move initial MemoryPoolBlock2s into Gen2

Author: benaadams

src/Microsoft.AspNet.Server.Kestrel/KestrelServer.cs

@@ -9,6 +9,7 @@
 using Microsoft.AspNet.Http.Features;
 using Microsoft.AspNet.Server.Kestrel.Http;
 using Microsoft.Extensions.Logging;
+using System.Runtime;
 
 namespace Microsoft.AspNet.Server.Kestrel
 {
@@ -83,6 +84,19 @@ public void Start(RequestDelegate requestDelegate)
                 }
 
                 engine.Start(information.ThreadCount == 0 ? 1 : information.ThreadCount);
+
+                // Move all MemoryPoolBlock2 into Gen2
+                GCSettings.LargeObjectHeapCompactionMode = GCLargeObjectHeapCompactionMode.CompactOnce;
+                GC.Collect(GC.MaxGeneration, GCCollectionMode.Forced, true);
+                GC.WaitForPendingFinalizers();
+
+                GCSettings.LargeObjectHeapCompactionMode = GCLargeObjectHeapCompactionMode.CompactOnce;
+                GC.Collect(GC.MaxGeneration, GCCollectionMode.Forced, true);
+                GC.WaitForPendingFinalizers();
+
+                GCSettings.LargeObjectHeapCompactionMode = GCLargeObjectHeapCompactionMode.CompactOnce;
+                GC.Collect(GC.MaxGeneration, GCCollectionMode.Forced, true);
+
                 var atLeastOneListener = false;
 
                 foreach (var address in information.Addresses)