Change default buffer size for byte array based serialization.

Author: yfakariya

src/MsgPack/Serialization/MessagePackSerializer.cs

@@ -39,6 +39,8 @@ public abstract partial class MessagePackSerializer : IMessagePackSingleObjectSe
 	{
 		internal static readonly UnpackerOptions DefaultUnpackerOptions = new UnpackerOptions { ValidationLevel = UnpackerValidationLevel.None };
 
+		internal const int BufferSize = 256;
+
 		private readonly SerializationContext _ownerContext;
 
 		/// <summary>

src/MsgPack/Serialization/MessagePackSerializer`1.cs

@@ -869,7 +869,7 @@ protected internal virtual Task UnpackToAsyncCore( Unpacker unpacker, T collecti
 		public byte[] PackSingleObject( T objectTree )
 		{
 			// Packer does not have finalizer, so just avoiding unpacker disposing prevents stream closing.
-			var packer = Packer.Create( new byte[ 64 * 1024 ], this.PackerCompatibilityOptions );
+			var packer = Packer.Create( BufferManager.NewByteBuffer( BufferSize ), this.PackerCompatibilityOptions );
 
 			this.PackTo( packer, objectTree );
 			return packer.GetResultBytes();
@@ -916,7 +916,7 @@ public Task<byte[]> PackSingleObjectAsync( T objectTree )
 		public async Task<byte[]> PackSingleObjectAsync( T objectTree, CancellationToken cancellationToken )
 		{
 			// Packer does not have finalizer, so just avoiding unpacker disposing prevents stream closing.
-			var packer = Packer.Create( new byte[ 64 * 1024 ], this.PackerCompatibilityOptions );
+			var packer = Packer.Create( BufferManager.NewByteBuffer( BufferSize ), this.PackerCompatibilityOptions );
 
 			await this.PackToAsync( packer, objectTree, cancellationToken ).ConfigureAwait( false );
 			return packer.GetResultBytes();