Adding SLURM job arrays in documentation.

doc/sampler.rst

@@ -374,6 +374,7 @@ It makes sense to define a script for this as well:
      sbatch script_redis_worker.sh
    done
 
+
 Here, ``n_jobs`` would be the number of jobs submitted. When the job scheduler
 is based on qsub, e.g. SGE/UGE, instead use a script like
 
@@ -389,6 +390,30 @@ is based on qsub, e.g. SGE/UGE, instead use a script like
 and adapt the worker script. For both, there exist many more configuration
 options. For further details see the respective documentation.
 
+When submitting a large number of individual SLURM jobs (``n_jobs``), the
+scheduler could be overloaded, i.e. increased scheduling overhead may degrade
+the overall efficiency of the scheduling respectively performance  on the HPC system.
+
+As an alternative, consider to use SLURM job arrays. A SLURM job array is a feature
+to manage a collection of similar jobs efficiently using a single submission script.
+Each job in the array (task), shares the same job script but can operate on
+different inputs and parameters identified by an unique index ``${SLURM_ARRAY_TASK_ID}``.
+
+Furthermore, monitoring and job control is streamlined compared to numerous individual
+jobs scattered across the queue (scalability of job submission). SLURM is optimized to handle
+large job arrays efficiently and should thus be considered as an alternative to the
+submission of many individual, yet related or similar, jobs.
+
+
+.. code:: bash
+
+   sbatch --array=0-99 script_redis_worker script_redis_worker.sh ${SLURM_ARRAY_TASK_ID}
+
+Using ``--array`` one specifies the number of jobs (here ``n_jobs`` is manually set to 99, resulting in 100 tasks)
+and note that depending on the variable ``${SLURM_ARRAY_TASK_ID}`` the script ``script_redis_worker.sh`` could 
+handle for instance different input parameters or input files as identified by a unique index.
+
+
 Note that when planning for the number of overall redis workers, batches, and
 cpus per batch, also the parallelization on the level of the simulations has
 to be taken into account. Also, memory requirements should be checked in