[] srcNames;
+            boolean downloadImage = true;
+            if (sig.imageDigest.equals(checkpointImage.imageDigest)) {
+              downloadImage = false;
+              LOG.info("Image has not changed. Will not download image.");
+            } else {
+              fileid = "getimage=1";
+              list = checkpointImage.getFiles(NameNodeFile.IMAGE,
+                  NameNodeDirType.IMAGE);
+              srcNames = list.toArray(new File[list.size()]);
+              assert srcNames.length > 0 : "No checkpoint targets.";
+              TransferFsImage.getFileClient(fsName, fileid, srcNames, false);
+              checkpointImage.imageDigest = sig.imageDigest;
+              LOG.info("Downloaded file " + srcNames[0].getName() + " size " +
+                  srcNames[0].length() + " bytes.");
+            }
         
             // get edits file
             fileid = "getedit=1";
@@ -357,9 +369,10 @@ public class SecondaryNameNode implement
                 srcNames[0].length() + " bytes.");
         
             checkpointImage.checkpointUploadDone();
-            return null;
+            return Boolean.valueOf(downloadImage);
           }
         });
+        return b.booleanValue();
       } catch (InterruptedException e) {
         throw new RuntimeException(e);
       }
@@ -404,8 +417,9 @@ public class SecondaryNameNode implement
 
   /**
    * Create a new checkpoint
+   * @return if the image is fetched from primary or not
    */
-  void doCheckpoint() throws IOException {
+  boolean doCheckpoint() throws IOException {
 
     // Do the required initialization of the merge work area.
     startCheckpoint();
@@ -420,8 +434,8 @@ public class SecondaryNameNode implement
                             "after creating edits.new");
     }
 
-    downloadCheckpointFiles(sig);   // Fetch fsimage and edits
-    doMerge(sig);                   // Do the merge
+    boolean loadImage = downloadCheckpointFiles(sig);   // Fetch fsimage and edits
+    doMerge(sig, loadImage);                   // Do the merge
   
     //
     // Upload the new image into the NameNode. Then tell the Namenode
@@ -440,6 +454,8 @@ public class SecondaryNameNode implement
 
     LOG.warn("Checkpoint done. New Image Size: " 
               + checkpointImage.getFsImageName().length());
+    
+    return loadImage;
   }
 
   private void startCheckpoint() throws IOException {
@@ -453,11 +469,12 @@ public class SecondaryNameNode implement
    * Merge downloaded image and edits and write the new image into
    * current storage directory.
    */
-  private void doMerge(CheckpointSignature sig) throws IOException {
+  private void doMerge(CheckpointSignature sig, boolean loadImage)
+  throws IOException {
     FSNamesystem namesystem = 
             new FSNamesystem(checkpointImage, conf);
     assert namesystem.dir.fsImage == checkpointImage;
-    checkpointImage.doMerge(sig);
+    checkpointImage.doMerge(sig, loadImage);
   }
 
   /**
@@ -661,21 +678,29 @@ public class SecondaryNameNode implement
     /**
      * Merge image and edits, and verify consistency with the signature.
      */
-    private void doMerge(CheckpointSignature sig) throws IOException {
+    private void doMerge(CheckpointSignature sig, boolean loadImage)
+    throws IOException {
       getEditLog().open();
       StorageDirectory sdName = null;
       StorageDirectory sdEdits = null;
       Iterator<StorageDirectory> it = null;
-      it = dirIterator(NameNodeDirType.IMAGE);
-      if (it.hasNext())
-        sdName = it.next();
+      if (loadImage) {
+        it = dirIterator(NameNodeDirType.IMAGE);
+        if (it.hasNext())
+          sdName = it.next();
+        if (sdName == null) {
+          throw new IOException("Could not locate checkpoint fsimage");
+        }
+      }
       it = dirIterator(NameNodeDirType.EDITS);
       if (it.hasNext())
         sdEdits = it.next();
-      if ((sdName == null) || (sdEdits == null))
-        throw new IOException("Could not locate checkpoint directories");
-      this.layoutVersion = -1; // to avoid assert in loadFSImage()
-      loadFSImage(FSImage.getImageFile(sdName, NameNodeFile.IMAGE));
+      if (sdEdits == null)
+        throw new IOException("Could not locate checkpoint edits");
+      if (loadImage) {
+        this.layoutVersion = -1; // to avoid assert in loadFSImage()
+        loadFSImage(FSImage.getImageFile(sdName, NameNodeFile.IMAGE));
+      }
       loadFSEdits(sdEdits);
       sig.validateStorageInfo(this);
       saveNamespace(false);

Modified: hadoop/hdfs/trunk/src/test/hdfs/org/apache/hadoop/hdfs/server/namenode/TestCheckpoint.java
URL: http://svn.apache.org/viewvc/hadoop/hdfs/trunk/src/test/hdfs/org/apache/hadoop/hdfs/server/namenode/TestCheckpoint.java?rev=1038859&r1=1038858&r2=1038859&view=diff
==============================================================================
--- hadoop/hdfs/trunk/src/test/hdfs/org/apache/hadoop/hdfs/server/namenode/TestCheckpoint.java
(original)
+++ hadoop/hdfs/trunk/src/test/hdfs/org/apache/hadoop/hdfs/server/namenode/TestCheckpoint.java
Wed Nov 24 22:57:11 2010
@@ -789,4 +789,56 @@ public class TestCheckpoint extends Test
       if(cluster!= null) cluster.shutdown();
     }
   }
+  
+  /**
+   * Simulate a secondary node failure to transfer image
+   * back to the name-node.
+   * Used to truncate primary fsimage file.
+   */
+  @SuppressWarnings("deprecation")
+  public void testSecondaryImageDownload(Configuration conf)
+    throws IOException {
+    System.out.println("Starting testSecondaryImageDownload");
+    conf.set(DFSConfigKeys.DFS_NAMENODE_SECONDARY_HTTP_ADDRESS_KEY, "0.0.0.0:0");
+    Path dir = new Path("/checkpoint");
+    MiniDFSCluster cluster = new MiniDFSCluster.Builder(conf)
+                                               .numDataNodes(numDatanodes)
+                                               .format(false).build();
+    cluster.waitActive();
+    FileSystem fileSys = cluster.getFileSystem();
+    FSImage image = cluster.getNameNode().getFSImage();
+    try {
+      assertTrue(!fileSys.exists(dir));
+      //
+      // Make the checkpoint
+      //
+      SecondaryNameNode secondary = startSecondaryNameNode(conf);
+      long fsimageLength = FSImage.getImageFile(
+          image.dirIterator(NameNodeDirType.IMAGE).next(),
+          NameNodeFile.IMAGE).length();
+      assertFalse("Image is downloaded", secondary.doCheckpoint());
+
+      // Verify that image file sizes did not change.
+      for (Iterator<StorageDirectory> it = 
+              image.dirIterator(NameNodeDirType.IMAGE); it.hasNext();) {
+        assertTrue("Image size does not change", FSImage.getImageFile(it.next(), 
+                                NameNodeFile.IMAGE).length() == fsimageLength);
+      }
+
+      // change namespace
+      fileSys.mkdirs(dir);
+      assertTrue("Image is not downloaded", secondary.doCheckpoint());
+
+      for (Iterator<StorageDirectory> it = 
+        image.dirIterator(NameNodeDirType.IMAGE); it.hasNext();) {
+        assertTrue("Image size increased", FSImage.getImageFile(it.next(), 
+                          NameNodeFile.IMAGE).length() > fsimageLength);
+     }
+
+      secondary.shutdown();
+    } finally {
+      fileSys.close();
+      cluster.shutdown();
+    }
+  }
 }



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