Photon Realtime Extensions: StripKeysWithNullValues and GC Alloc

DrZepam

Hi everyone,
In our current project, we use Photon room properties to sync entities. and i noticed some heavy GC Allocs while deep profiling the game and it always ends down to this Method.



Have anyone faced this issue before ? or attempted to fix it ?

DrZepam

Changed the implementation to reduce GC.

/// <summary>
        /// This removes all key-value pairs that have a null-reference as value.
        /// Photon properties are removed by setting their value to null.
        /// Changes the original passed IDictionary!
        /// </summary>
        /// <param name="original">The IDictionary to strip of keys with null-values.</param>
        public static List<object> keysToRemove = new List<object>(); 
        public static void StripKeysWithNullValues(this IDictionary original)
        {
            /*
             * by making keysToRemove a static variable that you clear before using. It will trigger allocations only during the warm-up phase
             * as the list needs to grow. Once it's hit the high water mark for keys you need to remove. it will not allocate further during steady-state operation.
             */
            keysToRemove.Clear();
            foreach (DictionaryEntry entry in original)
            {
                if (entry.Value == null)
                {
                    keysToRemove.Add(entry.Key);
                }
            }
            foreach (var key in keysToRemove)
            {
                original.Remove(key);
            }

            // ORIGINAL PHOTON IMPLEMENTATION 

            //object[] keys = new object[original.Count];
            //original.Keys.CopyTo(keys, 0);

            //for (int index = 0; index < keys.Length; index++)
            //{
            //    object key = keys[index];
            //    if (original[key] == null)
            //    {
            //        original.Remove(key);
            //    }
            //}
        }

Tobias

Yes, this should be better to use.
I guess you would be fine with this being used for Photon / PUN?

DrZepam

Sure

Tobias

The downside of this implementation is that it's not thread safe.
I guess we'll have to pool this.