Re: [BUG] FAILED test-ob-python/session-multiline

[Jack Kamm]

Ihor Radchenko <yantar92@posteo.net> writes:

> Jack Kamm <jackkamm@gmail.com> writes:
>
>>>    FAILED   376/1256  test-ob-python/session-multiline (0.011955 sec) at 
>>> ../lisp/test-ob-python.el:105
>>
>> Hmmm. Do you have an idea of how long this has been happening, and how
>> frequently it breaks?
>
> For months.
>
>> My first suspicion is the large ob-python commit I pushed on Tuesday:
>>
>> https://git.savannah.gnu.org/cgit/emacs/org-mode.git/commit/?id=579e8c572345c42ad581d3ddf0f484567d55a787
>
> So, should not be the recent commit.

This one might take some time to fix, since it's hard to reproduce and
I'm not sure the cause of it. But here are 3 different solutions I am
considering now:

1. In addition to printing `org-babel-python-eoe-indicator' after
   execution, we could also print out a "beginning of execution"
   indicator before execution, and then capture the output between the
   beginning and end indicators. This is how the async session
   execution works, and should avoid any possibility of capturing
   prompts.

2. Instead of relying on our own custom `org-babel-python-send-string',
   we could try switching to python.el's
   `python-shell-send-string-no-output', which is probably more
   robust. This would also allow removing the ugly
   `org-babel-python-eoe-indicator' we currently print.

   Downside is that the output would not be echoed into the session
   anymore. To fix that, we could manually insert the captured output
   into the comint session buffer after execution.  Alternatively, we
   could add an argument to `python-shell-send-string-no-output' to
   avoid suppressing output, submit it upstream to python.el, and then
   backport to Org to support older emacs versions.

3. Revisit a series of commits I made in 2020, which was supposed to
   make session evaluation more robust, and was inspired by
   `python-shell-send-string-no-output':
   https://git.sr.ht/~bzg/org-mode/commit/4df12ea39

   However, I had to partially revert that work, due to compatibility
   issue with emacs 26.3:
   https://list.orgmode.org/871rjcan53.fsf@kyleam.com/

   I think we no longer support emacs 26.3, so I could potentially
   revisit this now -- but it's been a few years and will take some
   time to refresh my memory about this.

Of these options, Option 1 is the easiest, and the most certain to solve
this bug. Options 2 and 3 are more difficult and riskier, but would have
other benefits if they work: we can remove the ugly
`org-babel-python-eoe-indicator' that is currently printed to the
session, and/or reduce long-term maintenance burden by relying on
python.el's implementation for capturing output.