The `execution:` Block

Component drivers require an execution: block to provide details about how to configure a component’s run-time environment, and how to run it.

Example block:

execution:
  batchargs:
    cores: 40
    debug: True
    exclusive: True
    export: NONE
    jobname: my-job
    memory: 4GB
    nodes: 1
    partition: p1
    queue: q1
    rundir: /path/to/rundir
    shell: /bin/bash
    stderr: /path/to/runscript.err
    stdout: /path/to/runscript.out
    tasks_per_node: 40
    walltime: 00:02:00
  envcmds:
    - module use /path/to/modulefiles
    - module load some_module
  executable: /path/to/sfc_climo_gen
  mpiargs:
    - "--export=ALL"
    - "--ntasks $SLURM_CPUS_ON_NODE"
  mpicmd: srun
  threads: 8

batchargs:

These entries map to job-scheduler directives sent to e.g. Slurm when a batch job is submitted via the --batch CLI switch or the batch=True API argument. The only required entry is walltime.

Shorthand names are provided for certain directives for each scheduler, and can be specified as-so along with appropriate values. Recognized names for each scheduler are:

LSF: jobname, memory, nodes, queue, shell, stdout, tasks_per_node, walltime
PBS: debug, jobname, memory, nodes, queue, shell, stdout, tasks_per_node, walltime
Slurm: cores, exclusive, export, jobname, memory, nodes, partition, queue, rundir, stderr, stdout, tasks_per_node, walltime

NB To enable threading when running components compiled with OpenMP support, set the execution: block’s threads: item (see below). Then uwtools will set the appropriate scheduler flag when making a batch request, and will set the OMP_NUM_THREADS environment variable in the execution environment.

Other, arbitrary directive key-value pairs can be provided exactly as they should appear in the batch runscript. For example

--nice: 100

could be specified to have the Slurm directive

#SBATCH --nice=100

included in the batch runscript.

envcmds:

An array (YAML sequence) of commands to execute in the run-time shell before the component executable is run.

executable:

The name of or path to the component’s executable.

mpiargs:

An array (YAML sequence) of string arguments that should follow the MPI launch program (mpiexec, srun, et al.) on the command line. This entry is only used when configuring parallel components.

mpicmd:

The MPI launch program (mpiexec, srun, et al.). This entry is only used when configuring parallel components.

threads:

For drivers implementing support, exports the OMP_NUM_THREADS environment variable to the execution environment, specifying the number of OpenMP threads to use when running the component. This entry is only used when configuring parallel components.

The execution: Block