From 94a80974d39a7a3b86192d8819285275f3c9da37 Mon Sep 17 00:00:00 2001
From: Yiqun Lin <yqlin@apache.org>
Date: Mon, 6 Feb 2017 13:15:16 +0800
Subject: [PATCH] HDFS-11377. Balancer hung due to no available mover threads.
 Contributed by yunjiong zhao.

(cherry picked from commit 9cbbd1eae893b21212c9bc9e6745c6859317a667)
---
 .../org/apache/hadoop/hdfs/server/balancer/Dispatcher.java     | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/balancer/Dispatcher.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/balancer/Dispatcher.java
index 16f535e90c7..36aef8efe8a 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/balancer/Dispatcher.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/balancer/Dispatcher.java
@@ -86,7 +86,6 @@ import com.google.common.base.Preconditions;
 public class Dispatcher {
   static final Log LOG = LogFactory.getLog(Dispatcher.class);
 
-  private static final int MAX_NO_PENDING_MOVE_ITERATIONS = 5;
   /**
    * the period of time to delay the usage of a DataNode after hitting
    * errors when using it for migrating data
@@ -1032,6 +1031,8 @@ public class Dispatcher {
     }
     if (moveExecutor == null) {
       LOG.warn("No mover threads available: skip moving " + p);
+      targetDn.removePendingBlock(p);
+      p.proxySource.removePendingBlock(p);
       return;
     }