diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/ActiveMasterManager.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/ActiveMasterManager.java index 50798ed60a0..99cab625b85 100644 --- a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/ActiveMasterManager.java +++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/ActiveMasterManager.java @@ -1,4 +1,4 @@ -/** +/* * * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file @@ -17,25 +17,24 @@ * limitations under the License. */ package org.apache.hadoop.hbase.master; - import java.io.IOException; +import java.util.Optional; import java.util.concurrent.atomic.AtomicBoolean; - -import org.apache.hadoop.hbase.zookeeper.MasterAddressTracker; -import org.apache.hadoop.hbase.zookeeper.ZKUtil; -import org.apache.hadoop.hbase.zookeeper.ZKWatcher; -import org.apache.hadoop.hbase.zookeeper.ZNodePaths; -import org.apache.yetus.audience.InterfaceAudience; import org.apache.hadoop.hbase.Server; import org.apache.hadoop.hbase.ServerName; import org.apache.hadoop.hbase.ZNodeClearer; import org.apache.hadoop.hbase.exceptions.DeserializationException; import org.apache.hadoop.hbase.monitoring.MonitoredTask; -import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil; +import org.apache.hadoop.hbase.zookeeper.MasterAddressTracker; import org.apache.hadoop.hbase.zookeeper.ZKListener; +import org.apache.hadoop.hbase.zookeeper.ZKUtil; +import org.apache.hadoop.hbase.zookeeper.ZKWatcher; +import org.apache.hadoop.hbase.zookeeper.ZNodePaths; +import org.apache.yetus.audience.InterfaceAudience; import org.apache.zookeeper.KeeperException; import org.slf4j.Logger; import org.slf4j.LoggerFactory; +import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil; /** * Handles everything on master-side related to master election. @@ -57,12 +56,18 @@ public class ActiveMasterManager extends ZKListener { final AtomicBoolean clusterHasActiveMaster = new AtomicBoolean(false); final AtomicBoolean clusterShutDown = new AtomicBoolean(false); + // This server's information. private final ServerName sn; private int infoPort; private final Server master; + // Active master's server name. Invalidated anytime active master changes (based on ZK + // notifications) and lazily fetched on-demand. + // ServerName is immutable, so we don't need heavy synchronization around it. + private volatile ServerName activeMasterServerName; + /** - * @param watcher + * @param watcher ZK watcher * @param sn ServerName * @param master In an instance of a Master. */ @@ -106,6 +111,30 @@ public class ActiveMasterManager extends ZKListener { } } + /** + * Fetches the active master's ServerName from zookeeper. + */ + private void fetchAndSetActiveMasterServerName() { + LOG.debug("Attempting to fetch active master sn from zk"); + try { + activeMasterServerName = MasterAddressTracker.getMasterAddress(watcher); + } catch (IOException | KeeperException e) { + // Log and ignore for now and re-fetch later if needed. + LOG.error("Error fetching active master information", e); + } + } + + public Optional getActiveMasterServerName() { + if (!clusterHasActiveMaster.get()) { + return Optional.empty(); + } + if (activeMasterServerName == null) { + fetchAndSetActiveMasterServerName(); + } + // It could still be null, but return whatever we have. + return Optional.ofNullable(activeMasterServerName); + } + /** * Handle a change in the master node. Doesn't matter whether this was called * from a nodeCreated or nodeDeleted event because there are no guarantees @@ -134,6 +163,9 @@ public class ActiveMasterManager extends ZKListener { // Notify any thread waiting to become the active master clusterHasActiveMaster.notifyAll(); } + // Reset the active master sn. Will be re-fetched later if needed. + // We don't want to make a synchronous RPC under a monitor. + activeMasterServerName = null; } } catch (KeeperException ke) { master.abort("Received an unexpected KeeperException, aborting", ke); @@ -151,8 +183,8 @@ public class ActiveMasterManager extends ZKListener { * @param checkInterval the interval to check if the master is stopped * @param startupStatus the monitor status to track the progress * @return True if no issue becoming active master else false if another - * master was running or if some other problem (zookeeper, stop flag has been - * set on this Master) + * master was running or if some other problem (zookeeper, stop flag has been + * set on this Master) */ boolean blockUntilBecomingActiveMaster( int checkInterval, MonitoredTask startupStatus) { @@ -178,10 +210,14 @@ public class ActiveMasterManager extends ZKListener { // We are the master, return startupStatus.setStatus("Successfully registered as active master."); this.clusterHasActiveMaster.set(true); + activeMasterServerName = sn; LOG.info("Registered as active master=" + this.sn); return true; } + // Invalidate the active master name so that subsequent requests do not get any stale + // master information. Will be re-fetched if needed. + activeMasterServerName = null; // There is another active master running elsewhere or this is a restart // and the master ephemeral node has not expired yet. this.clusterHasActiveMaster.set(true); @@ -208,7 +244,8 @@ public class ActiveMasterManager extends ZKListener { ZKUtil.deleteNode(this.watcher, this.watcher.getZNodePaths().masterAddressZNode); // We may have failed to delete the znode at the previous step, but - // we delete the file anyway: a second attempt to delete the znode is likely to fail again. + // we delete the file anyway: a second attempt to delete the znode is likely to fail + // again. ZNodeClearer.deleteMyEphemeralNodeOnDisk(); } else { msg = "Another master is the active master, " + currentMaster + diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java index cf5bb0959cc..592d361685c 100644 --- a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java +++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java @@ -3827,6 +3827,10 @@ public class HMaster extends HRegionServer implements MasterServices { return cachedClusterId.getFromCacheOrFetch(); } + public Optional getActiveMaster() { + return activeMasterManager.getActiveMasterServerName(); + } + @Override public void runReplicationBarrierCleaner() { ReplicationBarrierCleaner rbc = this.replicationBarrierCleaner; diff --git a/hbase-server/src/test/java/org/apache/hadoop/hbase/master/TestActiveMasterManager.java b/hbase-server/src/test/java/org/apache/hadoop/hbase/master/TestActiveMasterManager.java index 4649eea5ce0..84837f93965 100644 --- a/hbase-server/src/test/java/org/apache/hadoop/hbase/master/TestActiveMasterManager.java +++ b/hbase-server/src/test/java/org/apache/hadoop/hbase/master/TestActiveMasterManager.java @@ -17,6 +17,7 @@ */ package org.apache.hadoop.hbase.master; +import static org.junit.Assert.assertEquals; import static org.junit.Assert.assertFalse; import static org.junit.Assert.assertNotNull; import static org.junit.Assert.assertTrue; @@ -91,6 +92,7 @@ public class TestActiveMasterManager { ActiveMasterManager activeMasterManager = dummyMaster.getActiveMasterManager(); assertFalse(activeMasterManager.clusterHasActiveMaster.get()); + assertFalse(activeMasterManager.getActiveMasterServerName().isPresent()); // First test becoming the active master uninterrupted MonitoredTask status = Mockito.mock(MonitoredTask.class); @@ -99,6 +101,7 @@ public class TestActiveMasterManager { activeMasterManager.blockUntilBecomingActiveMaster(100, status); assertTrue(activeMasterManager.clusterHasActiveMaster.get()); assertMaster(zk, master); + assertMaster(zk, activeMasterManager.getActiveMasterServerName().get()); // Now pretend master restart DummyMaster secondDummyMaster = new DummyMaster(zk,master); @@ -108,6 +111,8 @@ public class TestActiveMasterManager { activeMasterManager.blockUntilBecomingActiveMaster(100, status); assertTrue(activeMasterManager.clusterHasActiveMaster.get()); assertMaster(zk, master); + assertMaster(zk, activeMasterManager.getActiveMasterServerName().get()); + assertMaster(zk, secondActiveMasterManager.getActiveMasterServerName().get()); } /** @@ -135,6 +140,7 @@ public class TestActiveMasterManager { ActiveMasterManager activeMasterManager = ms1.getActiveMasterManager(); assertFalse(activeMasterManager.clusterHasActiveMaster.get()); + assertFalse(activeMasterManager.getActiveMasterServerName().isPresent()); // First test becoming the active master uninterrupted ClusterStatusTracker clusterStatusTracker = @@ -144,6 +150,7 @@ public class TestActiveMasterManager { Mockito.mock(MonitoredTask.class)); assertTrue(activeMasterManager.clusterHasActiveMaster.get()); assertMaster(zk, firstMasterAddress); + assertMaster(zk, activeMasterManager.getActiveMasterServerName().get()); // New manager will now try to become the active master in another thread WaitToBeMasterThread t = new WaitToBeMasterThread(zk, secondMasterAddress); @@ -161,6 +168,8 @@ public class TestActiveMasterManager { assertTrue(t.manager.clusterHasActiveMaster.get()); // But secondary one should not be the active master assertFalse(t.isActiveMaster); + // Verify the active master ServerName is populated in standby master. + assertEquals(firstMasterAddress, t.manager.getActiveMasterServerName().get()); // Close the first server and delete it's master node ms1.stop("stopping first server"); @@ -189,6 +198,7 @@ public class TestActiveMasterManager { assertTrue(t.manager.clusterHasActiveMaster.get()); assertTrue(t.isActiveMaster); + assertEquals(secondMasterAddress, t.manager.getActiveMasterServerName().get()); LOG.info("Deleting master node");