Local Prefect Server Plugin#

Added in version 1.4.15: Beta version. Works, but some minor rough edges/bugs may be encountered.

This prefect environment can be selected via --execenv=prefect.localserver. This plugin defines the following prefect artifacts:

  • sierra/local flow to execute all Experimental Runs in each Experiment in parallel.

  • sierra-pool work pool which the prefect workers live in. The # workers is determined by the selected Engine.

  • sierra-queue work queue which the SIERRA prefect workers pull tasks from.

Obviously, if you use this execution environment, don't define artifacts with the same name in prefect or things will (probably) not work.

A local prefect server is spun up for the Batch Experiment. Currently, multiple SIERRA users using this plugin on the same server is not supported, though it could be easily if randomized ports are used.

Warning

As of 2025/7/29 prefect=3.4.3, there does not appear to be any way to limit the concurrency at the task-level (which is what SIERRA uses), so it is not currently possible to limit # simultaneously active runs/simulations. This means that (a) multiple users using the execution environment on the same server will not work well, and (b) simulation engines which use multiple threads for a single experimental run can easily overload the local machine if --n-runs >= # cores on machine / # threads per run.

Prefect-SIERRA interface#

Prefect environment variable

SIERRA context

Command line override

PREFECT_API_URL

The URL the server is accessible at. Not currently configurable. The docs say it's configurable, but it doesn't work afaict. This means that multiple concurrent users of SIERRA using this plugin will probably not work.

N/A

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