https://prefect.io logo
#prefect-community
Title
# prefect-community
j

Jack Sundberg

08/22/2020, 6:27 PM
Hey everyone, I apologize in advance for how much I wrote here... I realize that I'm attempting to use Prefect in a manner that it's not originally designed for, so I have a longer explanation of why I'm doing this below. While most users are coming from AirFlow, I'm trying to transition from FireWorks (https://github.com/materialsproject/fireworks). So here's my main question: Can I setup Prefect with many Agents that make a single task request and then terminate? In addition, when an agent is started and no tasks are ready for execution, the Agent will terminate. If this is possible, what would you estimate for the overhead per task? I would expect the main overhead comes from Agent connection to the Prefect Cloud/Server. This may sound like an inefficient use of Prefect, but it is intentional. Fireworks is designed with this setup in mind and is thus limited to 6/tasks per second -- this is acceptable because the average task submitted via FireWorks is on the hour timescale. I'm a materials chemistry researcher at UNC, where I must submit tasks as individual SLURM jobs, each with their own time and memory restrictions. These tasks (DFT energy calculations) range drastically in their required resources (one could be <1GB while another >200GB memory), launch in parallel using mpirun, and require their own isolated directory. I could use a single Executor like Dask, which supports queues like SLURM, but this would cause a number of problems for me. Dask holds onto worker resources indefinitely, which research-cluster admins don't want. If there are no tasks ready to execute, the cluster's resources should be released. Dask (as far as I'm aware) does not allow for setting time/memory limits on a per-task basis. And I'm unsure how Dask will handle tasks that execute via mpirun and also implement isolated directories per task. Fireworks was made by the materials chemistry community specifically for this. In the setup, you constantly submit SLURM jobs. Once a SLURM job makes it through the queue, the job itself simply starts an Agent, runs a single task, and then closes. This submission architecture is something I would like to replicate with Prefect. Fireworks has a number of limitations that I think Prefect can fix - such as their WorkFlow classes and meta-database (MongoDB) - so I'm looking into switching over. Again, sorry for the long write! Thanks for reading through, and let me know if you think a multi-Agent approach is possible with Prefect. -Jack
c

Chris White

08/22/2020, 6:28 PM
Hi Jack and welcome! because of the detailed nature of the question, this might be better suited for a GitHub Discussion: https://github.com/PrefectHQ/prefect/discussions
j

Jack Sundberg

08/22/2020, 6:29 PM
haha gotcha. I'll copy this over there. Thanks
c

Chris White

08/22/2020, 6:29 PM
no worries - we will respond in the discussion thread! 👍