add docs

docs/migration.md

@@ -1,5 +1,41 @@
 # Migration Guide
 
+## Jupyter Client 8.0 to 9.0
+
+Overall changes: removed direct usages of `tornado` in favor of `asyncio` loops.
+We are still using `zmq.eventloop.zmqstream.ZMQStream`, which uses `tornado`
+loops internally.
+
+### API Changes
+
+The following `loop` properties are now asyncio loops:
+
+- `jupyter_client.ioloop.manager.IOLoopKernelManager.loop`
+- `jupyter_client.ioloop.manager.AsyncIOLoopKernelManager.loop`
+- `jupyter_client.ioloop.restarter.IOLoopKernelRestarter.loop`
+- `jupyter_client.ioloop.restarter.AsyncIOLoopKernelRestarter.loop`
+- `jupyter_client.threaded.ThreadedZMQSocketChannel.loop`
+- `jupyter_client.threaded.IOLoopThread.ioloop`
+- `jupyter_client.threaded.ThreadedKernelClient.ioloop`
+
+The `jupyter_client.kernelapp.KernelApp` class now subclasses
+`jupyter_core.application.JupyterAsyncApp`, and  performs its initialization
+from within an asyncio loop.
+
+The following function was added as a shim to the `jupyter_core` utility:
+
+- `jupyter_client.utils.ensure_event_loop`
+
+## Jupyter Client 7.0 to 8.0
+
+The main goal of this release was to improve handling of asyncio and remove
+the need for `nest_asyncio`.
+
+### API Changes
+
+- `jupyter_client.asynchronous.client.AsyncKernelClient.context` is now a `zmq.asyncio.Context`
+- `jupyter_client.asynchronous.client.AsyncKernelClient.*_channel_class` are now instances of `jupyter_client.channels.AsyncZMQSocketChannel`
+
 ## Jupyter Client 6.0 to 7.0
 
 ### API Changes

jupyter_client/ioloop/restarter.py

@@ -10,7 +10,8 @@
 import asyncio
 import time
 
-from jupyter_core.utils import ensure_async
+from jupyter_core.utils import ensure_async, ensure_event_loop
+from traitlets import Instance
 
 from ..restarter import KernelRestarter
 
@@ -21,6 +22,11 @@ class IOLoopKernelRestarter(KernelRestarter):
     _poll_task: asyncio.Task | None = None
     _running = False
 
+    loop = Instance(asyncio.AbstractEventLoop)  # type:ignore[type-abstract]
+
+    def _loop_default(self) -> asyncio.AbstractEventLoop:
+        return ensure_event_loop()
+
     def start(self) -> None:
         """Start the polling of the kernel."""
         if not self._poll_task:

jupyter_client/threaded.py

@@ -86,6 +86,10 @@ def close(self) -> None:
                 msg = f"Error closing socket {self.socket}: {e}"
                 log.warning(msg, RuntimeWarning, stacklevel=2)
 
+    def flush(self):
+        """Flush the channel."""
+        pass
+
     def _thread_close(self) -> None:
         if self.socket is None:
             return

tests/test_multikernelmanager.py

@@ -602,6 +602,7 @@ async def test_bad_kernelspec_pending(self):
         await ensure_future(km.shutdown_kernel(kernel_id))
         assert kernel_id not in km.list_kernel_ids()
 
+    @skip_win32
     async def test_stream_on_recv(self):
         mkm = self._get_tcp_km()
         kid = await mkm.start_kernel(stdout=PIPE, stderr=PIPE)