use WeakReference with timer, configure trim period for sandbox

src/ImageSharp/Memory/Allocators/Internals/UniformUnmanagedMemoryPool.cs

@@ -34,9 +34,10 @@ namespace SixLabors.ImageSharp.Memory.Internals
                 // Invoke the timer callback more frequently, than trimSettings.TrimPeriodMilliseconds,
                 // and also invoke it on Gen 2 GC.
                 // We are checking in the callback if enough time passed since the last trimming. If not, we do nothing.
+                var weakPoolRef = new WeakReference<UniformUnmanagedMemoryPool>(this);
                 this.trimTimer = new Timer(
-                    s => ((UniformUnmanagedMemoryPool)s)?.Trim(),
-                    this,
+                    s => TimerCallback((WeakReference<UniformUnmanagedMemoryPool>)s),
+                    weakPoolRef,
                     this.trimSettings.TrimPeriodMilliseconds / 4,
                     this.trimSettings.TrimPeriodMilliseconds / 4);
 
@@ -217,6 +218,14 @@ namespace SixLabors.ImageSharp.Memory.Internals
         private static void ThrowReturnedMoreArraysThanRented() =>
             throw new InvalidMemoryOperationException("Returned more arrays then rented");
 
+        private static void TimerCallback(WeakReference<UniformUnmanagedMemoryPool> weakPoolRef)
+        {
+            if (weakPoolRef.TryGetTarget(out UniformUnmanagedMemoryPool pool))
+            {
+                pool.Trim();
+            }
+        }
+
         private bool Trim()
         {
             UnmanagedMemoryHandle[] buffersLocal = this.buffers;
@@ -307,7 +316,7 @@ namespace SixLabors.ImageSharp.Memory.Internals
         public class TrimSettings
         {
             // Trim half of the retained pool buffers every minute.
-            public int TrimPeriodMilliseconds { get; set; } = 60_000;
+            public int TrimPeriodMilliseconds { get; set; } = 20_000;
 
             public float Rate { get; set; } = 0.5f;
 

src/ImageSharp/Memory/Allocators/UniformUnmanagedMemoryPoolMemoryAllocator.cs

@@ -18,6 +18,7 @@ namespace SixLabors.ImageSharp.Memory
         private readonly int sharedArrayPoolThresholdInBytes;
         private readonly int poolBufferSizeInBytes;
         private readonly int poolCapacity;
+        private readonly UniformUnmanagedMemoryPool.TrimSettings trimSettings;
 
         private UniformUnmanagedMemoryPool pool;
         private readonly UnmanagedMemoryAllocator nonPoolAllocator;
@@ -42,17 +43,32 @@ namespace SixLabors.ImageSharp.Memory
         {
         }
 
-        // Internal constructor allowing to change the shared array pool threshold for testing purposes.
         internal UniformUnmanagedMemoryPoolMemoryAllocator(
             int sharedArrayPoolThresholdInBytes,
             int poolBufferSizeInBytes,
             long maxPoolSizeInBytes,
             int unmanagedBufferSizeInBytes)
+            : this(
+                sharedArrayPoolThresholdInBytes,
+                poolBufferSizeInBytes,
+                maxPoolSizeInBytes,
+                unmanagedBufferSizeInBytes,
+                UniformUnmanagedMemoryPool.TrimSettings.Default)
+        {
+        }
+
+        internal UniformUnmanagedMemoryPoolMemoryAllocator(
+            int sharedArrayPoolThresholdInBytes,
+            int poolBufferSizeInBytes,
+            long maxPoolSizeInBytes,
+            int unmanagedBufferSizeInBytes,
+            UniformUnmanagedMemoryPool.TrimSettings trimSettings)
         {
             this.sharedArrayPoolThresholdInBytes = sharedArrayPoolThresholdInBytes;
             this.poolBufferSizeInBytes = poolBufferSizeInBytes;
             this.poolCapacity = (int)(maxPoolSizeInBytes / poolBufferSizeInBytes);
-            this.pool = new UniformUnmanagedMemoryPool(this.poolBufferSizeInBytes, this.poolCapacity);
+            this.trimSettings = trimSettings;
+            this.pool = new UniformUnmanagedMemoryPool(this.poolBufferSizeInBytes, this.poolCapacity, this.trimSettings);
             this.nonPoolAllocator = new UnmanagedMemoryAllocator(unmanagedBufferSizeInBytes);
         }
 
@@ -125,7 +141,7 @@ namespace SixLabors.ImageSharp.Memory
         {
             UniformUnmanagedMemoryPool oldPool = Interlocked.Exchange(
                 ref this.pool,
-                new UniformUnmanagedMemoryPool(this.poolBufferSizeInBytes, this.poolCapacity));
+                new UniformUnmanagedMemoryPool(this.poolBufferSizeInBytes, this.poolCapacity, this.trimSettings));
             oldPool.Release();
         }
 

tests/ImageSharp.Tests.ProfilingSandbox/LoadResizeSaveParallelMemoryStress.cs

@@ -11,6 +11,7 @@ using System.Threading;
 using CommandLine;
 using SixLabors.ImageSharp.Benchmarks.LoadResizeSave;
 using SixLabors.ImageSharp.Memory;
+using SixLabors.ImageSharp.Memory.Internals;
 
 namespace SixLabors.ImageSharp.Tests.ProfilingSandbox
 {
@@ -231,6 +232,9 @@ namespace SixLabors.ImageSharp.Tests.ProfilingSandbox
             [Option('f', "file", Required = false, Default = null)]
             public string FileOutput { get; set; }
 
+            [Option('t', "trim-time", Required = false, Default = 60)]
+            public int TrimTimeSeconds { get; set; }
+
             public static CommandLineOptions Parse(string[] args)
             {
                 CommandLineOptions result = null;
@@ -257,7 +261,11 @@ namespace SixLabors.ImageSharp.Tests.ProfilingSandbox
                             1024 * 1024,
                             (int)B(this.MaxContiguousPoolBufferMegaBytes),
                             B(this.MaxPoolSizeMegaBytes),
-                            (int)B(this.MaxCapacityOfUnmanagedBuffersMegaBytes));
+                            (int)B(this.MaxCapacityOfUnmanagedBuffersMegaBytes),
+                            new UniformUnmanagedMemoryPool.TrimSettings
+                            {
+                                TrimPeriodMilliseconds = this.TrimTimeSeconds * 100
+                            });
                     default:
                         throw new ArgumentOutOfRangeException();
                 }