Reset counters on Timer thread

Author: eterekhin

src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/CounterGroup.cs

@@ -155,8 +155,6 @@ private void EnableTimer(float pollingIntervalInSeconds)
             if (_pollingIntervalInMilliseconds == 0 || pollingIntervalInSeconds * 1000 < _pollingIntervalInMilliseconds)
             {
                 _pollingIntervalInMilliseconds = (int)(pollingIntervalInSeconds * 1000);
-                ResetCounters(); // Reset statistics for counters before we start the thread.
-
                 _timeStampSinceCollectionStarted = DateTime.UtcNow;
                 _nextPollingTimeStamp = DateTime.UtcNow + new TimeSpan(0, 0, (int)pollingIntervalInSeconds);
 
@@ -165,6 +163,7 @@ private void EnableTimer(float pollingIntervalInSeconds)
                 {
                     s_pollingThreadSleepEvent = new AutoResetEvent(false);
                     s_counterGroupEnabledList = new List<CounterGroup>();
+                    s_needsResetCounterGroup = [];
                     s_pollingThread = new Thread(PollForValues)
                     {
                         IsBackground = true,
@@ -178,6 +177,11 @@ private void EnableTimer(float pollingIntervalInSeconds)
                     s_counterGroupEnabledList.Add(this);
                 }
 
+                if (!s_needsResetCounterGroup!.Contains(this))
+                {
+                    s_needsResetCounterGroup.Add(this);
+                }
+
                 // notify the polling thread that the polling interval may have changed and the sleep should
                 // be recomputed
                 s_pollingThreadSleepEvent!.Set();
@@ -189,28 +193,7 @@ private void DisableTimer()
             Debug.Assert(Monitor.IsEntered(s_counterGroupLock));
             _pollingIntervalInMilliseconds = 0;
             s_counterGroupEnabledList?.Remove(this);
-        }
-
-        private void ResetCounters()
-        {
-            lock (s_counterGroupLock) // Lock the CounterGroup
-            {
-                foreach (DiagnosticCounter counter in _counters)
-                {
-                    if (counter is IncrementingEventCounter ieCounter)
-                    {
-                        ieCounter.UpdateMetric();
-                    }
-                    else if (counter is IncrementingPollingCounter ipCounter)
-                    {
-                        ipCounter.UpdateMetric();
-                    }
-                    else if (counter is EventCounter eCounter)
-                    {
-                        eCounter.ResetStatistics();
-                    }
-                }
-            }
+            s_needsResetCounterGroup?.Remove(this);
         }
 
         private void OnTimer()
@@ -264,7 +247,7 @@ private void OnTimer()
         private static AutoResetEvent? s_pollingThreadSleepEvent;
 
         private static List<CounterGroup>? s_counterGroupEnabledList;
-
+        private static List<CounterGroup>? s_needsResetCounterGroup;
         private static void PollForValues()
         {
             AutoResetEvent? sleepEvent = null;
@@ -274,11 +257,18 @@ private static void PollForValues()
             // calling into the callbacks can cause a re-entrancy into CounterGroup.Enable()
             // and result in a deadlock. (See https://github.com/dotnet/runtime/issues/40190 for details)
             var onTimers = new List<CounterGroup>();
+            var countersToReset = new List<DiagnosticCounter>();
             while (true)
             {
                 int sleepDurationInMilliseconds = int.MaxValue;
                 lock (s_counterGroupLock)
                 {
+                    foreach (CounterGroup counterGroup in s_needsResetCounterGroup!)
+                    {
+                        countersToReset.AddRange(counterGroup._counters);
+                    }
+                    s_needsResetCounterGroup.Clear();
+
                     sleepEvent = s_pollingThreadSleepEvent;
                     foreach (CounterGroup counterGroup in s_counterGroupEnabledList!)
                     {
@@ -293,6 +283,24 @@ private static void PollForValues()
                         sleepDurationInMilliseconds = Math.Min(sleepDurationInMilliseconds, millisecondsTillNextPoll);
                     }
                 }
+
+                foreach (DiagnosticCounter counter in countersToReset)
+                {
+                    if (counter is IncrementingEventCounter ieCounter)
+                    {
+                        ieCounter.UpdateMetric();
+                    }
+                    else if (counter is IncrementingPollingCounter ipCounter)
+                    {
+                        ipCounter.UpdateMetric();
+                    }
+                    else if (counter is EventCounter eCounter)
+                    {
+                        eCounter.ResetStatistics();
+                    }
+                }
+                countersToReset.Clear();
+
                 foreach (CounterGroup onTimer in onTimers)
                 {
                     onTimer.OnTimer();