Option 2: Just cap

Author: BrennanConroy

src/Microsoft.Extensions.Logging.Abstractions/Internal/ConcurrentLruCache.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 
 namespace Microsoft.Extensions.Logging.Internal
@@ -14,16 +15,27 @@ namespace Microsoft.Extensions.Logging.Internal
     public class FormattedLogValues : IReadOnlyList<KeyValuePair<string, object>>
     {
         private const string NullFormat = "[null]";
-        private static ConcurrentLruCache<string, LogValuesFormatter> _formatters = new ConcurrentLruCache<string, LogValuesFormatter>(1024);
+        private static ConcurrentDictionary<string, LogValuesFormatter> _formatters = new ConcurrentDictionary<string, LogValuesFormatter>();
         private readonly LogValuesFormatter _formatter;
         private readonly object[] _values;
         private readonly string _originalMessage;
+        private const int MaxCachedFormatters = 1024;
 
         public FormattedLogValues(string format, params object[] values)
         {
             if (values?.Length != 0 && format != null)
             {
-                _formatter = _formatters.GetOrAdd(format, format, f => new LogValuesFormatter(f));
+                if (_formatters.Count >= MaxCachedFormatters)
+                {
+                    if (!_formatters.TryGetValue(format, out _formatter))
+                    {
+                        _formatter = new LogValuesFormatter(format);
+                    }
+                }
+                else
+                {
+                    _formatter = _formatters.GetOrAdd(format, f => new LogValuesFormatter(f));
+                }
             }
 
             _originalMessage = format ?? NullFormat;