Restore fix for #8116

src/System.Private.CoreLib/shared/System/Threading/PortableThreadPool.HillClimbing.cs

@@ -88,8 +88,8 @@ private struct LogEntry
             private readonly Random _randomIntervalGenerator = new Random();
 
             private readonly LogEntry[] _log = new LogEntry[LogCapacity];
-            private int _logStart = 0;
-            private int _logSize = 0;
+            private int _logStart;
+            private int _logSize;
 
             public HillClimbing(int wavePeriod, int maxWaveMagnitude, double waveMagnitudeMultiplier, int waveHistorySize, double targetThroughputRatio,
                 double targetSignalToNoiseRatio, double maxChangePerSecond, double maxChangePerSample, int sampleIntervalMsLow, int sampleIntervalMsHigh,
@@ -184,8 +184,11 @@ public HillClimbing(int wavePeriod, int maxWaveMagnitude, double waveMagnitudeMu
                 // Add the current thread count and throughput sample to our history
                 //
                 double throughput = numCompletions / sampleDurationSeconds;
-
-                PortableThreadPoolEventSource.Log.WorkerThreadAdjustmentSample(throughput);
+                PortableThreadPoolEventSource log = PortableThreadPoolEventSource.Log;
+                if (log.IsEnabled())
+                {
+                    log.WorkerThreadAdjustmentSample(throughput);
+                }
 
                 int sampleIndex = (int)(_totalSamples % _samplesToMeasure);
                 _samples[sampleIndex] = throughput;
@@ -355,8 +358,11 @@ public HillClimbing(int wavePeriod, int maxWaveMagnitude, double waveMagnitudeMu
                 // Record these numbers for posterity
                 //
 
-                PortableThreadPoolEventSource.Log.WorkerThreadAdjustmentStats(sampleDurationSeconds, throughput, threadWaveComponent.Real, throughputWaveComponent.Real,
+                if (log.IsEnabled())
+                {
+                    log.WorkerThreadAdjustmentStats(sampleDurationSeconds, throughput, threadWaveComponent.Real, throughputWaveComponent.Real,
                     throughputErrorEstimate, _averageThroughputNoise, ratio.Real, confidence, _currentControlSetting, (ushort)newThreadWaveMagnitude);
+                }
 
 
                 //
@@ -413,7 +419,11 @@ private void LogTransition(int newThreadCount, double throughput, StateOrTransit
 
                 _logSize++;
 
-                PortableThreadPoolEventSource.Log.WorkerThreadAdjustmentAdjustment(throughput, newThreadCount, (int)stateOrTransition);
+                PortableThreadPoolEventSource log = PortableThreadPoolEventSource.Log;
+                if (log.IsEnabled())
+                {
+                    log.WorkerThreadAdjustmentAdjustment(throughput, newThreadCount, (int)stateOrTransition);
+                }
             }
 
             public void ForceChange(int newThreadCount, StateOrTransition state)

src/System.Private.CoreLib/shared/System/Threading/PortableThreadPool.WaitThread.cs

@@ -150,7 +150,7 @@ public CompletedWaitHandle(RegisteredWaitHandle completedHandle, bool timedOut)
             /// <summary>
             /// The number of user-registered waits on this wait thread.
             /// </summary>
-            private int _numUserWaits = 0;
+            private int _numUserWaits;
 
             /// <summary>
             /// A list of removals of wait handles that are waiting for the wait thread to process.
@@ -159,7 +159,7 @@ public CompletedWaitHandle(RegisteredWaitHandle completedHandle, bool timedOut)
             /// <summary>
             /// The number of pending removals.
             /// </summary>
-            private int _numPendingRemoves = 0;
+            private int _numPendingRemoves;
 
             /// <summary>
             /// An event to notify the wait thread that there are pending adds or removals of wait handles so it needs to wake up.

src/System.Private.CoreLib/shared/System/Threading/PortableThreadPool.WorkerThread.cs

@@ -25,7 +25,11 @@ private static int SemaphoreSpinCount
 
             private static void WorkerThreadStart()
             {
-                PortableThreadPoolEventSource.Log.WorkerThreadStart(ThreadCounts.VolatileReadCounts(ref ThreadPoolInstance._separated.counts).numExistingThreads);
+                PortableThreadPoolEventSource log = PortableThreadPoolEventSource.Log;
+                if (log.IsEnabled())
+                {
+                    log.WorkerThreadStart(ThreadCounts.VolatileReadCounts(ref ThreadPoolInstance._separated.counts).numExistingThreads);
+                }
 
                 while (true)
                 {
@@ -70,7 +74,11 @@ private static void WorkerThreadStart()
                             if (oldCounts == counts)
                             {
                                 HillClimbing.ThreadPoolHillClimber.ForceChange(newCounts.numThreadsGoal, HillClimbing.StateOrTransition.ThreadTimedOut);
-                                PortableThreadPoolEventSource.Log.WorkerThreadStop(newCounts.numExistingThreads);
+
+                                if (log.IsEnabled())
+                                {
+                                    log.WorkerThreadStop(newCounts.numExistingThreads);
+                                }
                                 return;
                             }
                         }
@@ -88,7 +96,11 @@ private static void WorkerThreadStart()
             /// <returns>If this thread was woken up before it timed out.</returns>
             private static bool WaitForRequest()
             {
-                PortableThreadPoolEventSource.Log.WorkerThreadWait(ThreadCounts.VolatileReadCounts(ref ThreadPoolInstance._separated.counts).numExistingThreads);
+                PortableThreadPoolEventSource log = PortableThreadPoolEventSource.Log;
+                if (log.IsEnabled())
+                {
+                    log.WorkerThreadWait(ThreadCounts.VolatileReadCounts(ref ThreadPoolInstance._separated.counts).numExistingThreads);
+                }
                 return s_semaphore.Wait(ThreadPoolThreadTimeoutMs);
             }
 

src/System.Private.CoreLib/shared/System/Threading/PortableThreadPool.cs

@@ -27,7 +27,7 @@ internal sealed partial class PortableThreadPool
 
         private const int CpuUtilizationHigh = 95;
         private const int CpuUtilizationLow = 80;
-        private int _cpuUtilization = 0;
+        private int _cpuUtilization;
 
         private static readonly short s_forcedMinWorkerThreads = AppContextConfigHelper.GetInt16Config("System.Threading.ThreadPool.MinThreads", 0, false);
         private static readonly short s_forcedMaxWorkerThreads = AppContextConfigHelper.GetInt16Config("System.Threading.ThreadPool.MaxThreads", 0, false);
@@ -63,7 +63,7 @@ private struct CacheLineSeparated
 
         private readonly LowLevelLock _hillClimbingThreadAdjustmentLock = new LowLevelLock();
 
-        private volatile int _numRequestedWorkers = 0;
+        private volatile int _numRequestedWorkers;
 
         private PortableThreadPool()
         {