What Do I Do If There Is a Noticeable Delay on the First Code Cell Execution After Opening an .ipynb File in Code Server?

Symptom

There is a noticeable delay (over 30 seconds) when the code cell is executed for the first time after an .ipynb file is opened in Code Server.

Figure 1 Opening an .ipynb file

Possible Causes

There is no ipykernel dependency package in the current image environment. The first time you run a notebook file, Code Server automatically starts the backend installation. Since dependencies must be downloaded and compiled from the official source, this initialization process can take quite a while.

Solution

You are advised to manually install ipykernel.

1. In the navigation pane of Code Server, click and choose Terminal > New Terminal.
2. Install ipykernel.

   # (Optional) Check the current Conda environment.
   conda env list
   
   # Activate the base environment. (If you are using a different environment, replace base with the name of that environment.)
   conda activate base
   
   # Install ipykernel. (You are advised to use a mirror source in China to speed up the download.)
   pip install ipykernel

   Figure 2 Installing ipykernel
   
3. Run the following command to check whether ipykernel is installed successfully:

   pip show ipykernel

   If the ipykernel version information is displayed, ipykernel is successfully installed.

   Figure 3 Viewing ipykernel details