From b6698e2a828a652e995d4cfe83d8fcd095fdeee2 Mon Sep 17 00:00:00 2001
From: Yiqun Lin <yqlin@apache.org>
Date: Tue, 9 Oct 2018 10:33:13 +0800
Subject: [PATCH] HDFS-13962. Add null check for add-replica pool to avoid lock
 acquiring. Contributed by Surendra Singh Lilhore.

(cherry picked from commit 1043795f7fe44c98a34f8ea3cea708c801c3043b)
---
 .../hdfs/server/datanode/fsdataset/impl/BlockPoolSlice.java | 6 ++++--
 .../hdfs/server/datanode/fsdataset/impl/ReplicaMap.java     | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/BlockPoolSlice.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/BlockPoolSlice.java
index b9b581fedca..4a4fef9d1fe 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/BlockPoolSlice.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/BlockPoolSlice.java
@@ -183,8 +183,10 @@ class BlockPoolSlice {
                                                      .setConf(conf)
                                                      .setInitialUsed(loadDfsUsed())
                                                      .build();
-    // initialize add replica fork join pool
-    initializeAddReplicaPool(conf);
+    if (addReplicaThreadPool == null) {
+      // initialize add replica fork join pool
+      initializeAddReplicaPool(conf);
+    }
     // Make the dfs usage to be saved during shutdown.
     shutdownHook = new Runnable() {
       @Override
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/ReplicaMap.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/ReplicaMap.java
index c630b951a81..73d3c600b9c 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/ReplicaMap.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/ReplicaMap.java
@@ -154,7 +154,7 @@ class ReplicaMap {
       if (oldReplicaInfo != null) {
         return oldReplicaInfo;
       } else {
-        set.add(replicaInfo);
+        set.addOrReplace(replicaInfo);
       }
       return replicaInfo;
     }