From 2bbc3ea1b54c25c28eb04caa48dece5cfc19d613 Mon Sep 17 00:00:00 2001
From: Kihwal Lee <kihwal@apache.org>
Date: Wed, 13 Jul 2016 21:59:35 -0500
Subject: [PATCH] HDFS-10617. PendingReconstructionBlocks.size() should be
 synchronized. Contributed by Eric Badger.

---
 .../server/blockmanagement/PendingReconstructionBlocks.java   | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/PendingReconstructionBlocks.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/PendingReconstructionBlocks.java
index 956e94f4df1..6628c43a52c 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/PendingReconstructionBlocks.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/PendingReconstructionBlocks.java
@@ -134,7 +134,9 @@ class PendingReconstructionBlocks {
    * The total number of blocks that are undergoing reconstruction.
    */
   int size() {
-    return pendingReconstructions.size();
+    synchronized (pendingReconstructions) {
+      return pendingReconstructions.size();
+    }
   }
 
   /**