Examples of org.apache.hadoop.hdfs.server.namenode.AvatarNode

Package org.apache.hadoop.hdfs.server.namenode

Examples of org.apache.hadoop.hdfs.server.namenode.AvatarNode

org.apache.hadoop.hdfs.server.namenode.AvatarNode
This is an implementation of the AvatarNode, a hot standby for the NameNode. This is really cool, believe me! The AvatarNode has two avatars.. the Standby avatar and the Active avatar. In the Standby avatar, the AvatarNode is consuming transaction logs generated by the primary (via a transaction log stored in a shared device). Typically, the primary Namenode is writing transactions to a NFS filesystem and the Standby is reading the log from the same NFS filesystem. The Standby is also making periodic checkpoints to the primary namenode. A manual command can switch the AvatarNode from the Standby avatar to the Active avatar. In the Active avatar, the AvatarNode performs precisely the same functionality as a real usual Namenode. The switching from Standby avatar to the Active avatar is fast and can typically occur within seconds. Typically, an adminstrator will run require two shared mount points for transaction logs. It has to be set in fs.name.dir.shared0 and fs.name.dir.shared1 (similarly for edits). Then the adminstrator starts the AvatarNode on two different machines as follows: bin/hadoop org.apache.hadoop.hdfs.server.namenode.AvatarNode -zero -active bin/hadoop org.apache.hadoop.hdfs.server.namenode.AvatarNode -one -standby The first AvatarNode uses fs.name.dir.shared0 while the second AvatarNode uses fs.name.dir.shared1 to write its transaction logs. Also, at startup, the first instance is the primary Namenode and the second instance is the Standby After a while, the adminstrator decides to change the avatar of the second instance to Active. In this case, he/she has to first ensure that the first instance is really really dead. This code does not handle the split-brain scenario where there are two active namenodes in one cluster.

    LOG.info("TEST Ingest Failure : " + event);
    TestAvatarIngestingHandler h = new TestAvatarIngestingHandler(event);
    InjectionHandler.set(h);
    setUp(3, "testIngestFailure: " + event, false, enableQJM); 
          // simulate interruption, no ckpt failure
    AvatarNode primary = cluster.getPrimaryAvatar(0).avatar;
    AvatarNode standby = cluster.getStandbyAvatar(0).avatar;
    h.setDisabled(false);


    createEdits(20);
    h.setDisabled(true);
    
    if (!enableQJM) {
      standby.quiesceStandby(getCurrentTxId(primary) - 1);
      // SLS + 20 edits
      assertEquals(21, getCurrentTxId(primary));
      assertEquals(getCurrentTxId(primary), getCurrentTxId(standby));
    }
    tearDown();

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    TestAvatarIngestingHandler h = new TestAvatarIngestingHandler(
        InjectionEvent.FSEDIT_LOG_WRITE_END_LOG_SEGMENT);
    InjectionHandler.set(h);
    setUp(3, "testCheckpointWithRestarts", true, false);
    // simulate interruption, no ckpt failure
    AvatarNode primary = cluster.getPrimaryAvatar(0).avatar;
    AvatarNode standby = cluster.getStandbyAvatar(0).avatar;
    createEdits(20);
    h.doCheckpoint();
    // 2 for initial checkpoint + 2 for this checkpoint + SLS + 20 edits
    h.disabled = false;
    assertEquals(25, getCurrentTxId(primary));

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    TestAvatarIngestingHandler h = new TestAvatarIngestingHandler(
        InjectionEvent.STANDBY_RECOVER_STATE);
    InjectionHandler.set(h);
    setUp(3, "testRecoverState", true, false);
    // simulate interruption, no ckpt failure
    AvatarNode primary = cluster.getPrimaryAvatar(0).avatar;
    AvatarNode standby = cluster.getStandbyAvatar(0).avatar;
    h.setDisabled(true);


    createEdits(20);
    h.doCheckpoint();
    // 2 for initial checkpoint + 2 for this checkpoint + SLS + 20 edits
    assertEquals(25, getCurrentTxId(primary));
    createEdits(20);
    h.setDisabled(false);


    // sleep to see if the state recovers correctly
    DFSTestUtil.waitNSecond(5);
    h.doCheckpoint();
    standby.quiesceStandby(getCurrentTxId(primary) - 1);


    assertEquals(47, getCurrentTxId(primary));
    assertEquals(getCurrentTxId(primary), getCurrentTxId(standby));
  }

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  @Test
  public void testWithFailoverTxIdMismatchHard() throws Exception {
    setUp("testWithFailoverTxIdMismatchHard", true);
    // Create edits before failover.
    createEdits(20);
    AvatarNode primary = cluster.getPrimaryAvatar(0).avatar;
    AvatarNode standby = cluster.getStandbyAvatar(0).avatar;


    // SLS + ELS (first checkpoint with no txns) + SLS + 20 edits
    assertEquals(23, getCurrentTxId(primary));


    standby.getFSImage().getEditLog().setLastWrittenTxId(49);
    assertEquals(50, getCurrentTxId(standby));


    // Perform failover and verify it fails.
    try {
      cluster.failOver();

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  @Test
  public void testBasic() throws Exception {
    setUp("testBasic", false);
    createEdits(20);
    AvatarNode primary = cluster.getPrimaryAvatar(0).avatar;
    AvatarNode standby = cluster.getStandbyAvatar(0).avatar;
    standby.quiesceStandby(getCurrentTxId(primary)-1);
    
    // SLS + ELS + SLS + 20 edits
    assertEquals(23, getCurrentTxId(primary));
    assertEquals(getCurrentTxId(primary), getCurrentTxId(standby));
  }

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  protected void doTestWithFailover(boolean enableQJM) throws Exception {
    setUp("testWithFailover", enableQJM);
    // Create edits before failover.
    createEdits(20);
    AvatarNode primary = cluster.getPrimaryAvatar(0).avatar;
    AvatarNode standby = cluster.getStandbyAvatar(0).avatar;
    
    // SLS + ELS (first checkpoint with no txns) + SLS + 20 edits
    assertEquals(23, getCurrentTxId(primary));


    // Perform failover and restart old primary.
    cluster.failOver(); // shutdown adds ELS (24)
    assertEquals(25, getCurrentTxId(cluster.getPrimaryAvatar(0).avatar));
    
    cluster.restartStandby();


    // Get new instances after failover.
    primary = cluster.getPrimaryAvatar(0).avatar;
    standby = cluster.getStandbyAvatar(0).avatar;
    
    // checkpoint by the new standby adds 2 transactions
    // standby opens the log with SLS (25)
    // new standby checkpoints ELS + SLS


    if (!enableQJM) {
      // Create some more edits and verify.
      createEdits(20);
      standby.quiesceStandby(getCurrentTxId(primary)-1);
      
      assertEquals(47, getCurrentTxId(primary));
      assertEquals(getCurrentTxId(primary), getCurrentTxId(standby));
    }
  }

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    // Perform second failover.
    cluster.failOver(); // 49
    cluster.restartStandby(); // 51


    AvatarNode primary = cluster.getPrimaryAvatar(0).avatar;
    AvatarNode standby = cluster.getStandbyAvatar(0).avatar;
    
    if (!enableQJM) {
      createEdits(20);
      standby.quiesceStandby(getCurrentTxId(primary)-1);
      assertEquals(71, getCurrentTxId(primary));
      assertEquals(getCurrentTxId(primary), getCurrentTxId(standby));
    }
  }

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    doTestWithStandbyDead(false);
  }
  
  protected void doTestWithStandbyDead(boolean enableQJM) throws Exception {
    setUp("testWithStandbyDead", enableQJM);
    AvatarNode primary = cluster.getPrimaryAvatar(0).avatar;
    createEdits(20); // 23 (initial checkpoint) + 20 edits
    assertEquals(23, getCurrentTxId(primary));
    
    cluster.killStandby();
    createEdits(20); // 43
    assertEquals(43, getCurrentTxId(primary));
    
    cluster.restartStandby(); // 45 (checkpoint)
    Thread.sleep(1000); // for checkpoint
    assertEquals(45, getCurrentTxId(primary));
    
    createEdits(20); // 67


    AvatarNode standby = cluster.getStandbyAvatar(0).avatar;
    
  if (!enableQJM) {
      standby.quiesceStandby(getCurrentTxId(primary)-1);
      assertEquals(65, getCurrentTxId(primary));
      assertEquals(getCurrentTxId(primary), getCurrentTxId(standby));
    }
  }

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  }
  
  protected void doTestWithStandbyDeadAfterFailover(boolean enableQJM) throws Exception {
    setUp("testWithStandbyDeadAfterFailover", enableQJM);
    // initial checkpoint 3
    AvatarNode primary = cluster.getPrimaryAvatar(0).avatar;
    
    createEdits(20); //23
    assertEquals(23, getCurrentTxId(primary));
    cluster.failOver(); //25
    primary = cluster.getPrimaryAvatar(0).avatar;
    assertEquals(25, getCurrentTxId(primary));
    createEdits(20); //45
    assertEquals(45, getCurrentTxId(primary));
    cluster.killStandby();
    createEdits(20); //65
    assertEquals(65, getCurrentTxId(primary));
    cluster.restartStandby(); //67
    Thread.sleep(1000);
    assertEquals(67, getCurrentTxId(primary));
       
    createEdits(20);


    assertEquals(87, getCurrentTxId(cluster.getPrimaryAvatar(0).avatar));
    
    AvatarNode standby = cluster.getStandbyAvatar(0).avatar;
    
    if (!enableQJM) {
      standby.quiesceStandby(getCurrentTxId(primary)-1);
      assertEquals(87, getCurrentTxId(primary));
      assertEquals(getCurrentTxId(primary), getCurrentTxId(standby));
    }
  }

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    TestAvatarTxIdsHandler h = new TestAvatarTxIdsHandler();
    InjectionHandler.set(h);
    setUp("testWithCheckPoints", enableQJM);
    // 3 (initial checkpoint)
    createEdits(20); //23
    AvatarNode primary = cluster.getPrimaryAvatar(0).avatar;
    AvatarNode standby = cluster.getStandbyAvatar(0).avatar;
    h.doCheckpoint(); //25
    createEdits(20); //45
    
    if (!enableQJM) {
      standby.quiesceStandby(getCurrentTxId(primary)-1);
      assertEquals(45, getCurrentTxId(primary));
      assertEquals(getCurrentTxId(primary), getCurrentTxId(standby));
    }
    InjectionHandler.clear();
  }

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