Better handle event reset in LoggingService

src/Build/BackEnd/Components/Logging/LoggingService.cs

@@ -1,4 +1,4 @@
-// Licensed to the .NET Foundation under one or more agreements.
+// Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
@@ -10,12 +10,12 @@
 using System.Threading;
 using Microsoft.Build.BackEnd.Components.RequestBuilder;
 using Microsoft.Build.Evaluation;
+using Microsoft.Build.Experimental.BuildCheck;
 using Microsoft.Build.Experimental.BuildCheck.Infrastructure;
 using Microsoft.Build.Framework;
 using Microsoft.Build.Shared;
 using InternalLoggerException = Microsoft.Build.Exceptions.InternalLoggerException;
 using LoggerDescription = Microsoft.Build.Logging.LoggerDescription;
-using Microsoft.Build.Experimental.BuildCheck;
 
 #nullable disable
 
@@ -1389,7 +1389,6 @@ private void StartLoggingEventProcessing()
             _emptyQueueEvent = new ManualResetEvent(false);
             _enqueueEvent = new AutoResetEvent(false);
             _loggingEventProcessingCancellation = new CancellationTokenSource();
-
             _loggingEventProcessingThread = new Thread(LoggingEventProc);
             _loggingEventProcessingThread.Name = $"MSBuild LoggingService events queue pump: {this.GetHashCode()}";
             _loggingEventProcessingThread.IsBackground = true;
@@ -1405,27 +1404,36 @@ void LoggingEventProc()
                     if (_eventQueue.TryDequeue(out object ev))
                     {
                         LoggingEventProcessor(ev);
-                        _dequeueEvent.Set();
+                        _dequeueEvent?.Set();
                     }
                     else
                     {
-                        _emptyQueueEvent.Set();
+                        _emptyQueueEvent?.Set();
 
-                        // Wait for next event, or finish.
                         if (!completeAdding.IsCancellationRequested && _eventQueue.IsEmpty)
                         {
                             WaitHandle.WaitAny(waitHandlesForNextEvent);
                         }
 
-                        _emptyQueueEvent.Reset();
+                        lock (_lockObject)
+                        {
+                            try
+                            {
+                                _emptyQueueEvent?.Reset();
+                            }
+                            catch (ObjectDisposedException)
+                            {
+                                // Might be thrown if the event was set as null in shutdown.
+                                break;
+                            }
+                        }
                     }
                 } while (!_eventQueue.IsEmpty || !completeAdding.IsCancellationRequested);
 
-                _emptyQueueEvent.Set();
+                _emptyQueueEvent?.Set();
             }
         }
 
-
         /// <summary>
         /// Clean resources used for logging event processing queue.
         /// </summary>