Fix to remove potential memory leak on Jupyter Notebooks ZMQChannelHandler code

[Vishwajeet0510]

Adding a session to the _open_sessions list only after validating kernel. This will prevent memory wastage if any requests are made with an incorrect kernel ID.

[kevin-bates]

Thanks @Vishwajeet0510 and @rahul26goyal!

[Vishwajeet0510]

Hey @kevin-bates

Do you have any idea when this change will be released?

[kevin-bates]

Sorry for the delay @Vishwajeet0510! I'll try to cut a 6.4.8 release soon (within the next day or two).

[kevin-bates]

FYI - Notebook 6.4.8 is available on pypi: https://pypi.org/project/notebook/6.4.8/. Thanks for your help @Vishwajeet0510 and @rahul26goyal.

[blink1073]

I added this to jupyter-server/jupyter_server#110, if you'd like to make the same submission in the new Jupyter Server @Vishwajeet0510

[kevin-bates]

Ah, yes, thank you Steve!

@Vishwajeet0510 - since EG uses JupyterServer in more recent releases, a similar change would be advised. Thank you!

[Vishwajeet0510]

Hello @kevin-bates and @blink1073

Thanks for the quick followup and release. I will create a similar PR for jupyter_server as well.

[rahul26goyal]

thanks a lot @kevin-bates for all the help in resolving this issue. :)

[Vishwajeet0510]

Hello @kevin-bates

Is it possible to back port this fix so it is available with Notebook v6.0.3? We are currently using JEG v2.1.0 and it is not compatible with Jupyter Notebook version >6.0.3. Please let us know if this would be possible.

[kevin-bates]

Hi @Vishwajeet0510 - could you please elaborate on why EG 2.1.0 is incompatible with NB >6.0.3? The only compatibility issue I'm aware of is jupyter_client > 7 and EG has caps in place (in its more recent releases) to address that.

[Vishwajeet0510]

Hi @kevin-bates

As per my understanding, from Jupyter Notebook v6.1.0 async kernel management is supported and corresponding changes on JEG side are supported from JEG v2.1.1 onwards.

[kevin-bates]

Hi @Vishwajeet0510 - since this is EG-specific and I'd like to explore things (possibly creating a longer comment chain), I've opened this discussion item in EG and hoping you and @rahul26goyal can join me there: jupyter-server/enterprise_gateway#1037

We can update this thread once things are resolved. Thank you.