Extremely slow kernel starts

[Tom Baldwin]

Hello group, I'm stuck tracking down a problem in both of my Jupyter installations and I'd love to hear some ideas of things to try.

I am experiencing very slow kernel starts in the Jupyter notebook. Sometimes kernels are ready right away after creating/opening a notebook, but more commonly I need to wait a minute or more before I can execute cells.

This is using Jupyter 4.1.0, Python 3.4, and Chrome. I've attached the text from Chrome's js console and the terminal output (from ``jupyter notebook --debug``).

When I e.g. open a new notebook, the circle in the upper right is closed in and syntax highlighting does not work. The last message in the terminal is

    [D 16:40:24.305 NotebookApp] 304 GET /nbextensions/widgets/notebook/js/extension.js (::1) 0.88ms

While the JS console has a warning

    actions jupyter-notebook:find-and-replace does not exist, still binding it in case it will be defined later...

If I attempt to execute cells during this time, the JS console displays the message

    main.min.js:21623 Can't execute, kernel is not connected.

Occasionally, there will also be a message in the JS console

    main.min.js:33736 ipywidgets package not installed.  Widgets are not available.

but not always.

Eventually (after more than a minute), the kernel connects, according to the JS console. I still cannot execute cells, but they fail in a different way. If I try to execute a cell, an asterisk is produced in the brackets instead of a message in the JS console.

During this second period of waiting, the terminal sporadically reports progress, but has some timeout messages such as

    [W 16:41:49.714 NotebookApp] Timeout waiting for kernel_info reply from 2b8be6e3-f5c7-4ee5-b38b-48cdab20617a

After another minute or so of waiting, this second period of waiting comes to a close with the terminal message

    [D 16:42:56.981 NotebookApp] Received kernel info: {'implementation': 'ipython', 'implementation_version': '4.1.2', ...

Which I've truncated for clarity. The kernel_ready message appears in the JS console, and I can use the notebook as normal after that with no delays (until I restart the kernel and the same thing happens).

Based on some searching I thought that it might be due to a rogue notebook extension. I tried disabling them all (by deleting the nbextensions folders in each of the data paths given by ``jupyter --paths``) but this solves no problems.

I'd love to hear any ideas on what to check next in order to track down the source of this problem. Thanks in advance for your thoughts.

[MinRK]

The fact that it takes so long for the kernel_info_reply to arrive suggests that something is actually taking a long time to load in starting up the kernel. Taking more than a few seconds is quite unusual for IPython. How long does it take you to start terminal IPython? Do you have any startup files or `exec_lines` in your IPython configuration?

-MinRK

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[Tom Baldwin]

Thanks for your reply, Min. Terminal IPython starts right away, taking about a second. My ``profile_default`` folder contains no ``.py`` files at any level, so there are neither startup nor config files as far as I know.

tk

On Monday, March 14, 2016 at 5:06:38 AM UTC-7, Min RK wrote:

The fact that it takes so long for the kernel_info_reply to arrive suggests that something is actually taking a long time to load in starting up the kernel. aking more than a few seconds is quite unusual for IPython. How long does it take you to start terminal IPython? Do you have any startup files or `exec_lines` in your IPython configuration?

-MinRK

[Greg Yang]

Long restarts happen to me as well over different machines. It's quite annoying.

[chriddy]

Same issue here on Windows 7. Console output is attached. Note how each of these connection attemps to localhost takes 3 secs:

[D 14:39:15.003 NotebookApp] Connecting to: tcp://127.0.0.1:53196
[D 14:39:18.008 NotebookApp] Connecting to: tcp://127.0.0.1:53197
[D 14:39:21.010 NotebookApp] Connecting to: tcp://127.0.0.1:53198

Might this in fact be a networking issue?