Notebook: Can a Jupyter notebook programmatically halt itself?

[jeremydouglass]

Can a Jupyter notebook programmatically halt itself, such that the notebook no longer appears in the "Running" tab?

At the end of a notebook "Run All", I would like the last notebook cell to contain code, and for that code to trigger the equivalent of:

• the "Running tab > Shutdown notebook" action
• ...or, failing that, the "Close and Halt" menu item

Can this be done with javascript, or with %magic, or something else?

I am running the latest Docker image Jupyer Datascience Notebook, not JupyterHub.

---

forum cross-posted

[takluyver]

(Responded on the mailing list)

[jeremydouglass]

Yes, a Jupyter notebook can programmatically halt itself.

Use a cell at the end of an iPython notebook like this:

%%javascript
Jupyter.notebook.session.delete();

• On "Run All" the final %%javascript cell "Jupyter.notebook.session.delete();" correctly stops the notebook.
• The notebook interface shows "No Kernel", the Running tab no longer lists the notebook.
• The previous cell incorrectly still shows a running status [ * ], however the output from that cell has already returned. This can be misleading, but seems minor -- I can report it as a separately issue if anyone cares.

Restart the stopped notebook with:

• Menu > Kernel > Restart ... "Dead Kernel" warning > Try restarting now
• ...or refresh the browser tab.

A demo ipynb file is posted on the forum thread

[takluyver]

This led to a question: should it be possible to use exit() to stop the kernel in a notebook? At present, using exit() will make the notebook think that the kernel has died, and it will automatically start a new kernel. I think that exit() should probably put the notebook interface into the state it arrives in if it gives up on trying to start a kernel.

[jeremydouglass]

As a current workaround for those interested in notebook halting, I developed this %%javascript cell for use at the end of a Run All sequence. It uses a modal dialog to halt the notebook kernal (and optionally restart it on user click).

---

Notebook Halt / Restart cell

_When included at the bottom of a notebook, it will stop the notebook at the end of Run All, and pop up a modal dialog letting the user know that the notebook was auto-stopped at the end of the run. The dialog offers a "Kernel Restart" button which restarts the notebook._

%%javascript
require(
    ["base/js/dialog"], 
    function(dialog) {
        dialog.modal({

                title: 'Notebook Halted',
                body: 'This notebook is no longer running; the kernel has been halted. Close the browser tab, or, to continue working, restart the kernel.',
                buttons: {
                    'Kernel restart': { click: function(){ Jupyter.notebook.session.restart(); } }
                }
        });
    }
);
Jupyter.notebook.session.delete();

https://groups.google.com/forum/#!topic/jupyter/3zAVHofQykg

[ivanov]

Related to this, in #2070, which was recently merged, I added a "Shutdown" menu item to the Kernel menu.

[ivanov]

Hey there, I'm going through old issues and it seems to me that it makes sense to close this one.

@jeremydouglass figured out a workaround in the forum link posted two comments above this one, and I added "Shutdown" item to the Kernel menu.

Thanks everyone and happy hacking! :bowtie:

[saharmilis]

u can use for a specific cell
assert False