RavenDB-23183 - ensure the cached items are cleared before returning …

…the array to the ArrayPool

src/Raven.Client/Documents/Commands/MultiGet/MultiGetCommand.cs

@@ -381,6 +381,8 @@ public void Dispose()
                 for (int i = 0; i < _size; i++)
                 {
                     Values[i].Release.Dispose();
+                    Values[i].Release = default;
+                    //Values[i].Cached = null;
                 }
                 ArrayPool<(HttpCache.ReleaseCacheItem, BlittableJsonReaderObject)>.Shared.Return(Values);
                 Values = null;

test/StressTests/Client/MultiGet.cs

@@ -0,0 +1,60 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using FastTests;
+using Raven.Tests.Core.Utils.Entities;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace StressTests.Client
+{
+    public class MultiGet : RavenTestBase
+    {
+        public MultiGet(ITestOutputHelper output) : base(output)
+        {
+        }
+
+        [Fact]
+        public async Task MultiGetCanGetFromCache()
+        {
+            var store = GetDocumentStore();
+
+            using (var bulk = store.BulkInsert())
+            {
+                for (var i = 0; i < 10_000; i++)
+                {
+                    await bulk.StoreAsync(new User { Id = $"Users/{i}", Count = i });
+                }
+            }
+
+            async Task Fetch()
+            {
+                for (var i = 0; i < 64; i++)
+                {
+                    using (var session = store.OpenAsyncSession())
+                    {
+                        var n1 = Random.Shared.Next(0, 10_000);
+                        var n2 = Random.Shared.Next(0, 10_000);
+                        session.Advanced.Lazily.LoadAsync<User>($"Users/{n1}");
+                        session.Advanced.Lazily.LoadAsync<User>($"Users/{n2}");
+                        await session.Advanced.Eagerly.ExecuteAllPendingLazyOperationsAsync();
+
+                        var loaded1 = await session.LoadAsync<User>($"Users/{n1}");
+                        Assert.Equal(n1, loaded1.Count);
+
+                        var loaded2 = await session.LoadAsync<User>($"Users/{n2}");
+                        Assert.Equal(n2, loaded2.Count);
+                    }
+                }
+            }
+
+            var tasks = new List<Task>();
+            for (var i = 0; i < 100; i++)
+            {
+                tasks.Add(Task.Run(Fetch));
+            }
+
+            await Task.WhenAll(tasks);
+        }
+    }
+}