Notebooks: backspaces are rendered as printable rather than control characters in output cells

[bvenreply]

Bug Description:

Backspaces are rendered as printable rather than control characters in notebook output cells.

Here's an example, from the Keras curses-like model training progress reporting interface:

Steps to Reproduce:

• Create a Jupyter notebook in Theia, and run this python code within a cell:

  import time
  
  msg = "abcdef"
  
  for i in range(5):
      print(msg, end="")
      time.sleep(1)
      for j in msg:
          print("\b", end="", flush=True)
      time.sleep(0.5)

Here's a comparison with the same code run in vscode, which displays the expected output:

Additional Information

• Operating System: 5.10.192-183.736.amzn2.x86_64 GNU/Linux on the server 6.1.0-13-amd64 GNU/Linux on the client
• Theia Version: 1.43.1
• Browser: Chromium version 119.0.6045.105
• Python jupyter kernel: tested with 3.8, 3.11 and 3.12

This is a less trivial issue than it may appear: taking the above example of Keras model training, note that many thousands of these lines are printed throughout the model training and the cell attempts to render them all, to the point that the browser is slowed down and the notebook becomes unusable.

[JonasHelming]

@msujew Marc, are you aware of this BR? Is this maybe something you want to adress as part of #13012 ?

[msujew]

@JonasHelming Seems to me like this should be treated as a separate thing to #13012.

@jonah-iden Can you take a look at this? I'm wondering whether vscode is doing preprocessing here, or whether the webview is doing something special that we don't support.

[jonah-iden]

sure i can take a look sometime this week

[kkistm]

Just curious if there are any updates about the ticket.

[jonah-iden]

I think i found the Solution and am currently testing it