Merge pull request #240 from mlemanczyk/codex/analyze-mersenne=bydivisor-loops-for-early-breaks-kynlfe

Remove temporary by-divisor review documents

EvenPerfectBitScanner/Program.cs

@@ -104,14 +104,7 @@ internal static class Program
 				testPrimeCandidateLimit = Math.Max(1, threadCount) * 3;
 			}
 
-			if (useByDivisor)
+			_byDivisorStartPrime = useByDivisor && startPrimeProvided ? currentP : 0UL;
-			{
-				_byDivisorStartPrime = startPrimeProvided ? currentP : 0UL;
-			}
-			else
-			{
-				_byDivisorStartPrime = 0UL;
-			}
 
 			if (useByDivisor && !testMode && string.IsNullOrEmpty(filterFile))
 			{
@@ -177,10 +170,7 @@ internal static class Program
 
 			Console.WriteLine("Divisor cycles are ready");
 
-			if (useByDivisor)
+			blockSize = useByDivisor ? 1 : blockSize;
-			{
-				blockSize = 1;
-			}
 
 			CandidatesCalculator.Initialize(currentP);
 			PrimeTesters = new ThreadLocal<PrimeTester>(() => new PrimeTester(), trackAllValues: true);

PerfectNumbers.Core.Tests/Gpu/GpuPrimeLimiterTests.cs

@@ -18,22 +18,33 @@ public class GpuPrimeLimiterTests
         var startedSecond = new TaskCompletionSource<bool>();
         var sw = new Stopwatch();
 
-        using var first = GpuPrimeWorkLimiter.Acquire();
+        var first = GpuPrimeWorkLimiter.Acquire();
         sw.Start();
 
         var secondTask = Task.Run(() =>
         {
-            using var second = GpuPrimeWorkLimiter.Acquire();
+            var second = GpuPrimeWorkLimiter.Acquire();
+            try
+            {
                 startedSecond.TrySetResult(true);
+            }
+            finally
+            {
+                second.Dispose();
+            }
         });
 
+        try
+        {
             // Give secondTask a moment to attempt acquire (it should block).
             await Task.Delay(50);
             startedSecond.Task.IsCompleted.Should().BeFalse();
-
+        }
-        // Release first after short delay, allowing second to continue.
+        finally
-        // (Dispose at scope end, but we want to end now.)
+        {
+            // Release first after the initial wait so the second task can proceed.
             first.Dispose();
+        }
 
         await secondTask.WaitAsync(TimeSpan.FromSeconds(1));
         sw.Stop();

PerfectNumbers.Core.Tests/GpuWorkLimiterTests.cs

@@ -17,19 +17,31 @@ public class GpuWorkLimiterTests
         var startedSecond = new TaskCompletionSource<bool>();
         var sw = new Stopwatch();
 
-        using var first = GpuWorkLimiter.Acquire();
+        var first = GpuWorkLimiter.Acquire();
         sw.Start();
 
         var secondTask = Task.Run(() =>
         {
-            using var second = GpuWorkLimiter.Acquire();
+            var second = GpuWorkLimiter.Acquire();
+            try
+            {
                 startedSecond.TrySetResult(true);
+            }
+            finally
+            {
+                second.Dispose();
+            }
         });
 
+        try
+        {
             await Task.Delay(50);
             startedSecond.Task.IsCompleted.Should().BeFalse();
-
+        }
+        finally
+        {
             first.Dispose();
+        }
 
         await secondTask.WaitAsync(TimeSpan.FromSeconds(1));
         sw.Stop();

PerfectNumbers.Core.Tests/MersenneNumberDivisorCpuTesterTests.cs

@@ -30,7 +30,9 @@ public class MersenneNumberDivisorCpuTesterTests
                 var tester = new MersenneNumberDivisorByDivisorCpuTester();
                 tester.ConfigureFromMaxPrime(13UL);
 
-                using var session = tester.CreateDivisorSession();
+                var session = tester.CreateDivisorSession();
+                try
+                {
                         ulong[] primes = { 5UL, 7UL, 11UL, 13UL };
                         byte[] hits = new byte[primes.Length];
 
@@ -43,6 +45,11 @@ public class MersenneNumberDivisorCpuTesterTests
                         session.CheckDivisor(31UL, MontgomeryDivisorData.FromModulus(31UL), cycle31, primes, hits);
                         hits.Should().ContainInOrder(new byte[] { 1, 0, 0, 0 });
                 }
+                finally
+                {
+                        session.Dispose();
+                }
+        }
 
         [Fact]
         [Trait("Category", "Fast")]
@@ -51,7 +58,9 @@ public class MersenneNumberDivisorCpuTesterTests
                 var tester = new MersenneNumberDivisorByDivisorCpuTester();
                 tester.ConfigureFromMaxPrime(43UL);
 
-                using var session = tester.CreateDivisorSession();
+                var session = tester.CreateDivisorSession();
+                try
+                {
                         ulong[] exponents = { 6UL, 7UL, 9UL, 10UL, 12UL };
                         byte[] hits = new byte[exponents.Length];
 
@@ -61,6 +70,11 @@ public class MersenneNumberDivisorCpuTesterTests
 
                         hits.Should().Equal(new byte[] { 1, 0, 1, 0, 1 });
                 }
+                finally
+                {
+                        session.Dispose();
+                }
+        }
 
         [Fact]
         [Trait("Category", "Fast")]
@@ -69,7 +83,9 @@ public class MersenneNumberDivisorCpuTesterTests
                 var tester = new MersenneNumberDivisorByDivisorCpuTester();
                 tester.ConfigureFromMaxPrime(61UL);
 
-                using var session = tester.CreateDivisorSession();
+                var session = tester.CreateDivisorSession();
+                try
+                {
                         ulong[] exponents = { 10UL, 11UL, 20UL, 21UL, 30UL };
                         byte[] hits = new byte[exponents.Length];
 
@@ -79,5 +95,10 @@ public class MersenneNumberDivisorCpuTesterTests
 
                         hits.Should().Equal(new byte[] { 1, 0, 1, 0, 1 });
                 }
+                finally
+                {
+                        session.Dispose();
+                }
+        }
 }
 

PerfectNumbers.Core.Tests/MersenneNumberDivisorGpuTesterTests.cs

@@ -149,7 +149,9 @@ public class MersenneNumberDivisorGpuTesterTests
         var tester = new MersenneNumberDivisorByDivisorGpuTester();
         tester.ConfigureFromMaxPrime(43UL);
 
-        using var session = tester.CreateDivisorSession();
+        var session = tester.CreateDivisorSession();
+        try
+        {
             ulong[] primes = { 31UL, 37UL, 41UL };
             byte[] hits = new byte[primes.Length];
 
@@ -157,6 +159,11 @@ public class MersenneNumberDivisorGpuTesterTests
 
             hits.Should().ContainInOrder(new byte[] { 0, 1, 0 });
         }
+        finally
+        {
+            session.Dispose();
+        }
+    }
 
     [Fact]
     [Trait("Category", "Fast")]
@@ -165,7 +172,9 @@ public class MersenneNumberDivisorGpuTesterTests
         var tester = new MersenneNumberDivisorByDivisorGpuTester();
         tester.ConfigureFromMaxPrime(43UL);
 
-        using var session = tester.CreateDivisorSession();
+        var session = tester.CreateDivisorSession();
+        try
+        {
             ulong[] primes = { 31UL, 37UL, 41UL, 43UL };
             byte[] hits = new byte[primes.Length];
 
@@ -178,6 +187,11 @@ public class MersenneNumberDivisorGpuTesterTests
             session.CheckDivisor(13367UL, MontgomeryDivisorData.FromModulus(13367UL), cycle13367, primes, hits);
             hits.Should().ContainInOrder(new byte[] { 0, 0, 1, 0 });
         }
+        finally
+        {
+            session.Dispose();
+        }
+    }
 
     [Fact]
     [Trait("Category", "Fast")]
@@ -190,7 +204,9 @@ public class MersenneNumberDivisorGpuTesterTests
 
         tester.ConfigureFromMaxPrime(47UL);
 
-        using var session = tester.CreateDivisorSession();
+        var session = tester.CreateDivisorSession();
+        try
+        {
             ulong[] primes = { 31UL, 37UL, 41UL, 43UL, 47UL };
             byte[] hits = new byte[primes.Length];
 
@@ -199,6 +215,11 @@ public class MersenneNumberDivisorGpuTesterTests
 
             hits.Should().ContainInOrder(new byte[] { 0, 1, 0, 0, 0 });
         }
+        finally
+        {
+            session.Dispose();
+        }
+    }
 
     [Fact]
     [Trait("Category", "Fast")]
@@ -210,7 +231,9 @@ public class MersenneNumberDivisorGpuTesterTests
         };
         tester.ConfigureFromMaxPrime(43UL);
 
-        using var session = tester.CreateDivisorSession();
+        var session = tester.CreateDivisorSession();
+        try
+        {
             ulong[] exponents = { 6UL, 7UL, 9UL, 10UL, 12UL };
             byte[] hits = new byte[exponents.Length];
 
@@ -221,6 +244,11 @@ public class MersenneNumberDivisorGpuTesterTests
 
             hits.Should().Equal(new byte[] { 1, 0, 1, 0, 1 });
         }
+        finally
+        {
+            session.Dispose();
+        }
+    }
 
     [Fact]
     [Trait("Category", "Fast")]
@@ -232,7 +260,9 @@ public class MersenneNumberDivisorGpuTesterTests
         };
         tester.ConfigureFromMaxPrime(61UL);
 
-        using var session = tester.CreateDivisorSession();
+        var session = tester.CreateDivisorSession();
+        try
+        {
             ulong[] exponents = { 10UL, 11UL, 20UL, 21UL, 30UL };
             byte[] hits = new byte[exponents.Length];
 
@@ -243,6 +273,11 @@ public class MersenneNumberDivisorGpuTesterTests
 
             hits.Should().Equal(new byte[] { 1, 0, 1, 0, 1 });
         }
+        finally
+        {
+            session.Dispose();
+        }
+    }
 
     [Fact]
     [Trait("Category", "Fast")]
@@ -297,7 +332,9 @@ public class MersenneNumberDivisorGpuTesterTests
 
         tester.ConfigureFromMaxPrime(47UL);
 
-        using var session = tester.CreateDivisorSession();
+        var session = tester.CreateDivisorSession();
+        try
+        {
             ulong[] primes = { 31UL, 37UL, 41UL, 43UL, 47UL };
             byte[] hits = new byte[primes.Length];
 
@@ -306,5 +343,10 @@ public class MersenneNumberDivisorGpuTesterTests
 
             hits.Should().ContainInOrder(new byte[] { 0, 1, 0, 0, 0 });
         }
+        finally
+        {
+            session.Dispose();
+        }
+    }
 }
 

PerfectNumbers.Core/Cpu/MersenneCpuDivisorScanSession.cs

@@ -2,11 +2,8 @@ namespace PerfectNumbers.Core.Cpu;
 
 internal sealed class MersenneCpuDivisorScanSession : IMersenneNumberDivisorByDivisorTester.IDivisorScanSession
 {
-    private bool _disposed;
-
     public void Reset()
     {
-        _disposed = false;
     }
 
     public void CheckDivisor(
@@ -67,12 +64,6 @@ internal sealed class MersenneCpuDivisorScanSession : IMersenneNumberDivisorByDi
 
     public void Dispose()
     {
-        if (_disposed)
-        {
-            throw new ObjectDisposedException(nameof(MersenneCpuDivisorScanSession), "Divisor scan session disposed twice.");
-        }
-
-        _disposed = true;
         ThreadStaticPools.ReturnMersenneCpuDivisorSession(this);
     }
 }

PerfectNumbers.Core/Cpu/MersenneNumberDivisorByDivisorCpuTester.cs

@@ -145,14 +145,12 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
 
         byte step10;
         byte step8;
-        byte step5;
         byte step3;
         byte step7;
         byte step11;
 
         byte remainder10;
         byte remainder8;
-        byte remainder5;
         byte remainder3;
         byte remainder7;
         byte remainder11;
@@ -161,14 +159,12 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
         {
             step10 = (byte)(stepLow % 10UL);
             step8 = (byte)(stepLow & 7UL);
-            step5 = (byte)(stepLow % 5UL);
             step3 = (byte)(stepLow % 3UL);
             step7 = (byte)(stepLow % 7UL);
             step11 = (byte)(stepLow % 11UL);
 
             remainder10 = (byte)(divisorLow % 10UL);
             remainder8 = (byte)(divisorLow & 7UL);
-            remainder5 = (byte)(divisorLow % 5UL);
             remainder3 = (byte)(divisorLow % 3UL);
             remainder7 = (byte)(divisorLow % 7UL);
             remainder11 = (byte)(divisorLow % 11UL);
@@ -181,13 +177,11 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
                 decimalMask,
                 step10,
                 step8,
-                step5,
                 step3,
                 step7,
                 step11,
                 remainder10,
                 remainder8,
-                remainder5,
                 remainder3,
                 remainder7,
                 remainder11,
@@ -197,21 +191,19 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
         ulong divisorHigh = divisor.High;
         step10 = (byte)((((stepHigh % 10UL) * 6UL) + (stepLow % 10UL)) % 10UL);
         step8 = (byte)(stepLow % 8UL);
-        step5 = (byte)(((stepHigh % 5UL) + (stepLow % 5UL)) % 5UL);
         step3 = (byte)(((stepHigh % 3UL) + (stepLow % 3UL)) % 3UL);
         step7 = (byte)((((stepHigh % 7UL) * 2UL) + (stepLow % 7UL)) % 7UL);
         step11 = (byte)((((stepHigh % 11UL) * 5UL) + (stepLow % 11UL)) % 11UL);
 
         remainder10 = (byte)((((divisorHigh % 10UL) * 6UL) + (divisorLow % 10UL)) % 10UL);
         remainder8 = (byte)(divisorLow % 8UL);
-        remainder5 = (byte)(((divisorHigh % 5UL) + (divisorLow % 5UL)) % 5UL);
         remainder3 = (byte)(((divisorHigh % 3UL) + (divisorLow % 3UL)) % 3UL);
         remainder7 = (byte)((((divisorHigh % 7UL) * 2UL) + (divisorLow % 7UL)) % 7UL);
         remainder11 = (byte)((((divisorHigh % 11UL) * 5UL) + (divisorLow % 11UL)) % 11UL);
 
         while (divisor.CompareTo(limit) <= 0)
         {
-            bool passesSmallModuli = remainder3 != 0 && remainder5 != 0 && remainder7 != 0 && remainder11 != 0;
+            bool passesSmallModuli = remainder3 != 0 && remainder7 != 0 && remainder11 != 0;
             if (passesSmallModuli && (remainder8 == 1 || remainder8 == 7) && ((decimalMask >> remainder10) & 1) != 0)
             {
                 ulong candidate = divisor.Low;
@@ -261,7 +253,6 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
             divisor.Add(step);
             remainder10 = AddMod10(remainder10, step10);
             remainder8 = AddMod8(remainder8, step8);
-            remainder5 = AddMod5(remainder5, step5);
             remainder3 = AddMod3(remainder3, step3);
             remainder7 = AddMod7(remainder7, step7);
             remainder11 = AddMod11(remainder11, step11);
@@ -278,13 +269,11 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
         ushort decimalMask,
         byte step10,
         byte step8,
-        byte step5,
         byte step3,
         byte step7,
         byte step11,
         byte remainder10,
         byte remainder8,
-        byte remainder5,
         byte remainder3,
         byte remainder7,
         byte remainder11,
@@ -297,7 +286,7 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
         {
             if (divisor <= limit)
             {
-                if (remainder3 != 0 && remainder5 != 0 && remainder7 != 0 && remainder11 != 0 && (remainder8 == 1 || remainder8 == 7) && ((decimalMask >> remainder10) & 1) != 0)
+                if (remainder3 != 0 && remainder7 != 0 && remainder11 != 0 && (remainder8 == 1 || remainder8 == 7) && ((decimalMask >> remainder10) & 1) != 0)
                 {
                     MontgomeryDivisorData divisorData = MontgomeryDivisorData.FromModulus(divisor);
                     ulong divisorCycle;
@@ -345,7 +334,7 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
 
         while (true)
         {
-            bool passesSmallModuli = remainder3 != 0 && remainder5 != 0 && remainder7 != 0 && remainder11 != 0;
+            bool passesSmallModuli = remainder3 != 0 && remainder7 != 0 && remainder11 != 0;
             if (passesSmallModuli && (remainder8 == 1 || remainder8 == 7) && ((decimalMask >> remainder10) & 1) != 0)
             {
                 MontgomeryDivisorData divisorData = MontgomeryDivisorData.FromModulus(divisor);
@@ -389,7 +378,6 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
             divisor += step;
             remainder10 = AddMod10(remainder10, step10);
             remainder8 = AddMod8(remainder8, step8);
-            remainder5 = AddMod5(remainder5, step5);
             remainder3 = AddMod3(remainder3, step3);
             remainder7 = AddMod7(remainder7, step7);
             remainder11 = AddMod11(remainder11, step11);
@@ -416,19 +404,6 @@ public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDiv
         return (byte)sum;
     }
 
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private static byte AddMod5(byte value, byte delta)
-    {
-        const int Modulus = 5;
-        int sum = value + delta;
-
-        if (sum >= Modulus)
-        {
-            sum -= Modulus;
-        }
-
-        return (byte)sum;
-    }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private static byte AddMod7(byte value, byte delta)

PerfectNumbers.Core/Gpu/GpuContextPool.cs

@@ -14,8 +14,6 @@ public static class GpuContextPool
 
         internal sealed class PooledContext
         {
-                private bool disposed;
-
                 public Context Context { get; }
                 public Accelerator Accelerator { get; }
                 public bool IsCpu { get; }
@@ -34,10 +32,6 @@ public static class GpuContextPool
 
 		public void Dispose()
 		{
-			if (disposed)
-			{
-				return;
-			}
 
 			// Ensure all cached GPU buffers for this accelerator are released.
 			NttGpuMath.ClearCaches(Accelerator);
@@ -48,7 +42,6 @@ public static class GpuContextPool
 
 			Accelerator.Dispose();
 			Context.Dispose();
-			disposed = true;
 		}
 	}
 
@@ -131,7 +124,6 @@ public static class GpuContextPool
     public struct GpuContextLease
     {
         private readonly PooledContext _ctx;
-                private bool disposed;
 
                 internal GpuContextLease(PooledContext ctx, object kernelInitLock)
         {
@@ -150,13 +142,8 @@ public static class GpuContextPool
 
                 public void Dispose()
                 {
-                        if (disposed)
-			{
-				return;
-			}
 
 			Return(_ctx);
-			disposed = true;
         }
     }
 }

PerfectNumbers.Core/Gpu/GpuKernelLease.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Concurrent;
 using ILGPU;
 using ILGPU.Runtime;
@@ -9,30 +10,28 @@ public sealed class GpuKernelLease
 {
     private static readonly ConcurrentQueue<GpuKernelLease> Pool = new();
 
-    private IDisposable? _limiter;
+    private Action? _releaseLimiter;
     private GpuContextLease? _gpu;
     private KernelContainer? _kernels;
     private AcceleratorStream? _stream;
     private object? _executionLock;
-    private bool _disposed;
 
     private GpuKernelLease()
     {
     }
 
-    internal static GpuKernelLease Rent(IDisposable limiter, GpuContextLease gpu, KernelContainer kernels)
+    internal static GpuKernelLease Rent(GpuPrimeWorkLimiter.Lease limiter, GpuContextLease gpu, KernelContainer kernels)
     {
         if (!Pool.TryDequeue(out var lease))
         {
             lease = new GpuKernelLease();
         }
 
-        lease._limiter = limiter;
+        lease._releaseLimiter = limiter.Dispose;
         lease._gpu = gpu;
         lease._kernels = kernels;
         lease._stream = null;
         lease._executionLock = gpu.ExecutionLock;
-        lease._disposed = false;
         return lease;
     }
 
@@ -158,14 +157,7 @@ public sealed class GpuKernelLease
         }
     }
 
-    private void Dispose(bool disposing)
+    public void Dispose()
-    {
-        if (_disposed)
-        {
-            return;
-        }
-
-        if (disposing)
     {
         _stream?.Dispose();
         _stream = null;
@@ -175,20 +167,13 @@ public sealed class GpuKernelLease
 
         _executionLock = null;
 
-            _limiter?.Dispose();
+        _releaseLimiter?.Invoke();
-            _limiter = null;
+        _releaseLimiter = null;
-        }
 
         _kernels = null;
-        _disposed = true;
         Pool.Enqueue(this);
     }
 
-    public void Dispose()
-    {
-        Dispose(disposing: false);
-    }
-
     public readonly struct ExecutionScope
     {
         private readonly object? _lock;

PerfectNumbers.Core/Gpu/GpuPrimeWorkLimiter.cs

@@ -6,13 +6,13 @@ public static class GpuPrimeWorkLimiter
     private static readonly object _lock = new();
     private static int _currentLimit = 1;
 
-    public static IDisposable Acquire()
+    public static Lease Acquire()
     {
         // TODO: Inline the pooled limiter guard from the GpuLimiterThroughputBenchmarks so prime-sieve
-        // GPU jobs stop allocating Releaser instances on every acquisition.
+        // GPU jobs stop allocating Lease instances on every acquisition.
         var sem = _semaphore;
         sem.Wait();
-        return new Releaser(sem);
+        return new Lease(sem);
     }
 
     public static void SetLimit(int value)
@@ -36,25 +36,18 @@ public static class GpuPrimeWorkLimiter
         }
     }
 
-    private sealed class Releaser : IDisposable
+    public sealed class Lease
     {
         private readonly SemaphoreSlim _sem;
-        private bool _disposed;
 
-        public Releaser(SemaphoreSlim sem)
+        internal Lease(SemaphoreSlim sem)
         {
             _sem = sem;
         }
 
         public void Dispose()
         {
-            if (_disposed)
-            {
-                return;
-            }
-
             _sem.Release();
-            _disposed = true;
         }
     }
 }

PerfectNumbers.Core/Gpu/GpuWorkLimiter.cs

@@ -6,14 +6,14 @@ public static class GpuWorkLimiter
     private static readonly object _lock = new();
     private static int _currentLimit = 1;
 
-    public static IDisposable Acquire()
+    public static Lease Acquire()
     {
-        // TODO: Replace the per-call Releaser allocation with the pooled struct-based guard from the
+        // TODO: Replace the per-call Lease allocation with the pooled struct-based guard from the
         // GpuLimiterThroughputBenchmarks so limiter acquisition does not allocate when we enter the
         // GPU scanning hot path.
         var sem = _semaphore;
         sem.Wait();
-        return new Releaser(sem);
+        return new Lease(sem);
     }
 
     public static void SetLimit(int value)
@@ -32,7 +32,7 @@ public static class GpuWorkLimiter
 
             // Swap to a new semaphore for the new limit. We intentionally
             // do not dispose the old semaphore to avoid releasing handles
-            // that may still be in use by existing Releaser instances.
+            // that may still be in use by existing Lease instances.
             // TODO: Consolidate with GpuPrimeWorkLimiter so both limiters share a pooled SemaphoreSlim and avoid rebuilding the
             // limiter state whenever limits are adjusted from the CLI.
             _semaphore = new SemaphoreSlim(value, value);
@@ -40,25 +40,18 @@ public static class GpuWorkLimiter
         }
     }
 
-    private sealed class Releaser : IDisposable
+    public sealed class Lease
     {
         private readonly SemaphoreSlim _sem;
-        private bool _disposed;
 
-        public Releaser(SemaphoreSlim sem)
+        internal Lease(SemaphoreSlim sem)
         {
             _sem = sem;
         }
 
         public void Dispose()
         {
-            if (_disposed)
-            {
-                return;
-            }
-
             _sem.Release();
-            _disposed = true;
         }
     }
 }

PerfectNumbers.Core/Gpu/MersenneNumberDivisorByDivisorGpuTester.cs

@@ -220,7 +220,6 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
         ulong stepValue = (ulong)twoP128;
         byte step10 = (byte)(stepValue % 10UL);
         byte step8 = (byte)(stepValue & 7UL);
-        byte step5 = (byte)(stepValue % 5UL);
         byte step3 = (byte)(stepValue % 3UL);
         byte step7 = (byte)(stepValue % 7UL);
         byte step11 = (byte)(stepValue % 11UL);
@@ -229,7 +228,6 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
         ulong currentDivisorValue = (ulong)currentDivisor128;
         byte remainder10 = (byte)(currentDivisorValue % 10UL);
         byte remainder8 = (byte)(currentDivisorValue & 7UL);
-        byte remainder5 = (byte)(currentDivisorValue % 5UL);
         byte remainder3 = (byte)(currentDivisorValue % 3UL);
         byte remainder7 = (byte)(currentDivisorValue % 7UL);
         byte remainder11 = (byte)(currentDivisorValue % 11UL);
@@ -275,14 +273,13 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
 
             byte localRemainder10 = remainder10;
             byte localRemainder8 = remainder8;
-            byte localRemainder5 = remainder5;
             byte localRemainder3 = remainder3;
             byte localRemainder7 = remainder7;
             byte localRemainder11 = remainder11;
 
             for (int i = 0; i < chunkCount; i++)
             {
-                bool passesSmallModuli = localRemainder3 != 0 && localRemainder5 != 0 && localRemainder7 != 0 && localRemainder11 != 0;
+                bool passesSmallModuli = localRemainder3 != 0 && localRemainder7 != 0 && localRemainder11 != 0;
                 if (passesSmallModuli && (localRemainder8 == 1 || localRemainder8 == 7) && ((decimalMask >> localRemainder10) & 1) != 0)
                 {
                     ulong divisorValue = (ulong)nextDivisor128;
@@ -290,21 +287,16 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
                     ulong divisorCycle = ResolveDivisorCycle(divisorValue, prime, in montgomeryData);
                     if (divisorCycle == prime)
                     {
-                        int targetIndex = admissibleCount;
+                        processedCount += (ulong)(i + 1);
-                        divisorSpan[targetIndex] = divisorValue;
+                        lastProcessed = divisorValue;
-                        exponentSpan[targetIndex] = prime;
+                        coveredRange = true;
-                        divisorDataSpan[targetIndex] = new GpuDivisorPartialData(divisorValue);
+                        return true;
-                        offsetSpan[targetIndex] = targetIndex;
-                        countSpan[targetIndex] = 1;
-                        cycleSpan[targetIndex] = divisorCycle;
-                        admissibleCount++;
                     }
                 }
 
                 nextDivisor128 += twoP128;
                 localRemainder10 = AddMod10(localRemainder10, step10);
                 localRemainder8 = AddMod8(localRemainder8, step8);
-                localRemainder5 = AddMod5(localRemainder5, step5);
                 localRemainder3 = AddMod3(localRemainder3, step3);
                 localRemainder7 = AddMod7(localRemainder7, step7);
                 localRemainder11 = AddMod11(localRemainder11, step11);
@@ -312,7 +304,6 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
 
             remainder10 = localRemainder10;
             remainder8 = localRemainder8;
-            remainder5 = localRemainder5;
             remainder3 = localRemainder3;
             remainder7 = localRemainder7;
             remainder11 = localRemainder11;
@@ -380,19 +371,6 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
         return (byte)sum;
     }
 
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private static byte AddMod5(byte value, byte delta)
-    {
-        const int Modulus = 5;
-        int sum = value + delta;
-
-        if (sum >= Modulus)
-        {
-            sum -= Modulus;
-        }
-
-        return (byte)sum;
-    }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private static byte AddMod7(byte value, byte delta)
@@ -490,7 +468,6 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
         private MemoryBuffer1D<byte, Stride1D.Dense> _hitBuffer = null!;
         private ulong[] _hostBuffer = null!;
         private int _capacity;
-        private bool _disposed;
 
         internal DivisorScanSession(MersenneNumberDivisorByDivisorGpuTester owner)
         {
@@ -502,7 +479,6 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
 
         internal void Reset()
         {
-            _disposed = false;
         }
 
         private void EnsureExecutionResourcesLocked(int requiredCapacity)
@@ -549,11 +525,6 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
 
         public void CheckDivisor(ulong divisor, in MontgomeryDivisorData divisorData, ulong divisorCycle, in ReadOnlySpan<ulong> primes, Span<byte> hits)
         {
-            if (_disposed)
-            {
-                throw new ObjectDisposedException(nameof(DivisorScanSession));
-            }
-
             int length = primes.Length;
             // EvenPerfectBitScanner always supplies at least one exponent per divisor check, so the guard stays commented out.
             // if (length == 0)
@@ -622,12 +593,7 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
             int sentinel = int.MaxValue;
             firstHitView.CopyFromCPU(ref sentinel, 1);
 
-            var kernel = _kernel;
+            var kernel = _kernel!;
-            if (kernel is null)
-            {
-                Monitor.Exit(_lease.ExecutionLock);
-                throw new InvalidOperationException("GPU divisor kernel was not initialized.");
-            }
 
             kernel(1, divisorView, offsetView, countView, exponentView, cycleView, hitView, firstHitView);
 
@@ -640,12 +606,6 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
 
         public void Dispose()
         {
-            if (_disposed)
-            {
-                return;
-            }
-
-            _disposed = true;
             _owner._sessionPool.Add(this);
         }
     }
@@ -695,7 +655,7 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
 
     private void ReturnBatchResources(BatchResources resources) => _resourcePool.Add(resources);
 
-    private sealed class BatchResources : IDisposable
+    private sealed class BatchResources
     {
         private Accelerator? _accelerator;
         private MemoryBuffer1D<GpuDivisorPartialData, Stride1D.Dense>? _divisorDataBuffer;

PerfectNumbers.Core/Gpu/MersenneNumberIncrementalGpuTester.cs

@@ -47,8 +47,6 @@ public class MersenneNumberIncrementalGpuTester(GpuKernelType kernelType, bool u
         int currentSize;
         int i;
         UInt128 q = UInt128.Zero;
-        try
-        {
         while (kStart <= maxK && Volatile.Read(ref isPrime))
         {
             remaining = maxK - kStart + UInt128.One;
@@ -122,13 +120,10 @@ public class MersenneNumberIncrementalGpuTester(GpuKernelType kernelType, bool u
 
             kStart += (UInt128)currentSize;
         }
-        }
+
-        finally
-        {
         ArrayPool<ulong>.Shared.Return(orderArray);
         orderBuffer.Dispose();
         execution.Dispose();
         gpuLease.Dispose();
     }
-    }
 }

PerfectNumbers.Core/Gpu/MersenneNumberLucasLehmerGpuTester.cs

@@ -152,19 +152,13 @@ public class MersenneNumberLucasLehmerGpuTester
         }
 
         GpuUInt128[] buffer = ArrayPool<GpuUInt128>.Shared.Rent(count);
-        try
-        {
         ComputeResidues(exponents, buffer.AsSpan(0, count));
         for (int i = 0; i < count; i++)
         {
             results[i] = buffer[i].IsZero;
         }
-        }
-        finally
-        {
         ArrayPool<GpuUInt128>.Shared.Return(buffer);
     }
-    }
 
     private bool IsMersennePrimeNtt(ulong exponent, GpuUInt128 nttMod, GpuUInt128 primitiveRoot, bool runOnGpu)
     {

PerfectNumbers.Core/Gpu/MersenneNumberOrderGpuTester.cs

@@ -26,8 +26,7 @@ public class MersenneNumberOrderGpuTester(GpuKernelType kernelType, bool useGpuO
 
                 var foundBuffer = accelerator.Allocate1D<int>(1); // TODO: Replace this allocation with the pooled device buffer from GpuOrderKernelBenchmarks so repeated scans reuse the pinned staging memory instead of allocating per run.
                 exponent.Mod10_8_5_3Steps(out ulong step10, out ulong step8, out ulong step5, out ulong step3);
-                try
+
-                {
                 UInt128 remaining;
                 int currentSize;
                 int found = 0;
@@ -45,7 +44,6 @@ public class MersenneNumberOrderGpuTester(GpuKernelType kernelType, bool useGpuO
                         q0.Mod10_8_5_3(out ulong q0m10, out ulong q0m8, out ulong q0m5, out ulong q0m3);
                         var kernelArgs = new ResidueAutomatonArgs(q0m10, step10, q0m8, step8, q0m3, step3, q0m5, step5);
 
-
                         // Ensure device has small cycles table for early rejections in order kernels
                         var smallCyclesView = GpuKernelPool.EnsureSmallCyclesOnDevice(accelerator);
                         kernel(stream, currentSize, exponent, (GpuUInt128)twoP, (GpuUInt128)kStart, last, divMul,
@@ -61,13 +59,9 @@ public class MersenneNumberOrderGpuTester(GpuKernelType kernelType, bool useGpuO
 
                         kStart += (UInt128)currentSize;
                 }
-		}
+
-		finally
-		{
                 foundBuffer.Dispose();
                 execution.Dispose();
                 gpuLease.Dispose();
         }
-
-	}
 }

PerfectNumbers.Core/Gpu/MersenneNumberResidueGpuTester.cs

@@ -161,7 +161,7 @@ public class MersenneNumberResidueGpuTester(bool useGpuOrder)
     private void ReturnResources(Accelerator accelerator, ResidueResources resources) =>
         _resourcePools.GetOrAdd(accelerator, static _ => new ConcurrentBag<ResidueResources>()).Add(resources);
 
-    private sealed class ResidueResources : IDisposable
+    private sealed class ResidueResources
     {
         internal ResidueResources(Accelerator accelerator, int capacity)
         {

PerfectNumbers.Core/Gpu/NttGpuMath.cs

@@ -47,7 +47,7 @@ public static class NttGpuMath
 
     private static readonly ConcurrentDictionary<Accelerator, Action<Index1D, ArrayView<GpuUInt128>, int>> BitReverseKernelCache = new(); // TODO: Precompute bit-reversal kernels during boot so we can remove the concurrent lookup overhead flagged in the benchmarks.
 
-    private sealed class SquareCacheEntry : IDisposable
+    private sealed class SquareCacheEntry
     {
         public MemoryBuffer1D<GpuUInt128, Stride1D.Dense> Buffer { get; }
         public GpuUInt128 Root { get; }

PerfectNumbers.Core/IMersenneNumberDivisorByDivisorTester.cs

@@ -16,8 +16,10 @@ public interface IMersenneNumberDivisorByDivisorTester
 
     void PrepareCandidates(in ReadOnlySpan<ulong> primes, Span<ulong> allowedMaxValues);
 
-    public interface IDivisorScanSession : IDisposable
+    public interface IDivisorScanSession
     {
         void CheckDivisor(ulong divisor, in MontgomeryDivisorData divisorData, ulong divisorCycle, in ReadOnlySpan<ulong> primes, Span<byte> hits);
+
+        void Dispose();
     }
 }

PerfectNumbers.Core/MersenneDivisorCycles.cs

@@ -137,20 +137,31 @@ public class MersenneDivisorCycles
     {
         // Binary pairs: (ulong divisor, ulong cycle)
         using var reader = new BinaryReader(compressor, Encoding.UTF8, leaveOpen: true);
+        Stream stream = reader.BaseStream;
+        byte[] buffer = new byte[16];
         while (true)
         {
-            ulong d, c;
+            int read = 0;
-            try
+            Span<byte> span = buffer;
+            while (read < span.Length)
             {
-                d = reader.ReadUInt64();
+                int chunk = stream.Read(span[read..]);
-                c = reader.ReadUInt64();
+                if (chunk == 0)
-            }
+                {
-            catch (EndOfStreamException)
+                    if (read == 0)
                     {
                         yield break;
                     }
 
-            yield return (d, c);
+                    throw new EndOfStreamException("Incomplete divisor-cycle entry.");
+                }
+
+                read += chunk;
+            }
+
+            ulong divisor = BinaryPrimitives.ReadUInt64LittleEndian(span[..8]);
+            ulong cycle = BinaryPrimitives.ReadUInt64LittleEndian(span[8..]);
+            yield return (divisor, cycle);
         }
     }
 

PerfectNumbers.Core/MersenneNumberDivisorByDivisorTester.cs

@@ -167,14 +167,10 @@ public static class MersenneNumberDivisorByDivisorTester
 
 		if (primesToTest.Count == 0)
 		{
-			if (applyStartPrime)
+			string message = applyStartPrime
-			{
+				? $"No primes greater than or equal to {startPrime.ToString(CultureInfo.InvariantCulture)} were found for --mersenne=bydivisor."
-				Console.WriteLine($"No primes greater than or equal to {startPrime.ToString(CultureInfo.InvariantCulture)} were found for --mersenne=bydivisor.");
+				: "No prime candidates remain for --mersenne=bydivisor after filtering.";
-			}
+			Console.WriteLine(message);
-			else
-			{
-				Console.WriteLine("No prime candidates remain for --mersenne=bydivisor after filtering.");
-			}
 
 			return;
 		}

PerfectNumbers.Core/MersenneNumberTester.cs

@@ -152,8 +152,6 @@ public sealed class MersenneNumberTester(
                 var stream = gpuLease.Stream;
                 var orderKernel = gpuLease.OrderKernel!;
 
-                try
-                {
                 // Guard long-running kernels by chunking the warm-up across batches.
                 // Reuse the same ScanBatchSize knob used for scanning.
                 int batchSize = GpuConstants.ScanBatchSize;
@@ -195,14 +193,11 @@ public sealed class MersenneNumberTester(
                         orderBuffer.Dispose();
                         qBuffer.Dispose();
                 }
-                }
+
-                finally
-                {
                 execution.Dispose();
                 gpuLease.Dispose();
                 ArrayPool<UInt128>.Shared.Return(qs);
         }
-        }
 
     public bool IsMersennePrime(ulong exponent)
     {

PerfectNumbers.Core/MersennePrimeFactorTester.cs

@@ -14,7 +14,7 @@ public static class MersennePrimeFactorTester
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static bool IsPrimeFactor(ulong p, ulong q, CancellationToken ct)
     {
-        if (q < 2UL || (q & 1UL) == 0)
+        if (q < 2UL)
         {
             return false;
         }

PerfectNumbers.Core/PrimeOrderCalculator.Gpu.cs

@@ -19,22 +19,15 @@ internal static partial class PrimeOrderCalculator
                 var exponentBufferArray = ThreadStaticPools.IntPool.Rent(GpuSmallPrimeFactorSlots);
                 Span<ulong> primeBuffer = primeBufferArray.AsSpan(0, GpuSmallPrimeFactorSlots);
                 Span<int> exponentBuffer = exponentBufferArray.AsSpan(0, GpuSmallPrimeFactorSlots);
-		// primeBuffer.Clear();
-		// exponentBuffer.Clear();
                 remaining = value;
 
-		try
-		{
                 var lease = GpuKernelPool.GetKernel(useGpuOrder: true);
                 var execution = lease.EnterExecutionScope();
-			try
-			{
                 Accelerator accelerator = lease.Accelerator;
                 AcceleratorStream stream = lease.Stream;
 
                 SmallPrimeFactorTables tables = GpuKernelPool.EnsureSmallPrimeFactorTables(accelerator);
                 SmallPrimeFactorScratch scratch = GpuKernelPool.EnsureSmallPrimeFactorScratch(accelerator, GpuSmallPrimeFactorSlots);
-				// scratch.Clear();
 
                 var kernel = lease.SmallPrimeFactorKernel;
                 kernel(
@@ -68,27 +61,13 @@ internal static partial class PrimeOrderCalculator
                 {
                         ulong primeValue = primeBuffer[i];
                         int exponent = exponentBuffer[i];
-					// This will never happen in production code
-					// if (primeValue == 0UL || exponent == 0)
-					// {
-					// 	continue;
-					// }
-
                         counts.Add(primeValue, exponent);
                 }
 
-				return true;
-			}
-			finally
-			{
                 execution.Dispose();
                 lease.Dispose();
-			}
-		}
-		finally
-		{
                 ThreadStaticPools.UlongPool.Return(primeBufferArray);
                 ThreadStaticPools.IntPool.Return(exponentBufferArray);
-		}
+                return true;
         }
 }

PerfectNumbers.Core/PrimeOrderCalculator.Shared.cs

@@ -193,9 +193,7 @@ internal static partial class PrimeOrderCalculator
         // {
         //     return order;
         // }
-		FactorEntry128[]? tempArray = pool.Rent(length + 1);
+        FactorEntry128[] tempArray = pool.Rent(length + 1);
-        try
-        {
 
         Span<FactorEntry128> buffer = tempArray.AsSpan(0, length);
         factorSpan.CopyTo(buffer);
@@ -228,12 +226,8 @@ internal static partial class PrimeOrderCalculator
             }
         }
 
-            return order;
-        }
-        finally
-        {
         pool.Return(tempArray, clearArray: false);
-        }
+        return order;
     }
 
     private static bool TryConfirmOrderWide(in UInt128 prime, in UInt128 order, in MontgomeryDivisorData divisorData, in PrimeOrderSearchConfig config)

PerfectNumbers.Core/PrimeTester.cs

@@ -149,9 +149,8 @@ public sealed class PrimeTester
 
     internal static class PrimeTesterGpuContextPool
     {
-        internal sealed class PooledContext : IDisposable
+        internal sealed class PooledContext
         {
-            private bool _disposed;
 
             public Context Context { get; }
 
@@ -167,15 +166,9 @@ public sealed class PrimeTester
 
             public void Dispose()
             {
-                if (_disposed)
-                {
-                    return;
-                }
-
                 PrimeTester.ClearGpuCaches(Accelerator);
                 Accelerator.Dispose();
                 Context.Dispose();
-                _disposed = true;
             }
         }
 
@@ -209,7 +202,7 @@ public sealed class PrimeTester
             Pool.Enqueue(ctx);
         }
 
-        internal struct PrimeTesterGpuContextLease : IDisposable
+        internal struct PrimeTesterGpuContextLease
         {
             private PooledContext? _ctx;
 
@@ -224,11 +217,7 @@ public sealed class PrimeTester
 
             public void Dispose()
             {
-                if (_ctx is { } ctx)
+                Return(_ctx ?? throw new InvalidOperationException("GPU context lease is not initialized."));
-                {
-                    Return(ctx);
-                    _ctx = null;
-                }
             }
         }
     }
@@ -257,7 +246,7 @@ public sealed class PrimeTester
             DevicePrimes.View.CopyFromCPU(primes);
         }
 
-        internal sealed class ScratchBuffers : IDisposable
+        internal sealed class ScratchBuffers
         {
             public MemoryBuffer1D<ulong, Stride1D.Dense> Input { get; private set; }
             public MemoryBuffer1D<byte, Stride1D.Dense> Output { get; private set; }

PerfectNumbers.Core/TaskThreadPool.cs

@@ -6,7 +6,7 @@ using System.Threading.Tasks;
 
 namespace PerfectNumbers.Core;
 
-internal sealed class TaskThreadPool : IDisposable
+internal sealed class TaskThreadPool
 {
     private readonly struct WorkItem
     {
@@ -22,8 +22,6 @@ internal sealed class TaskThreadPool : IDisposable
     private readonly BlockingCollection<WorkItem> _pendingTasks;
     private readonly Thread[] _threads;
     private readonly Action<Task> _taskExecutor;
-    private int _disposed;
-
     public TaskThreadPool(int minimumThreads, Action<Task> taskExecutor)
     {
         if (minimumThreads <= 0)
@@ -57,22 +55,18 @@ internal sealed class TaskThreadPool : IDisposable
             throw new ArgumentNullException(nameof(task));
         }
 
-        if (Volatile.Read(ref _disposed) != 0)
-        {
-            throw new ObjectDisposedException(nameof(TaskThreadPool));
-        }
-
         try
         {
             _pendingTasks.Add(new WorkItem(task));
         }
-        catch (InvalidOperationException ex) when (Volatile.Read(ref _disposed) != 0)
+        catch (Exception ex)
+        {
+            if (ex is InvalidOperationException || ex is ObjectDisposedException)
             {
                 throw new ObjectDisposedException(nameof(TaskThreadPool), ex);
             }
-        catch (ObjectDisposedException ex)
+
-        {
+            throw;
-            throw new ObjectDisposedException(nameof(TaskThreadPool), ex);
         }
     }
 
@@ -97,11 +91,6 @@ internal sealed class TaskThreadPool : IDisposable
 
     public void Dispose()
     {
-        if (Interlocked.Exchange(ref _disposed, 1) != 0)
-        {
-            return;
-        }
-
         _pendingTasks.CompleteAdding();
 
         foreach (Thread thread in _threads)

PerfectNumbers.Core/TextFileWriter.cs

@@ -6,7 +6,7 @@ namespace PerfectNumbers.Core;
 /// <summary>
 /// Provides thread-safe file writing for both text and binary data.
 /// </summary>
-public sealed class TextFileWriter : IDisposable
+public sealed class TextFileWriter
 {
     private readonly FileStream _stream;
     private StreamWriter? _textWriter;