HDFS-2943. Expose last checkpoint time and transaction stats as JMX metrics. Contributed by Aaron T. Myers.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1243823 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -11,6 +11,9 @@ Release 0.23.2 - UNRELEASED
 
   NEW FEATURES
 
+    HDFS-2943. Expose last checkpoint time and transaction stats as JMX
+    metrics. (atm)
+
   IMPROVEMENTS
 
     HDFS-2931. Switch DataNode's BlockVolumeChoosingPolicy to private-audience.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImage.java

@@ -724,7 +724,7 @@ public class FSImage implements Closeable {
     long txId = loader.getLoadedImageTxId();
     LOG.info("Loaded image for txid " + txId + " from " + curFile);
     lastAppliedTxId = txId;
-    storage.setMostRecentCheckpointTxId(txId);
+    storage.setMostRecentCheckpointInfo(txId, curFile.lastModified());
   }
 
   /**
@@ -739,7 +739,7 @@ public class FSImage implements Closeable {
     saver.save(newFile, txid, getFSNamesystem(), compression);
     
     MD5FileUtils.saveMD5File(dstFile, saver.getSavedDigest());
-    storage.setMostRecentCheckpointTxId(txid);
+    storage.setMostRecentCheckpointInfo(txid, Util.now());
   }
 
   /**
@@ -997,7 +997,7 @@ public class FSImage implements Closeable {
     // advertise it as such to other checkpointers
     // from now on
     if (txid > storage.getMostRecentCheckpointTxId()) {
-      storage.setMostRecentCheckpointTxId(txid);
+      storage.setMostRecentCheckpointInfo(txid, Util.now());
     }
   }
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java

@@ -2626,6 +2626,31 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     return datanodeStatistics.getExpiredHeartbeats();
   }
   
+  @Metric({"TransactionsSinceLastCheckpoint",
+      "Number of transactions since last checkpoint"})
+  public long getTransactionsSinceLastCheckpoint() {
+    return getEditLog().getLastWrittenTxId() -
+        getFSImage().getStorage().getMostRecentCheckpointTxId();
+  }
+  
+  @Metric({"TransactionsSinceLastLogRoll",
+      "Number of transactions since last edit log roll"})
+  public long getTransactionsSinceLastLogRoll() {
+    return (getEditLog().getLastWrittenTxId() -
+        getEditLog().getCurSegmentTxId()) + 1;
+  }
+  
+  @Metric({"LastWrittenTransactionId", "Transaction ID written to the edit log"})
+  public long getLastWrittenTransactionId() {
+    return getEditLog().getLastWrittenTxId();
+  }
+  
+  @Metric({"LastCheckpointTime",
+      "Time in milliseconds since the epoch of the last checkpoint"})
+  public long getLastCheckpointTime() {
+    return getFSImage().getStorage().getMostRecentCheckpointTime();
+  }
+
   /** @see ClientProtocol#getStats() */
   long[] getStats() {
     final long[] stats = datanodeStatistics.getStats();

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NNStorage.java

@@ -126,6 +126,11 @@ public class NNStorage extends Storage implements Closeable {
    */
   protected long mostRecentCheckpointTxId = HdfsConstants.INVALID_TXID;
   
+  /**
+   * Time of the last checkpoint, in milliseconds since the epoch.
+   */
+  private long mostRecentCheckpointTime = 0;
+
   /**
    * list of failed (and thus removed) storages
    */
@@ -417,19 +422,30 @@ public class NNStorage extends Storage implements Closeable {
   }
 
   /**
-   * Set the transaction ID of the last checkpoint
+   * Set the transaction ID and time of the last checkpoint
+   * 
+   * @param txid transaction id of the last checkpoint
+   * @param time time of the last checkpoint, in millis since the epoch
    */
-  void setMostRecentCheckpointTxId(long txid) {
+  void setMostRecentCheckpointInfo(long txid, long time) {
     this.mostRecentCheckpointTxId = txid;
+    this.mostRecentCheckpointTime = time;
   }
 
   /**
-   * Return the transaction ID of the last checkpoint.
+   * @return the transaction ID of the last checkpoint.
    */
   long getMostRecentCheckpointTxId() {
     return mostRecentCheckpointTxId;
   }
   
+  /**
+   * @return the time of the most recent checkpoint in millis since the epoch.
+   */
+  long getMostRecentCheckpointTime() {
+    return mostRecentCheckpointTime;
+  }
+
   /**
    * Write a small file in all available storage directories that
    * indicates that the namespace has reached some given transaction ID.

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/metrics/TestNameNodeMetrics.java

@@ -20,13 +20,12 @@ package org.apache.hadoop.hdfs.server.namenode.metrics;
 import static org.apache.hadoop.test.MetricsAsserts.assertCounter;
 import static org.apache.hadoop.test.MetricsAsserts.assertGauge;
 import static org.apache.hadoop.test.MetricsAsserts.getMetrics;
+import static org.junit.Assert.*;
 
 import java.io.DataInputStream;
 import java.io.IOException;
 import java.util.Random;
 
-import junit.framework.TestCase;
-
 import org.apache.commons.logging.LogFactory;
 import org.apache.commons.logging.impl.Log4JLogger;
 import org.apache.hadoop.conf.Configuration;
@@ -39,17 +38,21 @@ import org.apache.hadoop.hdfs.DistributedFileSystem;
 import org.apache.hadoop.hdfs.HdfsConfiguration;
 import org.apache.hadoop.hdfs.MiniDFSCluster;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction;
 import org.apache.hadoop.hdfs.server.blockmanagement.BlockManager;
 import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
 import org.apache.hadoop.hdfs.server.namenode.NameNodeAdapter;
 import org.apache.hadoop.metrics2.MetricsRecordBuilder;
 import org.apache.hadoop.test.MetricsAsserts;
 import org.apache.log4j.Level;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
 
 /**
  * Test for metrics published by the Namenode
  */
-public class TestNameNodeMetrics extends TestCase {
+public class TestNameNodeMetrics {
   private static final Configuration CONF = new HdfsConfiguration();
   private static final int DFS_REPLICATION_INTERVAL = 1;
   private static final Path TEST_ROOT_DIR_PATH = 
@@ -81,8 +84,8 @@ public class TestNameNodeMetrics extends TestCase {
     return new Path(TEST_ROOT_DIR_PATH, fileName);
   }
   
-  @Override
+  @Before
-  protected void setUp() throws Exception {
+  public void setUp() throws Exception {
     cluster = new MiniDFSCluster.Builder(CONF).numDataNodes(DATANODE_COUNT).build();
     cluster.waitActive();
     namesystem = cluster.getNamesystem();
@@ -90,8 +93,8 @@ public class TestNameNodeMetrics extends TestCase {
     fs = (DistributedFileSystem) cluster.getFileSystem();
   }
   
-  @Override
+  @After
-  protected void tearDown() throws Exception {
+  public void tearDown() throws Exception {
     cluster.shutdown();
   }
   
@@ -115,6 +118,7 @@ public class TestNameNodeMetrics extends TestCase {
   }
   
   /** Test metrics associated with addition of a file */
+  @Test
   public void testFileAdd() throws Exception {
     // Add files with 100 blocks
     final Path file = getTestPath("testFileAdd");
@@ -161,6 +165,7 @@ public class TestNameNodeMetrics extends TestCase {
   }
   
   /** Corrupt a block and ensure metrics reflects it */
+  @Test
   public void testCorruptBlock() throws Exception {
     // Create a file with single block with two replicas
     final Path file = getTestPath("testCorruptBlock");
@@ -186,6 +191,7 @@ public class TestNameNodeMetrics extends TestCase {
   /** Create excess blocks by reducing the replication factor for
    * for a file and ensure metrics reflects it
    */
+  @Test
   public void testExcessBlocks() throws Exception {
     Path file = getTestPath("testExcessBlocks");
     createFile(file, 100, (short)2);
@@ -198,6 +204,7 @@ public class TestNameNodeMetrics extends TestCase {
   }
   
   /** Test to ensure metrics reflects missing blocks */
+  @Test
   public void testMissingBlock() throws Exception {
     // Create a file with single block with two replicas
     Path file = getTestPath("testMissingBlocks");
@@ -216,6 +223,7 @@ public class TestNameNodeMetrics extends TestCase {
     assertGauge("UnderReplicatedBlocks", 0L, getMetrics(NS_METRICS));
   }
   
+  @Test
   public void testRenameMetrics() throws Exception {
     Path src = getTestPath("src");
     createFile(src, 100, (short)1);
@@ -240,6 +248,7 @@ public class TestNameNodeMetrics extends TestCase {
    *    
    * @throws IOException in case of an error
    */
+  @Test
   public void testGetBlockLocationMetric() throws Exception {
     Path file1_Path = new Path(TEST_ROOT_DIR_PATH, "file1.dat");
 
@@ -268,4 +277,46 @@ public class TestNameNodeMetrics extends TestCase {
     updateMetrics();
     assertCounter("GetBlockLocations", 3L, getMetrics(NN_METRICS));
   }
+  
+  /**
+   * Test NN checkpoint and transaction-related metrics.
+   */
+  @Test
+  public void testTransactionAndCheckpointMetrics() throws Exception {
+    long lastCkptTime = MetricsAsserts.getLongGauge("LastCheckpointTime",
+        getMetrics(NS_METRICS));
+    
+    assertGauge("LastCheckpointTime", lastCkptTime, getMetrics(NS_METRICS));
+    assertGauge("LastWrittenTransactionId", 1L, getMetrics(NS_METRICS));
+    assertGauge("TransactionsSinceLastCheckpoint", 1L, getMetrics(NS_METRICS));
+    assertGauge("TransactionsSinceLastLogRoll", 1L, getMetrics(NS_METRICS));
+    
+    fs.mkdirs(new Path(TEST_ROOT_DIR_PATH, "/tmp"));
+    updateMetrics();
+    
+    assertGauge("LastCheckpointTime", lastCkptTime, getMetrics(NS_METRICS));
+    assertGauge("LastWrittenTransactionId", 2L, getMetrics(NS_METRICS));
+    assertGauge("TransactionsSinceLastCheckpoint", 2L, getMetrics(NS_METRICS));
+    assertGauge("TransactionsSinceLastLogRoll", 2L, getMetrics(NS_METRICS));
+    
+    cluster.getNameNodeRpc().rollEditLog();
+    updateMetrics();
+    
+    assertGauge("LastCheckpointTime", lastCkptTime, getMetrics(NS_METRICS));
+    assertGauge("LastWrittenTransactionId", 4L, getMetrics(NS_METRICS));
+    assertGauge("TransactionsSinceLastCheckpoint", 4L, getMetrics(NS_METRICS));
+    assertGauge("TransactionsSinceLastLogRoll", 1L, getMetrics(NS_METRICS));
+    
+    cluster.getNameNodeRpc().setSafeMode(SafeModeAction.SAFEMODE_ENTER);
+    cluster.getNameNodeRpc().saveNamespace();
+    cluster.getNameNodeRpc().setSafeMode(SafeModeAction.SAFEMODE_LEAVE);
+    updateMetrics();
+    
+    long newLastCkptTime = MetricsAsserts.getLongGauge("LastCheckpointTime",
+        getMetrics(NS_METRICS));
+    assertTrue(lastCkptTime < newLastCkptTime);
+    assertGauge("LastWrittenTransactionId", 6L, getMetrics(NS_METRICS));
+    assertGauge("TransactionsSinceLastCheckpoint", 1L, getMetrics(NS_METRICS));
+    assertGauge("TransactionsSinceLastLogRoll", 1L, getMetrics(NS_METRICS));
+  }
 }