System.Net.Http.WinHttpHandler.StartRequestAsync assertion failed

src/libraries/System.Net.Http.WinHttpHandler/src/System/Net/Http/WinHttpHandler.cs

@@ -90,7 +90,7 @@ private Func<
         private int _maxResponseDrainSize = HttpHandlerDefaults.DefaultMaxResponseDrainSize;
         private IDictionary<string, object>? _properties; // Only create dictionary when required.
         private volatile bool _operationStarted;
-        private volatile bool _disposed;
+        private volatile int _disposed;
         private SafeWinHttpHandle? _sessionHandle;
         private readonly WinHttpAuthHelper _authHelper = new WinHttpAuthHelper();
 
@@ -539,13 +539,11 @@ public bool EnableMultipleHttp2Connections
 
         protected override void Dispose(bool disposing)
         {
-            if (!_disposed)
+            if (Interlocked.CompareExchange(ref _disposed, 1, 0) == 0)
             {
-                _disposed = true;
-
                 if (disposing && _sessionHandle != null)
                 {
-                    SafeWinHttpHandle.DisposeAndClearHandle(ref _sessionHandle);
+                    _sessionHandle.Dispose();
                 }
             }
 
@@ -1033,7 +1031,7 @@ private async Task StartRequestAsync(WinHttpRequestState state)
             }
             finally
             {
-                SafeWinHttpHandle.DisposeAndClearHandle(ref connectHandle);
+                connectHandle?.Dispose();
 
                 try
                 {
@@ -1620,7 +1618,7 @@ private void SetOperationStarted()
 
         private void CheckDisposed()
         {
-            if (_disposed)
+            if (_disposed == 1)
             {
                 throw new ObjectDisposedException(GetType().FullName);
             }