From b3c3393c19d09240588697b69dd7a9643983d357 Mon Sep 17 00:00:00 2001
From: Allan Yang <allan163@apache.org>
Date: Thu, 18 Oct 2018 21:10:53 +0800
Subject: [PATCH] HBASE-21288 HostingServer in UnassignProcedure is not
 accurate

Signed-off-by: Allan Yang <allan163@apache.org>
---
 .../org/apache/hadoop/hbase/master/HMaster.java  | 15 +++++++++++++++
 .../master/assignment/UnassignProcedure.java     | 16 +++++++++++++++-
 2 files changed, 30 insertions(+), 1 deletion(-)

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 74ce20e69ff..af210126b52 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
@@ -74,6 +74,7 @@ import org.apache.hadoop.hbase.MetaTableAccessor;
 import org.apache.hadoop.hbase.NamespaceDescriptor;
 import org.apache.hadoop.hbase.PleaseHoldException;
 import org.apache.hadoop.hbase.ReplicationPeerNotFoundException;
+import org.apache.hadoop.hbase.ServerMetrics;
 import org.apache.hadoop.hbase.ServerName;
 import org.apache.hadoop.hbase.TableDescriptors;
 import org.apache.hadoop.hbase.TableName;
@@ -1587,6 +1588,20 @@ public class HMaster extends HRegionServer implements MasterServices {
           this.serverManager.getDeadServers());
         return false;
       }
+      Map<ServerName, ServerMetrics> onlineServers = serverManager.getOnlineServers();
+      int regionNotOnOnlineServer = 0;
+      for (RegionState regionState : assignmentManager.getRegionStates().getRegionStates()) {
+        if (regionState.isOpened() && !onlineServers
+            .containsKey(regionState.getServerName())) {
+          LOG.warn("{} 's server is not in the online server list.", regionState);
+          regionNotOnOnlineServer++;
+        }
+      }
+      if (regionNotOnOnlineServer > 0) {
+        LOG.info("Not running balancer because {} regions found not on an online server",
+            regionNotOnOnlineServer);
+        return false;
+      }
 
       if (this.cpHost != null) {
         try {
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/UnassignProcedure.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/UnassignProcedure.java
index 589b732d4f7..23b2de77604 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/UnassignProcedure.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/UnassignProcedure.java
@@ -77,6 +77,8 @@ public class UnassignProcedure extends RegionTransitionProcedure {
 
   /**
    * Where to send the unassign RPC.
+   * this one may not accurate since another RTP may change this location for
+   * the region. The hostingServer will be updated in updateTransition
    */
   protected volatile ServerName hostingServer;
   /**
@@ -198,6 +200,13 @@ public class UnassignProcedure extends RegionTransitionProcedure {
       return false;
     }
 
+    if (regionNode.getRegionLocation() != null && !regionNode
+        .getRegionLocation().equals(hostingServer)) {
+      LOG.info("HostingServer changed from {} to {} for {}", hostingServer,
+          regionNode.getRegionLocation(), this);
+      this.hostingServer = regionNode.getRegionLocation();
+    }
+
 
     // Mark the region as CLOSING.
     env.getAssignmentManager().markRegionAsClosing(regionNode);
@@ -357,7 +366,12 @@ public class UnassignProcedure extends RegionTransitionProcedure {
 
   @Override
   public ServerName getServer(final MasterProcedureEnv env) {
-    return this.hostingServer;
+    RegionStateNode node =
+        env.getAssignmentManager().getRegionStates().getRegionStateNode(this.getRegionInfo());
+    if (node == null) {
+      return null;
+    }
+    return node.getRegionLocation();
   }
 
   @Override