Is there any reason utils/schedules.py's is_valid_cron_string() is limiting the cron config to not include the seconds field which is supported by the underlying cronitor lib? Dagster seems to work just fine when using subsecond cron schedules (if I bypass the check) such as * * * * * */5. Comment in this function says that it is purposely limiting this to not support seconds resolution. Any real reason for this?

There might not be logical limitations. I think this might historically stem from when we allowed for plugging in to the

SystemCronScheduler

which has since been deprecated. One thing to note is that just based on the way the scheduler daemon is organized, I’d be concerned about continuously falling behind if you had schedules firing every second.