Replace Enumerable.Range().Select() with direct for loops to reduce allocations

src/Nethermind/Nethermind.Network/PeerManager.cs

@@ -219,38 +219,64 @@
         private async Task RunPeerUpdateLoop()
         {
             Channel<Peer> taskChannel = Channel.CreateBounded<Peer>(1);
-            using ArrayPoolList<Task> tasks = Enumerable.Range(0, _outgoingConnectParallelism).Select(async idx =>
+            using ArrayPoolList<Task> tasks = new(_outgoingConnectParallelism);
+            for (int idx = 0; idx < _outgoingConnectParallelism; idx++)
+        {
+            tasks.Add(RunWorker(idx));
+        }
+
+        async Task RunWorker(int workerIdx)
+        {
+            await foreach (Peer peer in taskChannel.Reader.ReadAllAsync(_cancellationTokenSource.Token))
             {
-                await foreach (Peer peer in taskChannel.Reader.ReadAllAsync(_cancellationTokenSource.Token))
+                try
                 {
-                    try
-                    {
-                        await SetupOutgoingPeerConnection(peer);
-                    }
-                    catch (TaskCanceledException)
-                    {
-                        if (_logger.IsDebug) _logger.Debug($"Connect worker {idx} cancelled");
-                        break;
-                    }
-                    catch (Exception e)
+                    await SetupOutgoingPeerConnection(peer);
+                }
+                catch (TaskCanceledException)
+                {
+                    if (_logger.IsDebug) _logger.Debug($"Connect worker {workerIdx} cancelled");
+                    break;
+                }
+                catch (Exception e)
+                {
+                    if (_logger.IsError) _logger.Error($"Error setting up connection to {peer}, {e}");
+                }
+            }
+            if (_logger.IsDebug) _logger.Debug($"Connect worker {workerIdx} completed");
+        }
+                {
+                    await foreach (Peer peer in taskChannel.Reader.ReadAllAsync(_cancellationTokenSource.Token))
                     {
-                        // This is strictly speaking not related to the connection, but something outside of it.
-                        if (_logger.IsError) _logger.Error($"Error setting up connection to {peer}, {e}");
+                        try
+                        {
+                            await SetupOutgoingPeerConnection(peer);
+                        }
+                        catch (TaskCanceledException)
+                        {
+                            if (_logger.IsDebug) _logger.Debug($"Connect worker {workerIdx} cancelled");
+                            break;
+                        }
+                        catch (Exception e)
+                        {
+                            // This is strictly speaking not related to the connection, but something outside of it.
+                            if (_logger.IsError) _logger.Error($"Error setting up connection to {peer}, {e}");
+                        }
                     }
-                }
-                if (_logger.IsDebug) _logger.Debug($"Connect worker {idx} completed");
-            }).ToPooledList(_outgoingConnectParallelism);
+                    if (_logger.IsDebug) _logger.Debug($"Connect worker {workerIdx} completed");
+                }));
+            }
 
             int loopCount = 0;
             long previousActivePeersCount = 0;
             int failCount = 0;
             while (true)
             {
                 try
                 {
                     if (loopCount++ % 100 == 0)
                     {
                         if (_logger.IsTrace) _logger.Trace($"Running peer update loop {loopCount - 1} - active: {_peerPool.ActivePeerCount} | candidates : {_peerPool.PeerCount}");
                     }
 
                     try

src/Nethermind/Nethermind.Trie/BatchedTrieVisitor.cs

@@ -6,7 +6,6 @@
 using System.Buffers.Binary;
 using System.Collections.Generic;
 using System.IO;
-using System.Linq;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Threading;
@@ -146,9 +145,11 @@ public void Start(
 
         try
         {
-            using ArrayPoolListRef<Task> tasks = Enumerable.Range(0, trieVisitContext.MaxDegreeOfParallelism)
-                .Select(_ => Task.Run(BatchedThread))
-                .ToPooledListRef(trieVisitContext.MaxDegreeOfParallelism);
+            using ArrayPoolListRef<Task> tasks = new(trieVisitContext.MaxDegreeOfParallelism);
+            for (int i = 0; i < trieVisitContext.MaxDegreeOfParallelism; i++)
+            {
+                tasks.Add(Task.Run(BatchedThread));
+            }
 
             Task.WaitAll(tasks.AsSpan());
         }