Deprecated kernel_id param in GatewayKernelClient init() by vincentye38 · Pull Request #1603 · jupyter-server/jupyter_server

vincentye38 · 2026-02-19T19:38:28Z

Deprecated kernel_id parameter as required parameter from GatewayClient ctor because its supper class's ctor doesn't have this parameter. When a kernel manager try to instantiate an object of it, it doesn't know GatewayClient is the concrete class and It need to pass kernel_id to the ctor. Thus, It fails with the following error message. kernel_id is only for constructing ws_url (gateway websocket url.) Replace kernel_id with ws_url property. So the kernel manager can set ws_url instead of kernel id.
The kernel_id parameter caused the following exception when the ctor is called by self.kernel_client = self.client(session=self.session) in KernelManager.init

[W 2026-02-18 18:31:50.832 ServerApp] wrote error: "GatewayKernelClient.__init__() missing 1 required positional argument: 'kernel_id'"
    Traceback (most recent call last):
      File "/Users/xiang_ye/github/aiml-jupyter-server/jupyter_server/services/sessions/handlers.py", line 90, in post
        s_model = await sm.create_session(
                  ^^^^^^^^^^^^^^^^^^^^^^^^
      File "/Users/xiang_ye/.conda/envs/saturn/lib/python3.11/site-packages/jupyter_server_documents/session_manager.py", line 249, in create_session
        session_model = await super().create_session(
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/Users/xiang_ye/github/aiml-jupyter-server/jupyter_server/services/sessions/sessionmanager.py", line 286, in create_session
        kernel_id = await self.start_kernel_for_session(
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/Users/xiang_ye/github/aiml-jupyter-server/jupyter_server/services/sessions/sessionmanager.py", line 359, in start_kernel_for_session
        kernel_id = await self.kernel_manager.start_kernel(
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/Users/xiang_ye/github/aiml-jupyter-server/jupyter_server/services/kernels/kernelmanager.py", line 233, in _async_start_kernel
        kernel_id = await self.pinned_superclass._async_start_kernel(self, **kwargs)
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/Users/xiang_ye/.conda/envs/saturn/lib/python3.11/site-packages/jupyter_client/multikernelmanager.py", line 263, in _async_start_kernel
        km, kernel_name, kernel_id = self.pre_start_kernel(kernel_name, kwargs)
                                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/Users/xiang_ye/.conda/envs/saturn/lib/python3.11/site-packages/jupyter_client/multikernelmanager.py", line 209, in pre_start_kernel
        km = self.kernel_manager_factory(
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/Users/xiang_ye/.conda/envs/saturn/lib/python3.11/site-packages/jupyter_client/multikernelmanager.py", line 87, in create_kernel_manager
        km = kernel_manager_ctor(*args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/Users/xiang_ye/.conda/envs/saturn/lib/python3.11/site-packages/nextgen_kernels_api/services/kernels/kernelmanager.py", line 47, in __init__
        self.kernel_client = self.client(session=self.session)
                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/Users/xiang_ye/.conda/envs/saturn/lib/python3.11/site-packages/jupyter_client/manager.py", line 740, in client
        return super().client(**kwargs)  # type:ignore[return-value]
               ^^^^^^^^^^^^^^^^^^^^^^^^
      File "/Users/xiang_ye/.conda/envs/saturn/lib/python3.11/site-packages/jupyter_client/manager.py", line 277, in client
        return self.client_factory(**kw)
               ^^^^^^^^^^^^^^^^^^^^^^^^^
      File "/Users/xiang_ye/.conda/envs/saturn/lib/python3.11/site-packages/jupyter_server_documents/kernel_client.py", line 46, in __init__
        super().__init__(*args, **kwargs)
      File "/Users/xiang_ye/.conda/envs/saturn/lib/python3.11/site-packages/nextgen_kernels_api/services/kernels/client.py", line 87, in __init__
        super().__init__(*args, **kwargs)
    TypeError: GatewayKernelClient.__init__() missing 1 required positional argument: 'kernel_id'

Append session_id to the ws_url so the gateway can replay buffered message during the disconnection. The gateway gate the replay messages by session_id.

vincentye38 · 2026-02-19T20:08:52Z

-            GatewayClient.instance().kernels_endpoint,
-            url_escape(self.kernel_id),
-            "channels",
-        )


Note: I proposed to move ws_url initialization to kernel manager, and make ws_url as a property of kernel client. Because kernel manager is responsible to start kernel process, instantiate a kernel client to connect o the process. So it knows information of how to connect to the kernel process.
Kernel manager will set ws_url of kernel client after it creates the kernel client.

It will be on line 726 instead.

Zsailer

Thanks for the contribution @vincentye38 ! The reconnect logic is a nice addition. A few things to address before this can merge:

Breaking API change — Removing kernel_id from GatewayKernelClient.__init__() will break downstream consumers. Please keep it as an optional kwarg with a deprecation warning and
auto-build ws_url from it for backwards compat.
asyncio.run() in _should_reconnect — This will fail inside a running event loop. Needs to be reworked.

…the creator.

add session_id to gateway url

throw dedicated exception

removed GatewayResponseRouterFinished

vincentye38 · 2026-05-13T19:58:58Z

@lresende @kevin-bates Any comment and concern for PR?

vincentye38 · 2026-05-13T21:05:40Z

I am resolving the failed check.

All unit test passed.

krassowski · 2026-06-03T16:15:45Z

It looks like there are some conflicts which need to be resolved.

krassowski · 2026-06-03T16:22:13Z

+    @property
+    def session_id(self):
+        """The session id."""
+        return self.session.session


Is the definition of a property necessary? Is that to allow customizing it downstream in subclasses or just for convenience? If the latter, should it be private (prefixed with _)?

Subclass can override this property to adapt to what the gateway side uses to key the buffered messages. Currently, Kernel Gateway use session id in the message as key, which is corresponding to self.session.session.

ojarjur · 2026-06-03T16:28:11Z

        self.response_router: Optional[Thread] = None
        self._channels_stopped = False
        self._channel_queues = {}
+        if kernel_id is not None:


The GatewayKernelManager class is still setting this keyword parameter inside of the client method (line 424 in the LHS of the diff).

If it is being deprecated, then we should also update the existing caller in this file to use the new ws_url traitlet instead.

@vincentye38 I suppose the comment above still needs addressing?

fixed in a new commit for GatewayKernelManager in line #425

Co-authored-by: Michał Krassowski <5832902+krassowski@users.noreply.github.com>

…ient Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

vincentye38 commented Feb 19, 2026

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Comment thread jupyter_server/gateway/managers.py

vincentye38 commented Feb 19, 2026

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Zsailer reviewed Apr 2, 2026

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Comment thread jupyter_server/gateway/managers.py Outdated

Comment thread jupyter_server/gateway/managers.py Outdated

Comment thread jupyter_server/services/kernels/websocket.py Outdated

Zsailer added the enhancement label Apr 13, 2026

Carreau added this to the Future milestone May 1, 2026

Zsailer requested review from kevin-bates and lresende May 12, 2026 16:06

Vincent Ye added 7 commits May 13, 2026 12:55

remove kernel_id para from ctor. extracted gateway url generation to …

b515f62

…the creator.

reconnect to gateway

d1488c6

add session_id to gateway url

handle kernel_id param

69f29c9

fix test error

8046d57

throw dedicated exception

fix DeprecationWarning error in pytest

e230469

removed limit for reconnection atempt

987fdbb

removed GatewayResponseRouterFinished

fixed gateway kernel client capping throughput at 1 msg/sec.

50bf889

vincentye38 force-pushed the main-apple-oss branch from 8731408 to 50bf889 Compare May 13, 2026 19:55

Vincent Ye added 3 commits May 13, 2026 14:31

Reverted to Empty from TimeoutException

1168aac

Add configuration to enable reconnect.

5baa3fd

triggerd PR check

80beac4

vincentye38 commented May 14, 2026

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Comment thread jupyter_server/services/sessions/handlers.py Outdated

removed debug log

cbbdd78

vincentye38 force-pushed the main-apple-oss branch from a0f88dc to 5faaca4 Compare May 15, 2026 03:46

reverted reconnection

607cc2a

vincentye38 force-pushed the main-apple-oss branch from 5faaca4 to 607cc2a Compare May 15, 2026 03:52

update session_id param name

8fce41e

vincentye38 changed the title ~~Enhance GatewayClient~~ Deprecated kernel_id param in GatewayClient init() May 20, 2026

vincentye38 changed the title ~~Deprecated kernel_id param in GatewayClient init()~~ Deprecated kernel_id param in GatewayKernelClient init() May 20, 2026

krassowski reviewed Jun 3, 2026

View reviewed changes

vincentye38 and others added 2 commits June 3, 2026 09:26

Merge branch 'main' into main-apple-oss

f990cae

core: pre-commit fixes

0749fb6

ojarjur reviewed Jun 3, 2026

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vincentye38 and others added 2 commits June 3, 2026 09:35

Apply suggestions from code review

c2a8934

Co-authored-by: Michał Krassowski <5832902+krassowski@users.noreply.github.com>

Use ws_url instead of deprecated kernel_id in GatewayKernelManager.cl…

84a7fce

…ient Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Zsailer reviewed Jun 18, 2026

View reviewed changes

Comment thread jupyter_server/gateway/managers.py Outdated

fix import position

b9eee25

krassowski mentioned this pull request Aug 13, 2026

Weekly Team Meetings: Jan–Dec 2026 jupyterlab/frontends-team-compass#301

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