Parse UNLIMITED and NOT_SET time in SLURM scheduler

[greschd]

When running things on a SLURM scheduler, my log is usually cluttered with

10/01/2019 03:58:01 PM <69426> aiida.scheduler.slurm: [WARNING] Unrecognized format for time string 'UNLIMITED'
10/01/2019 03:58:01 PM <69426> aiida.scheduler.slurm: [WARNING] Error parsing the time limit for job id 622565

This should be easy to fix: In the _convert_time method of the SLURM plugin, return float('inf') if the string matches 'UNLIMITED' (and None for 'NOT_SET', which is also possible according to SLURM docs).

Does anyone know if this could have consequences down the line because the places where this is used (this_job.requested_wallclock_time_seconds and this_job.wallclock_time_seconds) are assumed to be int? They both go into the JobInfo, and None and float('inf') are JSON-serializable.

[sphuber]

pinging @giovannipizzi who might know

[giovannipizzi]

float(inf) will not work currently because of our validation that we discuss in #2412 and is not yet decided.
Maybe, even if a bit ugly and as if we were in the '70s, we can set -1 in the UNLIMITED case (and document it)?

[greschd]

Hmm, what about setting it to 2147483647 (maximum for the "normal" 4-byte signed integer in postgres, and roughly 68 years)?

The only issue I see with -1 is what will happen if someone decides to do comparisons on that.

[giovannipizzi]

I see - also that however it a bit strange and people might not understand what it means.
Is there a real difference between UNSET and UNLIMITED? What if we put None in both?

[greschd]

TBH I've never actually seen NOT_SET in practice, but the docs say it happens when "the value is not yet established". UNLIMITED means exactly that, these are jobs that won't time out.

[greschd]

I also don't mind just keeping this open until we've moved on #2412. It's really not a big nuisance, and that might be better than a kludgy implementation now.

[sphuber]

In the light of the decision on #2412 that inf will not be supported in attributes, should we set UNSET and UNLIMITED as None?

[giovannipizzi]

Maybe indeed the best thing is to set it to None for UNSET and to a large integer as @greschd suggested for UNLIMITED, that is closer to what actually means, distinguishes the two and allows for the correct comparisons? Of course we need to discuss why in the docs.

[greschd]

Suggestions welcome for which magic high number should get the honors. Some possibilities:

• 2147483647 == 2**31 - 1: maximum 32-bit signed int, as suggested above
• 9223372036854775807== 2**63 - 1: same, but for 64-bit signed int, as suggested above. Also corresponds to sys.maxsize on most systems
• Something more recognizable to a human as a "very large number", e.g. 9999999999.
• 3093292800 == -int(datetime.datetime(year=1871,month=12,day=24).timestamp())

[sphuber]

* `3093292800 == -int(datetime.datetime(year=1871,month=12,day=24).timestamp())`

👍 I like it!

[greschd]

Well, somebody needs to investigate the exact time, and of course I've ignored the time zone as well. Can we get funding for this?