From 4fe6313058942735f309f7df31034a3030070698 Mon Sep 17 00:00:00 2001
From: Min RK <benjaminrk@gmail.com>
Date: Mon, 31 Jul 2023 10:02:04 +0200
Subject: [PATCH 1/3] avoid starting IOPub background thread after it's been
 stopped

loop.add_callback(loop.stop) called before the thread starts
can get consumed by the run_sync before loop.start,
so it won't close the loop.
---
 ipykernel/iostream.py | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/ipykernel/iostream.py b/ipykernel/iostream.py
index 5c2818dcc..9aafa66ad 100644
--- a/ipykernel/iostream.py
+++ b/ipykernel/iostream.py
@@ -57,6 +57,7 @@ def __init__(self, socket, pipe=False):
             piped from subprocesses.
         """
         self.socket = socket
+        self._stopped = False
         self.background_socket = BackgroundSocket(self)
         self._master_pid = os.getpid()
         self._pipe_flag = pipe
@@ -83,7 +84,12 @@ def _start_event_gc():
             self._event_pipe_gc_task = asyncio.ensure_future(self._run_event_pipe_gc())
 
         self.io_loop.run_sync(_start_event_gc)
-        self.io_loop.start()
+
+        if not self._stopped:
+            # avoid race if stop called before start thread gets here
+            # probably only comes up in tests
+            self.io_loop.start()
+
         if self._event_pipe_gc_task is not None:
             # cancel gc task to avoid pending task warnings
             async def _cancel():
@@ -219,10 +225,16 @@ def start(self):
 
     def stop(self):
         """Stop the IOPub thread"""
+        self._stopped = True
         if not self.thread.is_alive():
             return
         self.io_loop.add_callback(self.io_loop.stop)
-        self.thread.join()
+
+        self.thread.join(timeout=30)
+        if self.thread.is_alive():
+            # avoid infinite hang if stop fails
+            msg = "IOPub thread did not terminate in 30 seconds"
+            raise TimeoutError(msg)
         # close *all* event pipes, created in any thread
         # event pipes can only be used from other threads while self.thread.is_alive()
         # so after thread.join, this should be safe

From 7d49b0f8a8f9dc3c04a0906fde2fbb6e15f7bde8 Mon Sep 17 00:00:00 2001
From: Steven Silvester <steven.silvester@ieee.org>
Date: Sat, 2 Sep 2023 14:57:31 -0500
Subject: [PATCH 2/3] handle timeout on cancel operation

---
 ipykernel/iostream.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/ipykernel/iostream.py b/ipykernel/iostream.py
index 9aafa66ad..cb7685440 100644
--- a/ipykernel/iostream.py
+++ b/ipykernel/iostream.py
@@ -94,8 +94,11 @@ def _start_event_gc():
             # cancel gc task to avoid pending task warnings
             async def _cancel():
                 self._event_pipe_gc_task.cancel()  # type:ignore
-
-            self.io_loop.run_sync(_cancel)
+            
+            try:
+                self.io_loop.run_sync(_cancel)
+            except TimeoutError:
+                pass
         self.io_loop.close(all_fds=True)
 
     def _setup_event_pipe(self):

From b0d05c81519b02444667b39aa3ef9d3b59abb6b4 Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Sat, 2 Sep 2023 19:57:41 +0000
Subject: [PATCH 3/3] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 ipykernel/iostream.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ipykernel/iostream.py b/ipykernel/iostream.py
index cb7685440..74e65e4d9 100644
--- a/ipykernel/iostream.py
+++ b/ipykernel/iostream.py
@@ -94,7 +94,7 @@ def _start_event_gc():
             # cancel gc task to avoid pending task warnings
             async def _cancel():
                 self._event_pipe_gc_task.cancel()  # type:ignore
-            
+
             try:
                 self.io_loop.run_sync(_cancel)
             except TimeoutError: