Balsam: HPC Workflows & Edge Service

Balsam allows you to manage a database of workflows with simple command-line interfaces and a Python API. As you populate the database, the Balsam service can automatically reserve bundles of tasks and batch-schedule them for parallel execution. Inside each batch job, the Balsam launcher monitors available resources, launches applications, and sends status updates back to the database.

Balsam is designed to minimize user “buy-in” and cognitive overhead. You don’t have to learn an API or write any glue code to acheive throughput with existing applications. In fact, it’s arguably faster and easier to run a simple app several times using Balsam than by writing an ensemble job script:

$ balsam app --name SayHello --executable "echo hello,"
$ for i in {1..10}
> do
>  balsam job --name hi$i --workflow test --application SayHello --args "world $i"
> done
$ balsam submit-launch -A Project -q Queue -t 5 -n 2 --job-mode=serial


  • Applications require zero modification and run as-is with Balsam

  • Launch MPI applications or pack several non-MPI tasks-per-node

  • Run apps on bare metal or inside a Singularity container

  • Flexible Python API and command-line interfaces for workflow management

  • Execution is load balanced and resilient to task faults. Errors are automatically recorded to database for quick lookup and debugging of workflows

  • Scheduled jobs can overlap in time; launchers cooperatively consume work from the same database

  • Multi-user workflow management: collaborators on the same project can add tasks and submit launcher jobs using the same database

The Balsam API enables a variety of scenarios beyond the independent bag-of-tasks:

  • Add task dependencies to form DAGs

  • Program dynamic workflows: some tasks spawn or kill other tasks at runtime

  • Remotely submit workflows, track their progress, and coordinate data movement tasks

Indices and tables