diff --git a/sdk/servicebus/Microsoft.Azure.ServiceBus/src/Core/MessageReceiver.cs b/sdk/servicebus/Microsoft.Azure.ServiceBus/src/Core/MessageReceiver.cs
index a50996a209177..bd97f97841c7a 100644
--- a/sdk/servicebus/Microsoft.Azure.ServiceBus/src/Core/MessageReceiver.cs
+++ b/sdk/servicebus/Microsoft.Azure.ServiceBus/src/Core/MessageReceiver.cs
@@ -1008,6 +1008,7 @@ protected override async Task OnClosingAsync()
             }
             await this.ReceiveLinkManager.CloseAsync().ConfigureAwait(false);
             await this.RequestResponseLinkManager.CloseAsync().ConfigureAwait(false);
+            this.requestResponseLockedMessages.Clear();
         }
 
         protected virtual async Task<IList<Message>> OnReceiveAsync(int maxMessageCount, TimeSpan serverWaitTime)
diff --git a/sdk/servicebus/Microsoft.Azure.ServiceBus/src/Primitives/ConcurrentExpiringSet.cs b/sdk/servicebus/Microsoft.Azure.ServiceBus/src/Primitives/ConcurrentExpiringSet.cs
index 8d5263e977cb0..9f41f3f4220b0 100644
--- a/sdk/servicebus/Microsoft.Azure.ServiceBus/src/Primitives/ConcurrentExpiringSet.cs
+++ b/sdk/servicebus/Microsoft.Azure.ServiceBus/src/Primitives/ConcurrentExpiringSet.cs
@@ -4,25 +4,30 @@
 namespace Microsoft.Azure.ServiceBus.Primitives
 {
     using System;
+    using System.Collections.Generic;
     using System.Collections.Concurrent;
+    using System.Threading;
     using System.Threading.Tasks;
 
     sealed class ConcurrentExpiringSet<TKey>
     {
         readonly ConcurrentDictionary<TKey, DateTime> dictionary;
+        readonly ICollection<KeyValuePair<TKey, DateTime>> dictionaryAsCollection;
         readonly object cleanupSynObject = new object();
+        CancellationTokenSource tokenSource = new CancellationTokenSource(); // doesn't need to be disposed because it doesn't own a timer
         bool cleanupScheduled;
-        static TimeSpan delayBetweenCleanups = TimeSpan.FromSeconds(30);
+        static readonly TimeSpan delayBetweenCleanups = TimeSpan.FromSeconds(30);
 
         public ConcurrentExpiringSet()
         {
             this.dictionary = new ConcurrentDictionary<TKey, DateTime>();
+            this.dictionaryAsCollection = dictionary;
         }
 
         public void AddOrUpdate(TKey key, DateTime expiration)
         {
             this.dictionary[key] = expiration;
-            this.ScheduleCleanup();
+            this.ScheduleCleanup(tokenSource.Token);
         }
 
         public bool Contains(TKey key)
@@ -30,7 +35,14 @@ public bool Contains(TKey key)
             return this.dictionary.TryGetValue(key, out var expiration) && expiration > DateTime.UtcNow;
         }
 
-        void ScheduleCleanup()
+        public void Clear()
+        {
+            this.tokenSource.Cancel();
+            this.dictionary.Clear();
+            this.tokenSource = new CancellationTokenSource();
+        }
+
+        void ScheduleCleanup(CancellationToken token)
         {
             lock (this.cleanupSynObject)
             {
@@ -40,28 +52,38 @@ void ScheduleCleanup()
                 }
 
                 this.cleanupScheduled = true;
-                Task.Run(async () => await this.CollectExpiredEntriesAsync().ConfigureAwait(false));
+                _ = this.CollectExpiredEntriesAsync(token);
             }
         }
 
-        async Task CollectExpiredEntriesAsync()
+        async Task CollectExpiredEntriesAsync(CancellationToken token)
         {
-            await Task.Delay(delayBetweenCleanups);
-
-            lock (this.cleanupSynObject)
+            try
             {
-                this.cleanupScheduled = false;
+                await Task.Delay(delayBetweenCleanups, token).ConfigureAwait(false);
+            }
+            catch (OperationCanceledException)
+            {
+                return;
+            }
+            finally
+            {
+                lock (this.cleanupSynObject)
+                {
+                    this.cleanupScheduled = false;
+                }
             }
 
-            foreach (var key in this.dictionary.Keys)
+            foreach (var kvp in this.dictionary)
             {
-                if (DateTime.UtcNow > this.dictionary[key])
+                var expiration = kvp.Value;
+                if (DateTime.UtcNow > expiration)
                 {
-                    this.dictionary.TryRemove(key, out _);
+                    this.dictionaryAsCollection.Remove(kvp);
                 }
             }
 
-            this.ScheduleCleanup();
+            this.ScheduleCleanup(token);
         }
     }
 }
\ No newline at end of file
diff --git a/sdk/servicebus/Microsoft.Azure.ServiceBus/tests/Primitives/ConcurrentExpiringSetTests.cs b/sdk/servicebus/Microsoft.Azure.ServiceBus/tests/Primitives/ConcurrentExpiringSetTests.cs
index 508f7a87660c3..d663bb76b7cce 100644
--- a/sdk/servicebus/Microsoft.Azure.ServiceBus/tests/Primitives/ConcurrentExpiringSetTests.cs
+++ b/sdk/servicebus/Microsoft.Azure.ServiceBus/tests/Primitives/ConcurrentExpiringSetTests.cs
@@ -27,5 +27,27 @@ public void Contains_returns_false_for_expired_entry()
             set.AddOrUpdate("testKey", DateTime.UtcNow - TimeSpan.FromSeconds(5));
             Assert.False(set.Contains("testKey"), "The set should return false for an expired entry.");
         }
+
+        [Fact]
+        public void Contains_returns_false_after_clear()
+        {
+            var set = new ConcurrentExpiringSet<string>();
+            set.AddOrUpdate("testKey", DateTime.UtcNow + TimeSpan.FromSeconds(5));
+            set.Clear();
+
+            Assert.False(set.Contains("testKey"), "The set should return false after clear.");
+        }
+
+        [Fact]
+        public void Contains_returns_false_after_clear_for_added_expired_keys()
+        {
+            var set = new ConcurrentExpiringSet<string>();
+            set.AddOrUpdate("testKey1", DateTime.UtcNow + TimeSpan.FromSeconds(5));
+            set.Clear();
+            set.AddOrUpdate("testKey2", DateTime.UtcNow - TimeSpan.FromSeconds(5));
+
+            Assert.False(set.Contains("testKey1"), "The set should return false after clear.");
+            Assert.False(set.Contains("testKey2"), "The set should return false for an expired entry.");
+        }
     }
 }
\ No newline at end of file