Fix HTTP/2 response leak. (#219)

Author: samuel-williams-shopify

lib/async/http/protocol/http2/server.rb

@@ -60,6 +60,8 @@ def each(task: Task.current)
 						@requests&.async do |task, request|
 							task.annotate("Incoming request: #{request.method} #{request.path.inspect}.")
 
+							response = nil
+							
 							task.defer_stop do
 								response = yield(request)
 							rescue
@@ -69,6 +71,11 @@ def each(task: Task.current)
 								raise
 							else
 								request.send_response(response)
+								# If send response is successful, we clear it so that we don't close it below.
+								response = nil
+							ensure
+								# If some failure occurs and we didn't send the response correctly, ensure that it's closed:
+								response&.close
 							end
 						end
 

releases.md

@@ -1,5 +1,9 @@
 # Releases
 
+## Unreleased
+
+  - Fix response body leak in HTTP/2 server when stream is reset before `send_response` completes (e.g. client-side gRPC cancellation). The response body's `close` was never called, leaking any resources tied to body lifecycle (such as `rack.response_finished` callbacks and utilization metrics).
+
 ## v0.94.1
 
   - Fix `defer_stop` usage in `HTTP1::Server`, improving server graceful shutdown behavior.

test/async/http/protocol/http2/response_close_on_stream_error.rb

@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2026, by Samuel Williams.
+
+require "async/http/protocol/http2"
+require "sus/fixtures/async/http"
+require "protocol/http/body/wrapper"
+
+describe Async::HTTP::Protocol::HTTP2 do
+	with "response body close on stream error" do
+		include Sus::Fixtures::Async::HTTP::ServerContext
+		let(:protocol) {subject}
+		
+		let(:body_closed) {Async::Variable.new}
+		
+		let(:app) do
+			variable = body_closed
+			
+			Protocol::HTTP::Middleware.for do |request|
+				inner_body = Protocol::HTTP::Body::Buffered.new(["Hello World"])
+				
+				tracking_body = Class.new(Protocol::HTTP::Body::Wrapper) do
+					define_method(:close) do |error = nil|
+						super(error)
+						variable.value = true
+					end
+				end.new(inner_body)
+				
+				if request.respond_to?(:stream) && request.stream
+					Async do
+						sleep(0.01)
+						request.stream.send_reset_stream(Protocol::HTTP2::NO_ERROR)
+					end
+					
+					sleep(0.05)
+				end
+				
+				Protocol::HTTP::Response[200, {}, tracking_body]
+			end
+		end
+		
+		it "closes the response body when the stream is reset before sending" do
+			expect do
+				response = client.get("/")
+			end.to raise_exception(Exception)
+			
+			# Wait up to 1 second for the body to be closed. Without the fix,
+			# close is never called and this times out → test failure.
+			result = Async::Task.current.with_timeout(1.0) do
+				body_closed.wait
+			rescue Async::TimeoutError
+				nil
+			end
+			
+			expect(result).to be == true
+		end
+	end
+end