Fix behavior of the console in response to Ctrl-C

[dmgav]

The proposed changes are fixing the issue with processing SIGINT when Ctrl-C is pressed to interrupt a running cell. The new fixed behavior is consistent with jupyter-qtconsole.

Behavior before the fix

1. Kernel created by the console

$ jupyter-console
Jupyter console 6.6.3

Python 3.10.10 | packaged by conda-forge | (main, Mar 24 2023, 20:08:06) [GCC 11.3.0]
Type 'copyright', 'credits' or 'license' for more information
IPython 8.12.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: import time

In [2]: for n in range(20):
   ...:     time.sleep(1)
   ...: 
^C
KeyboardInterrupt escaped interact()

The task is not stopped, so the next command fails:

In [3]: 2 + 4/home/user/Projects/jupyter_console/jupyter_console/ptshell.py:787: UserWarning: The kernel did not respond to an is_complete_request. Setting `use_kernel_is_complete` to False.
  warn('The kernel did not respond to an is_complete_request. '
In [3]: 2 + 4

Unresponsive until the execution of the original command is complete (20 seconds).

In [3]: 2 + 46
Out[3]: In [3]: 2 + 4
   ...: 

2. Connecting to existing kernel

$ jupyter-console --existing
Jupyter console 6.6.3

Python 3.10.10 | packaged by conda-forge | (main, Mar 24 2023, 20:08:06) [GCC 11.3.0]
Type 'copyright', 'credits' or 'license' for more information
IPython 8.12.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: import time

In [7]: for n in range(20):
   ...:     time.sleep(1)
   ...: 
^C
KeyboardInterrupt escaped interact()

(The kernel keeps executing the cell, the console needs to be restarted to continue normal operation).

Behavior After the Fix

1. Kernel created by the console

$ jupyter-console
Jupyter console 6.6.3

Python 3.10.10 | packaged by conda-forge | (main, Mar 24 2023, 20:08:06) [GCC 11.3.0]
Type 'copyright', 'credits' or 'license' for more information
IPython 8.12.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: import time

In [2]: for n in range(20):
   ...:     time.sleep(1)
   ...: 
^C---------------------------------------------------------------------------
KeyboardInterrupt                         Traceback (most recent call last)
Cell In[2], line 2
      1 for n in range(20):
----> 2     time.sleep(1)

KeyboardInterrupt: 

In [3]: 

( The running cell is immediately stopped and the console is ready for the next command)

3. Connecting to existing kernel (Ctrl-C is ignored, task can not be stopped)

$ jupyter-console --existing
Jupyter console 6.6.3

Python 3.10.10 | packaged by conda-forge | (main, Mar 24 2023, 20:08:06) [GCC 11.3.0]
Type 'copyright', 'credits' or 'license' for more information
IPython 8.12.0 -- An enhanced Interactive Python. Type '?' for help.

IPython profile: collection_sim

In [1]: import time

In [13]: for n in range(20):
    ...:     time.sleep(1)
    ...: 
^CERROR: Cannot interrupt kernels we didn't start.

(The running cell can not be stopped by design, the console displays normal message and continues to work normally after the cell execution is complete)