Fix threads being cross-disposed from DatabaseContextFactory

osu.Game/Database/DatabaseContextFactory.cs

@@ -5,7 +5,6 @@
 using System.Linq;
 using System.Threading;
 using Microsoft.EntityFrameworkCore.Storage;
-using osu.Framework.Extensions.IEnumerableExtensions;
 using osu.Framework.Platform;
 
 namespace osu.Game.Database
@@ -118,7 +117,9 @@ private void usageCompleted(DatabaseWriteUsage usage)
 
         private void recycleThreadContexts()
         {
-            threadContexts?.Values.ForEach(c => c.Dispose());
+            // Contexts for other threads are not disposed as they may be in use elsewhere. Instead, fresh contexts are exposed
+            // for other threads to use, and we rely on the finalizer inside OsuDbContext to handle their previous contexts
+            threadContexts?.Value.Dispose();
             threadContexts = new ThreadLocal<OsuDbContext>(CreateContext, true);
         }
 

osu.Game/Database/OsuDbContext.cs

@@ -75,6 +75,13 @@ public OsuDbContext(string connectionString)
             }
         }
 
+        ~OsuDbContext()
+        {
+            // DbContext does not contain a finalizer (https://github.com/aspnet/EntityFrameworkCore/issues/8872)
+            // This is used to clean up previous contexts when fresh contexts are exposed via DatabaseContextFactory
+            Dispose();
+        }
+
         protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
         {
             base.OnConfiguring(optionsBuilder);