When I've been in that situation I have solved the problem with a lock on a temporary file.
If you need any more help, please let me know. I probably still have some examples around. best, Manuel 2017-09-03 15:02 GMT+02:00 Jordi A. Gómez <jordi.an...@bsc.es>: > Hello, > > I am developing a Spank plugin which starts a privileged process once per > node. This process will perform some work that require privileges like write > frequency, read devices, etc. > > I know I have the option of run it when Slurm Daemon is started in a node > and loads the Spank plugin. But I would prefer just to run it when its > necesary using some flag (srun --flag). > > Because I want to start it one time per node I'm thinking which could be the > best way to achieve that. In remote context I have the function > slurm_spank_task_init_privileged(), but it's executed by every node task and > I want to start it just once, just one process instance. These are my > possibilies: > > 1) Using little maths to get the number of tasks per node and calc the > minimum task number, which would be my selected task. For example, 4 tasks > and 2 nodes, the tasks 0 and 2 would run my privileged process. But I'm not > pretty sure that task numbers will follow always this pattern. And of course > is someone runs 3 tasks in first node and 1 in the second one, this has no > sense. > > 2) Some kind of inter process sync, or file block... to prevent that no > other task in the same machine has started my process yet. > > Any better ideas? > > Thank you, > Jordi.
