How can I build jupyterlab faster and reduce vendors~main.js?

I tried expanding RAM space and it finally built successfully. So perhaps it is because of RAM space.

Every time I run jupyter lab build it takes hours to build and when it is built, it takes 3-5min for chrome to load jupyter lab pages.
I analyzed the pages and found out a vendors~main*******.js file is as big as 32.3 MB which I think is created by webpack.
I went to github issues and tried as what is mentioned. The problem is still there.
So I wonder how to make jupyterlab build faster and create vendors~main.js with smaller size.
Thanks for your help if any:).

It should not be taking literal hours, can you tell us more about your setup? Are you running dev builds (the default) or prod builds?

In our setup on a EC2 t2.small server, JupyterLab is able to build with 4 extensions (one of them quite meaty) in ~1.5min.

One thing that might be impacting you is #6804, which is fixed on master but not yet released. Try the workaround I describe there and see if it helps.

1 Like

Thanks for your reply. Here’s how I install jupyterlab and hope it helps to locate the problem.

  1. pip install jupyterlab and pip install jupyter
  2. wget {url for latest npm} and setup ln -s for npm and node, the version ofr node is 12.x
  3. jupyter lab install(failed)
  4. I looked into error log. It said I don’t have python2 since I am running on Ubuntu 18.04. So I run apt install python
  5. jupyter lab install took more than 2hours to finish so I rebooted my computer and changed webpack --config to webpack in package.json. It still took long time to build but finally succeeded.
  6. jupyter lab and open chrome, the vendors~main.js shows up as big as 32MB.

I will try what you said in #6804 and will tell you whether it works.
Thanks again for your reply and help.

You could also try the fix at - use --dev-build=False when installing something

I tried jupyter lab build --dev-build=False and my computer is still running ( more than one hour) so it seems dev-build=False doesn’t work. Do you mean jupyter lab build --dev-build=False or jupyter labextension install XXXX --dev-build=False?

Can you try the new alpha on pypi, 1.1.0a1 ? It has some fixes merged to build smaller builds by default.

pip install --pre --upgrade jupyterlab

FYI, here’s log content after trying jupyter lab build --dev-build=False and source-map but failed.

  1 [LabBuildApp] Building in /usr/local/share/jupyter/lab
  2 [LabBuildApp] Node v12.7.0
  4 [LabBuildApp] Building jupyterlab assets
  5 [LabBuildApp] > node /usr/local/lib/python3.6/dist-packages/jupyterlab/staging/yarn.js install --non-interactive
  6 [LabBuildApp] yarn install v1.15.2
  7 [1/5] Validating package.json...
  8 [2/5] Resolving packages...
  9 success Already up-to-date.
 10 Done in 0.89s.
 12 [LabBuildApp] > node /usr/local/lib/python3.6/dist-packages/jupyterlab/staging/yarn.js yarn-deduplicate -s fewer --fail
 13 [LabBuildApp] yarn run v1.15.2
 14 $ /usr/local/share/jupyter/lab/staging/node_modules/.bin/yarn-deduplicate -s fewer --fail
 15 Done in 0.41s.
 17 [LabBuildApp] > node /usr/local/lib/python3.6/dist-packages/jupyterlab/staging/yarn.js run build:prod
 18 [LabBuildApp] yarn run v1.15.2
 19 $ cross-env NODE_OPTIONS=--max_old_space_size=4096 webpack --config
 20 error Command failed with exit code 1.
 21 info Visit for documentation about this command.
 22                                                                                                                                                           23 [LabBuildApp] JupyterLab failed to build
 24 [LabBuildApp] Traceback (most recent call last):                                                                                                          25
 26 [LabBuildApp]   File "/usr/local/lib/python3.6/dist-packages/jupyterlab/", line 47, in debug_logging                                           27     yield                                                                                                                                                 28
 29 [LabBuildApp]   File "/usr/local/lib/python3.6/dist-packages/jupyterlab/", line 80, in start                                                     30     command=command, logger=self.log)
 31                                                                                                                                                           32 [LabBuildApp]   File "/usr/local/lib/python3.6/dist-packages/jupyterlab/", line 373, in build
 33     command=command, clean_staging=clean_staging)                                                                                                         34                                                                                                                                                           35 [LabBuildApp]   File "/usr/local/lib/python3.6/dist-packages/jupyterlab/", line 566, in build
 36     raise RuntimeError(msg)                                                                                                                               37
 38 [LabBuildApp] RuntimeError: JupyterLab failed to build
 40 [LabBuildApp] Exiting application: JupyterLab 

I tried to update jupyterlab it doesn’t work:joy:
I looked into log file. It should be a webpack problem. Perhaps the config file coursed the problem.

  1 var merge = require('webpack-merge');
  2 var config = require('./webpack.config');
  4 config[0] = merge(config[0], {
  5   mode: 'production',
  6   devtool: 'source-map',
  7   optimization: {
  8     minimize: false
  9   }
 10 });
 12 module.exports = config;