comment + rename

src/Servers/Kestrel/Core/src/Internal/Http2/Http2FrameWriter.cs

@@ -502,7 +502,7 @@ private void WriteResponseHeadersUnsynchronized(int streamId, int statusCode, Ht
             _outgoingFrame.PrepareHeaders(headerFrameFlags, streamId);
             var buffer = _headerEncodingBuffer.AsSpan();
             var done = HPackHeaderWriter.BeginEncodeHeaders(statusCode, _hpackEncoder, _headersEnumerator, buffer, out var payloadLength);
-            FinishWritingHeaders(streamId, payloadLength, done);
+            FinishWritingHeadersUnsynchronized(streamId, payloadLength, done);
         }
         // Any exception from the HPack encoder can leave the dynamic table in a corrupt state.
         // Since we allow custom header encoders we don't know what type of exceptions to expect.
@@ -543,7 +543,7 @@ private ValueTask<FlushResult> WriteDataAndTrailersAsync(Http2Stream stream, in
                 _outgoingFrame.PrepareHeaders(Http2HeadersFrameFlags.END_STREAM, streamId);
                 var buffer = _headerEncodingBuffer.AsSpan();
                 var done = HPackHeaderWriter.BeginEncodeHeaders(_hpackEncoder, _headersEnumerator, buffer, out var payloadLength);
-                FinishWritingHeaders(streamId, payloadLength, done);
+                FinishWritingHeadersUnsynchronized(streamId, payloadLength, done);
             }
             // Any exception from the HPack encoder can leave the dynamic table in a corrupt state.
             // Since we allow custom header encoders we don't know what type of exceptions to expect.
@@ -557,7 +557,7 @@ private ValueTask<FlushResult> WriteDataAndTrailersAsync(Http2Stream stream, in
         }
     }
 
-    private void FinishWritingHeaders(int streamId, int payloadLength, bool done)
+    private void FinishWritingHeadersUnsynchronized(int streamId, int payloadLength, bool done)
     {
         var buffer = _headerEncodingBuffer.AsSpan();
         _outgoingFrame.PayloadLength = payloadLength;

src/Servers/Kestrel/Core/src/Internal/Http2/Http2OutputProducer.cs

@@ -605,6 +605,8 @@ internal void OnRequestProcessingEnded()
         }
 
         // Complete outside of lock, anything this method does that needs a lock will acquire a lock itself.
+        // Additionally, this method should only be called once per Reset so calling outside of the lock is fine from the perspective
+        // of multiple threads calling OnRequestProcessingEnded.
         if (shouldCompleteStream)
         {
             Stream.CompleteStream(errored: false);
@@ -638,6 +640,8 @@ internal ValueTask<FlushResult> CompleteResponseAsync()
         }
 
         // Complete outside of lock, anything this method does that needs a lock will acquire a lock itself.
+        // CompleteResponseAsync also should never be called in parallel so calling this outside of the lock doesn't
+        // cause any weirdness with parallel threads calling this method and no longer waiting on the stream completion call.
         if (shouldCompleteStream)
         {
             Stream.CompleteStream(errored: false);