From a7ed762428e0a31ecaa4cfa9b7b6b9b476d880c3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Lema=C5=84czyk?= <marek@lemanczyk.eu>
Date: Mon, 20 Oct 2025 01:07:02 +0200
Subject: [PATCH] Simplify scheduler configuration and pending composite
 caching

---
 .../PrimeOrderCalculator.Cpu.cs               |  4 +-
 PerfectNumbers.Core/PrimeOrderCalculator.cs   |  8 +--
 PerfectNumbers.Core/UnboundedTaskScheduler.cs | 59 ++++++-------------
 3 files changed, 23 insertions(+), 48 deletions(-)

diff --git a/PerfectNumbers.Core/PrimeOrderCalculator.Cpu.cs b/PerfectNumbers.Core/PrimeOrderCalculator.Cpu.cs
index 8f61221..5148dc0 100644
--- a/PerfectNumbers.Core/PrimeOrderCalculator.Cpu.cs
+++ b/PerfectNumbers.Core/PrimeOrderCalculator.Cpu.cs
@@ -858,13 +858,13 @@ internal static partial class PrimeOrderCalculator
 					if (currentTimestamp > deadlineTimestamp)
 					{
 						pollardRhoDeadlineReached = true;
-						pending.Add(new PendingEntry(composite, knownComposite: false).WithPrimality(false));
+						pending.Add(new PendingEntry(composite, knownComposite: true));
 						continue;
 					}
 
 					if (!TryPollardRho(composite, deadlineTimestamp, out ulong factor))
 					{
-						pending.Add(new PendingEntry(composite, knownComposite: false).WithPrimality(false));
+						pending.Add(new PendingEntry(composite, knownComposite: true));
 						continue;
 					}
 
diff --git a/PerfectNumbers.Core/PrimeOrderCalculator.cs b/PerfectNumbers.Core/PrimeOrderCalculator.cs
index 75c9cd3..d3fd7e6 100644
--- a/PerfectNumbers.Core/PrimeOrderCalculator.cs
+++ b/PerfectNumbers.Core/PrimeOrderCalculator.cs
@@ -1,3 +1,5 @@
+using System.Runtime.CompilerServices;
+
 namespace PerfectNumbers.Core;
 
 internal static partial class PrimeOrderCalculator
@@ -14,10 +16,8 @@ internal static partial class PrimeOrderCalculator
 
 		public static PrimeOrderSearchConfig HeuristicDefault
 		{
-				get
-				{
-					return _heuristicDefault;
-				}
+				[MethodImpl(MethodImplOptions.AggressiveInlining)]
+				get => _heuristicDefault;
 		}
 
 		public static readonly PrimeOrderSearchConfig StrictDefault = new(smallFactorLimit: 1_000_000, pollardRhoMilliseconds: 0, maxPowChecks: 0, PrimeOrderMode.Strict);
diff --git a/PerfectNumbers.Core/UnboundedTaskScheduler.cs b/PerfectNumbers.Core/UnboundedTaskScheduler.cs
index cbfe5fd..b552fa9 100644
--- a/PerfectNumbers.Core/UnboundedTaskScheduler.cs
+++ b/PerfectNumbers.Core/UnboundedTaskScheduler.cs
@@ -1,31 +1,18 @@
 using System;
 using System.Collections.Generic;
-using System.Threading;
 using System.Threading.Tasks;
 
 namespace PerfectNumbers.Core;
 
 public sealed class UnboundedTaskScheduler : TaskScheduler
 {
-    private static readonly object InstanceLock = new();
     private static UnboundedTaskScheduler? _instance;
     private static int _configuredThreadCount = Environment.ProcessorCount;
 
-    public static UnboundedTaskScheduler Instance
-    {
-        get
-        {
-            lock (InstanceLock)
-            {
-                _instance ??= new UnboundedTaskScheduler(GetNormalizedThreadCount(_configuredThreadCount));
-                return _instance;
-            }
-        }
-    }
+    public static UnboundedTaskScheduler Instance => _instance ??= new UnboundedTaskScheduler(_configuredThreadCount);
 
-    public static int ConfiguredThreadCount => GetNormalizedThreadCount(Volatile.Read(ref _configuredThreadCount));
+    public static int ConfiguredThreadCount => _configuredThreadCount;
 
-    private readonly object _poolLock = new();
     private TaskThreadPool _threadPool;
 
     private UnboundedTaskScheduler(int threadCount)
@@ -35,20 +22,15 @@ public sealed class UnboundedTaskScheduler : TaskScheduler
 
     public static void ConfigureThreadCount(int threadCount)
     {
-        int normalizedThreadCount = GetNormalizedThreadCount(threadCount);
+        _configuredThreadCount = threadCount;
+        PrimeOrderCalculator.PrimeOrderSearchConfig.ConfigureHeuristicDefault(threadCount);
 
-        lock (InstanceLock)
-        {
-            Volatile.Write(ref _configuredThreadCount, normalizedThreadCount);
-            PrimeOrderCalculator.PrimeOrderSearchConfig.ConfigureHeuristicDefault(normalizedThreadCount);
-
-            if (_instance is null)
-            {
-                return;
-            }
-
-            _instance.UpdateThreadPool(normalizedThreadCount);
-        }
+        // On EvenPerfectBitScanner's execution path the scheduler instance is created after configuration,
+        // so updating an existing pool would never run. Leave the update path disabled for now.
+        // if (_instance is not null)
+        // {
+        //     _instance.UpdateThreadPool(threadCount);
+        // }
     }
 
     public override int MaximumConcurrencyLevel => int.MaxValue;
@@ -60,18 +42,15 @@ public sealed class UnboundedTaskScheduler : TaskScheduler
 
     private void UpdateThreadPool(int threadCount)
     {
-        lock (_poolLock)
+        if (_threadPool.ThreadCount == threadCount)
         {
-            if (_threadPool.ThreadCount == threadCount)
-            {
-                return;
-            }
-
-            TaskThreadPool newPool = new(threadCount, ExecuteTask);
-            TaskThreadPool oldPool = _threadPool;
-            _threadPool = newPool;
-            oldPool.Dispose();
+            return;
         }
+
+        TaskThreadPool newPool = new(threadCount, ExecuteTask);
+        TaskThreadPool oldPool = _threadPool;
+        _threadPool = newPool;
+        oldPool.Dispose();
     }
 
     private void ExecuteTask(Task task)
@@ -89,8 +68,4 @@ public sealed class UnboundedTaskScheduler : TaskScheduler
         return _threadPool.GetScheduledTasks();
     }
 
-    private static int GetNormalizedThreadCount(int threadCount)
-    {
-        return threadCount < 1 ? 1 : threadCount;
-    }
 }