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Replace Enumerable.Range().Select() with direct for loops to reduce allocations #9825

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Replace Enumerable.Range().Select() with direct for loops to reduce allocations #9825

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5cd7dad
Update PeerManager.cs
0xLogicalx Nov 28, 2025
de6a0f6
Update BatchedTrieVisitor.cs
0xLogicalx Nov 28, 2025
db213ae
Update PeerManager.cs
0xLogicalx Nov 28, 2025
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39 changes: 22 additions & 17 deletions src/Nethermind/Nethermind.Network/PeerManager.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -219,27 +219,32 @@ private class CandidateSelection
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++)
{
await foreach (Peer peer in taskChannel.Reader.ReadAllAsync(_cancellationTokenSource.Token))
int workerIdx = idx;
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@LukaszRozmej LukaszRozmej Nov 28, 2025

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we can probably avoid closure with something like:

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))
    {
        try
        {
            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");
}

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@0xLogicalx 0xLogicalx Nov 28, 2025

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Thanks for the suggestion! I switched the loop to call a local RunWorker(int workerIdx) helper so each worker receives its own index instead of capturing the loop variable. This removes the closure while keeping the behavior the same.

tasks.Add(Task.Run(async () =>
{
try
{
await SetupOutgoingPeerConnection(peer);
}
catch (TaskCanceledException)
{
if (_logger.IsDebug) _logger.Debug($"Connect worker {idx} cancelled");
break;
}
catch (Exception e)
await foreach (Peer peer in taskChannel.Reader.ReadAllAsync(_cancellationTokenSource.Token))
{
// This is strictly speaking not related to the connection, but something outside of it.
if (_logger.IsError) _logger.Error($"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;
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9 changes: 5 additions & 4 deletions src/Nethermind/Nethermind.Trie/BatchedTrieVisitor.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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());
}
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