HBASE-26482 HMaster may clean wals that is replicating in rare cases

Author: zhengzhuobinzzb

hbase-replication/src/main/java/org/apache/hadoop/hbase/replication/ZKReplicationQueueStorage.java

@@ -379,6 +379,11 @@ public long getWALPosition(ServerName serverName, String queueId, String fileNam
     return 0;
   }
 
+  /**
+   * This implement must update the cversion of root {@link #queuesZNode}. The optimistic lock of
+   * the {@link #getAllWALs()} method is based on the cversion of root {@link #queuesZNode}.
+   * @see #getAllWALs() to show the usage of the cversion of root {@link #queuesZNode} .
+   */
   @Override
   public Pair<String, SortedSet<String>> claimQueue(ServerName sourceServerName, String queueId,
       ServerName destServerName) throws ReplicationException {
@@ -417,6 +422,12 @@ public Pair<String, SortedSet<String>> claimQueue(ServerName sourceServerName, S
       }
       // add delete op for peer
       listOfOps.add(ZKUtilOp.deleteNodeFailSilent(oldQueueNode));
+      // Append new queue id for prevent lock competition in zookeeper server.
+      String claimLockZNode = ZNodePaths.joinZNode(queuesZNode, "cversion_" + newQueueId);
+      // A trick for update the cversion of root queuesZNode .
+      // The optimistic lock of the getAllWALs() method is based on the cversion of root queuesZNode
+      listOfOps.add(ZKUtilOp.createAndFailSilent(claimLockZNode, HConstants.EMPTY_BYTE_ARRAY));
+      listOfOps.add(ZKUtilOp.deleteNodeFailSilent(claimLockZNode));
 
       LOG.trace("The multi list size is {}", listOfOps.size());
       ZKUtil.multiOrSequential(zookeeper, listOfOps, false);
@@ -505,6 +516,13 @@ protected int getQueuesZNodeCversion() throws KeeperException {
     return stat.getCversion();
   }
 
+  /**
+   * The optimistic lock of this implement is based on the cversion of root {@link #queuesZNode}.
+   * Therefore, we must update the cversion of root {@link #queuesZNode} when migrate wal nodes to
+   * other queues.
+   * @see #claimQueue(ServerName, String, ServerName) as an example of updating root
+   * {@link #queuesZNode} cversion.
+   */
   @Override
   public Set<String> getAllWALs() throws ReplicationException {
     try {

hbase-replication/src/test/java/org/apache/hadoop/hbase/replication/TestZKReplicationQueueStorage.java

@@ -206,18 +206,21 @@ public void testAddRemoveLog() throws ReplicationException {
     }
   }
 
-  // For HBASE-12865
+  // For HBASE-12865, HBASE-26482
   @Test
   public void testClaimQueueChangeCversion() throws ReplicationException, KeeperException {
     ServerName serverName1 = ServerName.valueOf("127.0.0.1", 8000, 10000);
     STORAGE.addWAL(serverName1, "1", "file");
 
-    int v0 = STORAGE.getQueuesZNodeCversion();
     ServerName serverName2 = ServerName.valueOf("127.0.0.1", 8001, 10001);
+    // Avoid claimQueue update cversion for prepare server2 rsNode.
+    STORAGE.addWAL(serverName2, "1", "file");
+
+    int v0 = STORAGE.getQueuesZNodeCversion();
     STORAGE.claimQueue(serverName1, "1", serverName2);
     int v1 = STORAGE.getQueuesZNodeCversion();
-    // cversion should increase by 1 since a child node is deleted
-    assertEquals(1, v1 - v0);
+    // cversion should be increased by claimQueue method.
+    assertTrue(v1 > v0);
   }
 
   private ZKReplicationQueueStorage createWithUnstableVersion() throws IOException {