From 1f30506d20638361fd6a21607e2c132933759554 Mon Sep 17 00:00:00 2001
From: Ye Ni <141253+NickyYe@users.noreply.github.com>
Date: Thu, 17 Dec 2020 16:53:59 -0800
Subject: [PATCH] Update DatanodeAdminManager.java

---
 .../blockmanagement/DatanodeAdminManager.java | 21 +++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeAdminManager.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeAdminManager.java
index 4cd97344d73f7..30c6c67d8c8e3 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeAdminManager.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeAdminManager.java
@@ -289,6 +289,21 @@ public void startMaintenance(DatanodeDescriptor node,
    */
   @VisibleForTesting
   public void stopMaintenance(DatanodeDescriptor node) {
+    stopMaintenance(node, true);
+  }
+
+  /**
+   * Stop maintenance of the specified datanode with option to remove it from
+   * outOfServiceNodeBlocks to avoid ConcurrentModificationException while
+   * iterating it.
+   *
+   * @param node datanode to stop maintenance
+   * @param removeOutOfServiceNodeBlocks false means the node won't be removed
+   *                                     from outOfServiceNodeBlocks. Caller
+   *                                     will do that.
+   */
+  private void stopMaintenance(DatanodeDescriptor node,
+      boolean removeOutOfServiceNodeBlocks) {
     if (node.isMaintenance()) {
       // Update DN stats maintained by HeartbeatManager
       hbManager.stopMaintenance(node);
@@ -324,7 +339,9 @@ public void stopMaintenance(DatanodeDescriptor node) {
 
       // Remove from tracking in DatanodeAdminManager
       pendingNodes.remove(node);
-      outOfServiceNodeBlocks.remove(node);
+      if (removeOutOfServiceNodeBlocks) {
+        outOfServiceNodeBlocks.remove(node);
+      }
     } else {
       LOG.trace("stopMaintenance: Node {} in {}, nothing to do." +
           node, node.getAdminState());
@@ -556,7 +573,7 @@ private void check() {
           boolean fullScan = false;
           if (dn.isMaintenance() && dn.maintenanceExpired()) {
             // If maintenance expires, stop tracking it.
-            stopMaintenance(dn);
+            stopMaintenance(dn, false);
             toRemove.add(dn);
             continue;
           }