@@ -5,7 +5,7 @@
 """
 
 from http.server import BaseHTTPRequestHandler, HTTPServer, HTTPSServer, \
-     SimpleHTTPRequestHandler, ThreadingHTTPServer
+     SimpleHTTPRequestHandler
 from http import server, HTTPStatus
 
 import contextlib
@@ -965,82 +965,6 @@ def test_multiple_requests_dont_duplicate_extra_response_headers(self):
             self.assertEqual(response.status, 200)
             self.assertEqual(response.getheader("x-test"), 'test-value')
 
-    def test_extra_response_headers_concurrent_requests(self):
-        N_THREADS = 8
-
-        with mock.patch.object(
-            self.request_handler,
-            "extra_response_headers",
-            [("x-test", "test-value")],
-        ):
-            threaded_server = ThreadingHTTPServer(
-                ("localhost", 0), self.request_handler
-            )
-            host, port = threaded_server.socket.getsockname()
-            server_thread = threading.Thread(
-                target=threaded_server.serve_forever, args=(0.05,), daemon=True
-            )
-            # Clean up the server thread and server resources after the test,
-            # with a timeout to prevent hanging, even if the finally block fails.
-            self.addCleanup(server_thread.join, support.SHORT_TIMEOUT)
-            self.addCleanup(threaded_server.server_close)
-            self.addCleanup(threaded_server.shutdown)
-            server_thread.start()
-            results = []
-            errors = []
-            lock = threading.Lock()
-
-            def make_request():
-                try:
-                    conn = http.client.HTTPConnection(host, port, timeout=15)
-                    conn.request("GET", self.base_url + "/")
-                    resp = conn.getresponse()
-                    resp.read()
-                    with lock:
-                        results.append((resp.status, resp.getheaders()))
-                    conn.close()
-                except Exception as e:
-                    # Catch exceptions in child threads and save them.
-                    with lock:
-                        errors.append(e)
-
-            try:
-                threads = [
-                    threading.Thread(target=make_request)
-                    for _ in range(N_THREADS)
-                ]
-                for t in threads:
-                    t.start()
-                for t in threads:
-                    t.join(timeout=15)
-            finally:
-                threaded_server.shutdown()
-                threaded_server.server_close()
-                server_thread.join(timeout=support.SHORT_TIMEOUT)
-
-        # Only raise errors in the main thread, just the first one.
-        if errors:
-            raise errors[0]
-
-        self.assertEqual(len(results), N_THREADS)
-        for status, headers in results:
-            self.assertEqual(status, 200)
-            # Server, Date, Content-type, Content-Length, x-test
-            self.assertEqual(len(headers), 5)
-            header_map = {k.lower(): v for k, v in headers}
-            self.assertIn("server", header_map)
-            self.assertIn("date", header_map)
-            self.assertTrue(
-                header_map["content-type"].startswith("text/html")
-            )
-            self.assertGreater(int(header_map["content-length"]), 0)
-            # x-test must appear exactly once, not duplicated
-            x_test_values = [
-                v for k, v in headers if k.lower() == "x-test"
-            ]
-            self.assertEqual(x_test_values, ["test-value"])
-
-
 
 class SocketlessRequestHandler(SimpleHTTPRequestHandler):
     def __init__(self, directory=None):