From 175b5482e7570680dd8afc04f108c376bece7133 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 2 Jun 2026 03:04:19 +0000
Subject: [PATCH 1/2] Initial plan


From 3174ece65bdadf57fba0e524dc0a095e801510b2 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 2 Jun 2026 03:08:07 +0000
Subject: [PATCH 2/2] Avoid deprecated Tornado IOLoop APIs in WebApp

---
 cortex/tests/test_webgl_serve.py | 31 +++++++++++++++++++++++++++++++
 cortex/webgl/serve.py            |  6 +-----
 2 files changed, 32 insertions(+), 5 deletions(-)
 create mode 100644 cortex/tests/test_webgl_serve.py

diff --git a/cortex/tests/test_webgl_serve.py b/cortex/tests/test_webgl_serve.py
new file mode 100644
index 000000000..440e8d467
--- /dev/null
+++ b/cortex/tests/test_webgl_serve.py
@@ -0,0 +1,31 @@
+import cortex.webgl.serve as serve
+
+
+def test_webapp_run_uses_current_ioloop(monkeypatch):
+    class FakeIOLoop:
+        def __init__(self):
+            self.started = False
+
+        def start(self):
+            self.started = True
+
+    class FakeHTTPServer:
+        def __init__(self, application, io_loop=None):
+            self.application = application
+            self.io_loop = io_loop
+            self.listen_port = None
+
+        def listen(self, port):
+            self.listen_port = port
+
+    fake_ioloop = FakeIOLoop()
+
+    monkeypatch.setattr(serve.tornado.ioloop.IOLoop, "current", lambda: fake_ioloop)
+    monkeypatch.setattr(serve.tornado.httpserver, "HTTPServer", FakeHTTPServer)
+
+    app = serve.WebApp([], 0)
+    app.run()
+
+    assert app.ioloop is fake_ioloop
+    assert fake_ioloop.started
+    assert app.server.listen_port == 0
diff --git a/cortex/webgl/serve.py b/cortex/webgl/serve.py
index 354c665d0..3bfb08222 100644
--- a/cortex/webgl/serve.py
+++ b/cortex/webgl/serve.py
@@ -321,11 +321,7 @@ def n_clients(self) -> int:
         return num
 
     def run(self):
-        ioloop: tornado.ioloop.IOLoop = (
-            tornado.ioloop.IOLoop()
-        )  # why is annotation necessary?
-        ioloop.clear_current()
-        ioloop.make_current()
+        ioloop: tornado.ioloop.IOLoop = tornado.ioloop.IOLoop.current()
         self.ioloop = ioloop
         application = tornado.web.Application(self.handlers, gzip=True)
         # If tornado version is 5.0 or greater, io_loop arg does not exist