In case you're developing the plugin in C and not LUA, behind the scenes the
LUA mechanism is concatenating all log_user() strings into a single variable
(user_msg). When the LUA code completes, the C code sets the *err_msg argument
to the job_submit()/job_modify() function to that string, then NULLs-out
user-msg. (There's a mutex around all of that code so slurmctld never executes
LUA job submit/modify scripts concurrently.) The slurmctld then communicates
that returned string back to sbatch/salloc/srun for display to the user.
Your C plugin would do likewise — set *err_msg before returning from
job_submit()/job_modify() — and needn't be mutex'ed if the code is reentrant.
> On Jul 19, 2023, at 08:37, Angel de Vicente <angel.de.vice...@iac.es> wrote:
>
> Hello Lorenzo,
>
> Lorenzo Bosio <lorenzo.bo...@unito.it> writes:
>
>> I'm developing a job submit plugin to check if some conditions are met
>> before a job runs.
>> I'd need a way to notify the user about the plugin actions (i.e. why its
>> jobs was killed and what to do), but after a lot of research I could only
>> write to logs and not the user shell.
>> The user gets the output of slurm_kill_job but I can't find a way to add a
>> custom note.
>>
>> Can anyone point me to the right api/function in the code?
>
> In our "job_submit.lua" script we have the following for that purpose:
>
> ,----
> | slurm.log_user("%s: WARNING: [...]", log_prefix)
> `----
>
> --
> Ángel de Vicente
> Research Software Engineer (Supercomputing and BigData)
> Tel.: +34 922-605-747
> Web.: http://research.iac.es/proyecto/polmag/
>
> GPG: 0x8BDC390B69033F52
