# SW:Matlab matlabsubmit

# Example 1: basic use

The following example shows the simplest use of matlabsubmit. It will execute matlab script *test.m* using default values for batch resources and Matlab resources. matlabsubmit will also print some useful information to the screen. As can be seen in the example, it will show the Matlab resources requested (e.g. #threads, #workers), the submit command that will be used to submit the job, the batch scheduler JobID, and the location of output generated by Matlab and the batch scheduler.

-bash-4.1$ matlabsubmit test.m =============================================== Running Matlab script with following parameters ----------------------------------------------- Script : test.m Workers : 0 Nodes : 1 #threads : 8 =============================================== sbatch -o MatlabSubmitLOG1/slurm.out --job-name=matlabsubmitID-1_test --ntasks=1 --ntasks-per-node=1 --cpus-per-task=8 --mem=16000 --time=02:00:00 MatlabSubmitLOG1/submission_script Submitted batch job 3759554 (from job_submit) your job is charged as below Project Account: 122839393845 Account Balance: 17504.211670 Requested SUs: 16 ----------------------------------------------- matlabsubmit ID : 1 Matlab output file : MatlabSubmitLOG1/matlab.log -bash-4.1$

The matlab script *test.m* has to be in the current directory. Control will be returned immediately after executing the matlabsubmit command. To check the run status or kill a job, use the respective batch scheduler commands (e.g. **squeue** and **scancel**). matlabsubmit will create a sub directory named **MatlabSubmitLOG<N>** (where **N** is the matlabsubmit ID). In this directory matlabsubmit will store all its relevant files; the generated batch script, matlab driver, and redirected output and error. A listing of this directory will show the following files:

**slurm.err**redirected error**slurm.out**redirected output (both LSF and Matlab)**matlab.log**redirected Matlab screen output**matlabsubmit_wrapper.m**Matlab code that sets #threads and calls user function**submission_script**the generated LSF batch script**batch_job_id-<SLURM_JOBID>**dummy file to show the actual Slurm job id this matlabsubmit job is associated to.

# Example 2: Utilizing Matlab workers (single node)

To utilize additional workers used by Matlab's parallel features such as *parfor*,*spmd*, and *distributed*, **matlabsubmit** provides an option to specify the number of workers. This is done using the *-w <N>* flag (where <N> represents the number of workers). The following example shows a simple case of using 8 workers.

-bash-4.1$ matlabsubmit -w 8 test.m Running Matlab script with following parameters ----------------------------------------------- Script : test.m Workers : 8 Nodes : 1 #threads : 1 =============================================== sbatch -o MatlabSubmitLOG2/slurm.out --job-name=matlabsubmitID-2_test --ntasks=9 --ntasks-per-node=9 --cpus-per-task=1 --mem=16000 --time=02:00:00 MatlabSubmitLOG2/submission_script Submitted batch job 3759571 (from job_submit) your job is charged as below Project Account: 122839393845 Account Balance: 17504.211670 Requested SUs: 18 ----------------------------------------------- matlabsubmit ID : 2 matlab output file : MatlabSubmitLOG2/matlab.log

In this example, **matlabsubmit** will first execute Matlab code to create a *parpool* with 8 workers (using the local profile). As can be seen in the output, in this case, **matlabsubmit** requests 9 cores: 1 core for the client and 8 cores for the workers. The only exception is when the user requests all the workers on a node ( 28 on terra). In that case, matlabsubmit will request all cores (instead of one extra for the client).

# Example 3: Utilizing Matlab workers (multi node)

**matlabsubmit** provides excellent options for Matlab runs that need more workers than fit a single node and/or when the Matlab workers need to be distributed among multiple nodes. Some examples for distributing workers among multiple nodes include

- hybrid runs: where every worker uses multiple computational threads
- memory requirements: where the job needs more memory than fits on a single node.
- GPU needs: where every worker needs to utilize the GPU on a node

The following example shows how to run a matlab simulation that utilizes 24 workers, where every node will run 4 workers (i.e. the workers will be distributed among 24/4 = 6 nodes).

-bash-4.1$ matlabsubmit -w 8 -p 4 test.m =============================================== Running Matlab script with following parameters ----------------------------------------------- Script : test.m Workers : 8 Nodes : 2 #threads : 1 =============================================== ... starting matlab batch. This might take some time. See MatlabSubmitLOG5/matlab-batch-commands.log ...Starting Matlab from host: tlogin-0502.cluster MATLAB is selecting SOFTWARE OPENGL rendering. < M A T L A B (R) > Copyright 1984-2019 The MathWorks, Inc. R2019b Update 3 (9.7.0.1261785) 64-bit (glnxa64) November 27, 2019 To get started, type doc. For product information, visit www.mathworks.com. ... Interactive Matlab session, multi threading reduced to 8 submitstring = '--cpus-per-task=1 --ntasks=9 --ntasks-per-node=4 --mem=5334 --time=2:00:00 ' -bash-4.1$

As can be seen the output is very different from the previous examples ( some of the ouput has been removed for readability). When a job uses multiple nodes the approach **matlabsubmit** uses is a bit different. **matlabsubmit** will start a regular *interactive* Matlab session and from within it will run the Matlab *batch* command using a specialized cluster profile. It will then exit Matlab while the Matlab script is executed on the compute nodes.

The contents of the MatlabSubmitLOG directory are also slightly different. A listing will show the following files:

**matlab-batch-commands.log**screen output from Matlab**matlabsubmit_driver.m**Matlab code that sets up the cluster profile and calls Matlab*batch***matlabsubmit_wrapper.m**Matlab code that sets #threads and calls user function**submission_script**The actual command to start Matlab

In addition to the MatlabSubmitLOG directory created by **matlabsubmit**, Matlab will also create a directory named **Job<N>** used by the cluster profile to store metadata, log files, and screen output. The ***.diary.txt** text files will show screen output for the client and all the workers. All the Job<N> directories can be found in your $SCRATCH/MatlabJobs/<PROFILE> directory where <PROFILE> is the name of the used cluster profile. For R2019b it will be *$SCRATCH/MatlabJobs/TAMU2019b*. Note: for older versions, the profile is always *TAMU*