Reduce collection resizing costs

src/Nethermind/Nethermind.Consensus/Processing/BlockCachePreWarmer.cs

@@ -48,6 +48,8 @@ public Task PreWarmCaches(Block suggestedBlock, Hash256? parentStateRoot, Cancel
 
     public void ClearCaches() => targetWorldState?.ClearCache();
 
+    public Task ClearCachesInBackground() => targetWorldState?.ClearCachesInBackground() ?? Task.CompletedTask;
+
     private void PreWarmCachesParallel(Block suggestedBlock, Hash256 parentStateRoot, CancellationToken cancellationToken)
     {
         if (cancellationToken.IsCancellationRequested) return;

src/Nethermind/Nethermind.Consensus/Processing/BlockProcessor.cs

@@ -51,6 +51,7 @@ public partial class BlockProcessor : IBlockProcessor
     /// to any block-specific tracers.
     /// </summary>
     protected BlockReceiptsTracer ReceiptsTracer { get; set; }
+    private readonly Func<Task, Task> _clearCaches;
 
     public BlockProcessor(
         ISpecProvider? specProvider,
@@ -78,6 +79,7 @@ public BlockProcessor(
         _preWarmer = preWarmer;
         _beaconBlockRootHandler = new BeaconBlockRootHandler();
         ReceiptsTracer = new BlockReceiptsTracer();
+        _clearCaches = _ => _preWarmer.ClearCachesInBackground();
     }
 
     public event EventHandler<BlockProcessedEventArgs>? BlockProcessed;
@@ -123,6 +125,10 @@ the previous head state.*/
                     : _preWarmer?.PreWarmCaches(suggestedBlock, preBlockStateRoot!, cancellationTokenSource.Token);
                 (Block processedBlock, TxReceipt[] receipts) = ProcessOne(suggestedBlock, options, blockTracer);
                 // Block is processed, we can cancel the prewarm task
+                if (preWarmTask is not null)
+                {
+                    preWarmTask = preWarmTask.ContinueWith(_clearCaches).Unwrap();
+                }
                 cancellationTokenSource.Cancel();
                 processedBlocks[i] = processedBlock;
 

src/Nethermind/Nethermind.Consensus/Processing/IBlockCachePreWarmer.cs

@@ -12,4 +12,5 @@ public interface IBlockCachePreWarmer
 {
     Task PreWarmCaches(Block suggestedBlock, Hash256 parentStateRoot, CancellationToken cancellationToken = default);
     void ClearCaches();
+    Task ClearCachesInBackground();
 }

src/Nethermind/Nethermind.Core/Caching/ClockCache.cs

@@ -7,14 +7,17 @@
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 
+using Nethermind.Core.Collections;
 using Nethermind.Core.Threading;
 
+using CollectionExtensions = Nethermind.Core.Collections.CollectionExtensions;
+
 namespace Nethermind.Core.Caching;
 
 public sealed class ClockCache<TKey, TValue>(int maxCapacity) : ClockCacheBase<TKey>(maxCapacity)
     where TKey : struct, IEquatable<TKey>
 {
-    private readonly ConcurrentDictionary<TKey, LruCacheItem> _cacheMap = new ConcurrentDictionary<TKey, LruCacheItem>();
+    private readonly ConcurrentDictionary<TKey, LruCacheItem> _cacheMap = new(CollectionExtensions.LockPartitions, maxCapacity);
     private readonly McsLock _lock = new();
 
     public TValue Get(TKey key)
@@ -154,7 +157,7 @@ public bool Delete(TKey key)
         using var lockRelease = _lock.Acquire();
 
         base.Clear();
-        _cacheMap.Clear();
+        _cacheMap.NoResizeClear();
     }
 
     public bool Contains(TKey key)

src/Nethermind/Nethermind.Core/Caching/ClockKeyCache.cs

@@ -7,14 +7,17 @@
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 
+using Nethermind.Core.Collections;
 using Nethermind.Core.Threading;
 
+using CollectionExtensions = Nethermind.Core.Collections.CollectionExtensions;
+
 namespace Nethermind.Core.Caching;
 
 public sealed class ClockKeyCache<TKey>(int maxCapacity) : ClockCacheBase<TKey>(maxCapacity)
     where TKey : struct, IEquatable<TKey>
 {
-    private readonly ConcurrentDictionary<TKey, int> _cacheMap = new ConcurrentDictionary<TKey, int>();
+    private readonly ConcurrentDictionary<TKey, int> _cacheMap = new(CollectionExtensions.LockPartitions, maxCapacity);
     private readonly McsLock _lock = new();
 
     public bool Get(TKey key)
@@ -128,7 +131,7 @@ public bool Delete(TKey key)
         using var lockRelease = _lock.Acquire();
 
         base.Clear();
-        _cacheMap.Clear();
+        _cacheMap.NoResizeClear();
     }
 
     public bool Contains(TKey key)

src/Nethermind/Nethermind.Core/Collections/CollectionExtensions.cs

@@ -1,12 +1,19 @@
 // SPDX-FileCopyrightText: 2022 Demerzel Solutions Limited
 // SPDX-License-Identifier: LGPL-3.0-only
 
+using System;
+using System.Collections;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.Linq.Expressions;
+using System.Reflection;
 
 namespace Nethermind.Core.Collections
 {
     public static class CollectionExtensions
     {
+        public static int LockPartitions { get; } = Environment.ProcessorCount * 16;
+
         public static void AddRange<T>(this ICollection<T> list, IEnumerable<T> items)
         {
             foreach (T item in items)
@@ -22,5 +29,62 @@ public static void AddRange<T>(this ICollection<T> list, params T[] items)
                 list.Add(items[index]);
             }
         }
+
+        public static bool NoResizeClear<TKey, TValue>(this ConcurrentDictionary<TKey, TValue>? dictionary)
+                where TKey : notnull
+        {
+            if (dictionary is null || dictionary.IsEmpty)
+            {
+                return false;
+            }
+
+            using var handle = dictionary.AcquireLock();
+
+            ClearCache<TKey, TValue>.Clear(dictionary);
+            return true;
+        }
+
+        private static class ClearCache<TKey, TValue> where TKey : notnull
+        {
+            public static readonly Action<ConcurrentDictionary<TKey, TValue>> Clear = CreateNoResizeClearExpression();
+
+            private static Action<ConcurrentDictionary<TKey, TValue>> CreateNoResizeClearExpression()
+            {
+                // Parameters
+                var dictionaryParam = Expression.Parameter(typeof(ConcurrentDictionary<TKey, TValue>), "dictionary");
+
+                // Access _tables field
+                var tablesField = typeof(ConcurrentDictionary<TKey, TValue>).GetField("_tables", BindingFlags.NonPublic | BindingFlags.Instance);
+                var tablesAccess = Expression.Field(dictionaryParam, tablesField!);
+
+                // Access _buckets and _countPerLock fields
+                var tablesType = tablesField!.FieldType;
+                var bucketsField = tablesType.GetField("_buckets", BindingFlags.NonPublic | BindingFlags.Instance);
+                var countPerLockField = tablesType.GetField("_countPerLock", BindingFlags.NonPublic | BindingFlags.Instance);
+
+                var bucketsAccess = Expression.Field(tablesAccess, bucketsField!);
+                var countPerLockAccess = Expression.Field(tablesAccess, countPerLockField!);
+
+                // Clear arrays using Array.Clear
+                var clearMethod = typeof(Array).GetMethod("Clear", new[] { typeof(Array), typeof(int), typeof(int) });
+
+                var clearBuckets = Expression.Call(clearMethod!,
+                    bucketsAccess,
+                    Expression.Constant(0),
+                    Expression.ArrayLength(bucketsAccess));
+
+                var clearCountPerLock = Expression.Call(clearMethod!,
+                    countPerLockAccess,
+                    Expression.Constant(0),
+                    Expression.ArrayLength(countPerLockAccess));
+
+                // Block to execute both clears
+                var block = Expression.Block(clearBuckets, clearCountPerLock);
+
+                // Compile the expression into a lambda
+                return Expression.Lambda<Action<ConcurrentDictionary<TKey, TValue>>>(block, dictionaryParam).Compile();
+            }
+        }
     }
 }
+

src/Nethermind/Nethermind.State/IWorldState.cs

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: LGPL-3.0-only
 
 using System;
+using System.Threading.Tasks;
 using Nethermind.Core;
 using Nethermind.Core.Collections;
 using Nethermind.Core.Crypto;
@@ -114,4 +115,6 @@ public interface IWorldState : IJournal<Snapshot>, IReadOnlyStateProvider
     ArrayPoolList<AddressAsKey>? GetAccountChanges();
 
     bool ClearCache() => false;
+
+    Task ClearCachesInBackground() => Task.CompletedTask;
 }