Running-the-jobs/Multi-threaded-jobs.md

+### Code example
+
+We will use an [OpenMP](https://en.wikipedia.org/wiki/OpenMP) job as example, you can create a [openmp.cpp](https://gitlab.oca.eu/DSI/HPC/blob/master/SLURM/multithread/openmp.cpp) test program and compile it with:
+```
+$icpc -qopenmp ./openmp.cpp -o openmp
+$
+```
+the '-qopenmp' option will tell the compiler to recognize the [OpenMP pragmas](https://en.wikipedia.org/wiki/OpenMP#Clauses).
+
+This OpenMP example will automatically read the **OMP_NUM_THREADS** environment variable to detect the number of thread to use. Other multitread programs may have other ways to get that information.
+
+### Slurm script
+
+We will use the [multithread.slurm](https://gitlab.oca.eu/DSI/HPC/blob/master/SLURM/multithread/multithread.slurm) script to dispatch our job. Slurm option will be provided on the command line for flexibility, but would typically be specified in the script through the `#SBATCH <option>` directive
+
+### Examples
+ * Running 1 task with only 1 core:
+```
+$ sbatch --partition fdr --cpus-per-task=1 ./multithread.slurm 
+Submitted batch job 15292873
+$  more slurm-15292873.out 
+SLURM_CPUS_PER_TASK 1
+OMP_NUM_THREADS: 1
+Hi world, we were 1 on the job.
+$ 
+```
+ * Running one task with 10 cores
+```
+$sbatch --partition fdr --cpus-per-task=10 ./multithread.slurm 
+Submitted batch job 15292876
+$more slurm-1529287      
+slurm-15292873.out  slurm-15292876.out  
+$ more slurm-15292876.out 
+SLURM_CPUS_PER_TASK 10
+OMP_NUM_THREADS: 10
+Hi world, we were 10 on the job.
+$ 
+```
+ * If no node is available with the requested number of cores:
+```
+$ sbatch --partition fdr --cpus-per-task=50 ./multithread.slurm 
+sbatch: error: CPU count per node can not be satisfied
+sbatch: error: Batch job submission failed: Requested node configuration is not available
+$ 
+```
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