From 1fecaff29d35aa97fb06baf840988fb29a284835 Mon Sep 17 00:00:00 2001
From: Kevin Wikant <wikak@amazon.com>
Date: Mon, 24 Jan 2022 14:47:12 -0500
Subject: [PATCH] HDFS-16303. Fix edge case where DatanodeAdminDefaultMonitor
 doubly enqueues a DatanodeDescriptor on exception

---
 .../hdfs/server/blockmanagement/DatanodeAdminDefaultMonitor.java | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeAdminDefaultMonitor.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeAdminDefaultMonitor.java
index bb9e9efb8c4a5..21e3eb0322d3d 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeAdminDefaultMonitor.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeAdminDefaultMonitor.java
@@ -275,6 +275,7 @@ private void check() {
             + "{}.", dn, e);
         getPendingNodes().add(dn);
         toRemove.add(dn);
+        unhealthyDns.remove(dn);
       } finally {
         iterkey = dn;
       }