Enable LOH Compacting on forcegc (#4101)

* Enable LOH Compacting on forcegc

Maybe this will help recover long running servers that go into GC sawtooth pattern

* This should be good for master

Source/ACE.Server/Command/Handlers/DeveloperCommands.cs

@@ -2,8 +2,9 @@
 using System.Collections.Generic;
 using System.Globalization;
 using System.Linq;
-using System.Threading.Tasks;
 using System.Numerics;
+using System.Runtime;
+using System.Threading.Tasks;
 
 using log4net;
 
@@ -2213,8 +2214,18 @@ public static void HandleClearPhysicsCaches(Session session, params string[] par
         public static void HandleForceGC(Session session, params string[] parameters)
         {
             GC.Collect();
+        }
+
+        [CommandHandler("forcegc2", AccessLevel.Developer, CommandHandlerFlag.None, 0, "Forces .NET Garbage Collection with LOH Compact")]
+        public static void HandleForceGC2(Session session, params string[] parameters)
+        {
+            // https://learn.microsoft.com/en-us/dotnet/standard/garbage-collection/fundamentals
+            // https://learn.microsoft.com/en-us/dotnet/api/system.runtime.gcsettings.largeobjectheapcompactionmode
+            GCSettings.LargeObjectHeapCompactionMode = GCLargeObjectHeapCompactionMode.CompactOnce;
+
+            GC.Collect();
 
-            CommandHandlerHelper.WriteOutputInfo(session, ".NET Garbage Collection forced");
+            CommandHandlerHelper.WriteOutputInfo(session, ".NET Garbage Collection forced with LOH Compact");
         }
 
         [CommandHandler("auditobjectmaint", AccessLevel.Developer, CommandHandlerFlag.None, 0, "Iterates over physics objects to find leaks")]

Source/ACE.Server/Program.cs

@@ -2,6 +2,7 @@
 using System.Globalization;
 using System.IO;
 using System.Reflection;
+using System.Runtime;
 using System.Runtime.InteropServices;
 using System.Threading;
 
@@ -314,8 +315,14 @@ public static void Main(string[] args)
 
             // Free up memory before the server goes online. This can free up 6 GB+ on larger servers.
             log.Info("Forcing .net garbage collection...");
-            for (int i = 0 ; i < 10 ; i++)
+            for (int i = 0; i < 10; i++)
+            {
+                // https://learn.microsoft.com/en-us/dotnet/standard/garbage-collection/fundamentals
+                // https://learn.microsoft.com/en-us/dotnet/api/system.runtime.gcsettings.largeobjectheapcompactionmode
+                GCSettings.LargeObjectHeapCompactionMode = GCLargeObjectHeapCompactionMode.CompactOnce;
+
                 GC.Collect();
+            }
 
             // This should be last
             log.Info("Initializing CommandManager...");