python - Jupyter magic to handle notebook exceptions

Question

I have a few long-running experiments in my Jupyter Notebooks. Because I don't know when they will finish, I add an email function to the last cell of the notebook, so I automatically get an email, when the notebook is done.

But when there is a random exception in one of the cells, the whole notebook stops executing and I never get any email. So I'm wondering if there is some magic function that could execute a function in case of an exception / kernel stop.

Like

def handle_exception(stacktrace):
    send_mail_to_myself(stacktrace)


%%in_case_of_notebook_exception handle_exception # <--- this is what I'm looking for

The other option would be to encapsulate every cell in try-catch, right? But that's soooo tedious.

Thanks in advance for any suggestions.

Answer 1

Such a magic command does not exist, but you can write it yourself.

from IPython.core.magic import register_cell_magic

@register_cell_magic('handle')
def handle(line, cell):
    try:
        exec(cell)
    except Exception as e:
        send_mail_to_myself(e)
        raise # if you want the full trace-back in the notebook

It is not possible to load the magic command for the entire notebook automatically, you have to add it at each cell where you need this feature.

%%handle

some_code()
raise ValueError('this exception will be caught by the magic command')