From b5bf3b9c3844a739ef5b2f6317480b37dd0fe47b Mon Sep 17 00:00:00 2001
From: Erick Erickson <erick@apache.org>
Date: Mon, 12 Feb 2018 19:25:13 -0800
Subject: [PATCH] SOLR-11898: ConcurrentModificationException when calling
 org.apache.solr.core.SolrInfoBean.getMetricsSnapshot

---
 solr/CHANGES.txt                                            | 3 +++
 solr/core/src/java/org/apache/solr/search/FastLRUCache.java | 4 ++--
 solr/core/src/java/org/apache/solr/search/LFUCache.java     | 4 ++--
 solr/core/src/java/org/apache/solr/search/LRUCache.java     | 4 ++--
 4 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/solr/CHANGES.txt b/solr/CHANGES.txt
index 2f6005f65f8..3a6f9054597 100644
--- a/solr/CHANGES.txt
+++ b/solr/CHANGES.txt
@@ -200,6 +200,9 @@ Bug Fixes
 * SOLR-10261: In case of in-place updates, failure in leader to follower replica update request now throws the
   follower replica in leader-initiated-recovery (Ishan Chattopadhyaya, Steve Rowe)
 
+* SOLR-11898: ConcurrentModificationException when calling org.apache.solr.core.SolrInfoBean.getMetricsSnapshot
+  (Jeff Miller via Erick Erickson)
+
 Optimizations
 ----------------------
 
diff --git a/solr/core/src/java/org/apache/solr/search/FastLRUCache.java b/solr/core/src/java/org/apache/solr/search/FastLRUCache.java
index 1cf4443c912..b2e56a81f52 100644
--- a/solr/core/src/java/org/apache/solr/search/FastLRUCache.java
+++ b/solr/core/src/java/org/apache/solr/search/FastLRUCache.java
@@ -25,7 +25,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.lang.invoke.MethodHandles;
-import java.util.HashSet;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -60,7 +60,7 @@ public class FastLRUCache<K, V> extends SolrCacheBase implements SolrCache<K,V>
   private long maxRamBytes;
 
   private MetricsMap cacheMap;
-  private Set<String> metricNames = new HashSet<>();
+  private Set<String> metricNames = ConcurrentHashMap.newKeySet();
   private MetricRegistry registry;
 
   @Override
diff --git a/solr/core/src/java/org/apache/solr/search/LFUCache.java b/solr/core/src/java/org/apache/solr/search/LFUCache.java
index f502b03600b..7d41ae343ff 100644
--- a/solr/core/src/java/org/apache/solr/search/LFUCache.java
+++ b/solr/core/src/java/org/apache/solr/search/LFUCache.java
@@ -17,7 +17,7 @@
 package org.apache.solr.search;
 
 import java.lang.invoke.MethodHandles;
-import java.util.HashSet;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -65,7 +65,7 @@ public class LFUCache<K, V> implements SolrCache<K, V> {
   private int showItems = 0;
   private Boolean timeDecay = true;
   private MetricsMap cacheMap;
-  private Set<String> metricNames = new HashSet<>();
+  private Set<String> metricNames = ConcurrentHashMap.newKeySet();
   private MetricRegistry registry;
 
   @Override
diff --git a/solr/core/src/java/org/apache/solr/search/LRUCache.java b/solr/core/src/java/org/apache/solr/search/LRUCache.java
index cbd3979155d..af05dadd7d4 100644
--- a/solr/core/src/java/org/apache/solr/search/LRUCache.java
+++ b/solr/core/src/java/org/apache/solr/search/LRUCache.java
@@ -19,7 +19,7 @@ package org.apache.solr.search;
 import java.lang.invoke.MethodHandles;
 import java.util.Collection;
 import java.util.Collections;
-import java.util.HashSet;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.Map;
@@ -87,7 +87,7 @@ public class LRUCache<K,V> extends SolrCacheBase implements SolrCache<K,V>, Acco
   private Map<K,V> map;
   private String description="LRU Cache";
   private MetricsMap cacheMap;
-  private Set<String> metricNames = new HashSet<>();
+  private Set<String> metricNames = ConcurrentHashMap.newKeySet();
   private MetricRegistry registry;
 
   private long maxRamBytes = Long.MAX_VALUE;