# 5. Modify Submit Parameters¶

In some cases the MATLAB app batch job fails to submit to the given cluster or you are not happy with the default chosen submission parameters. This section explains how to modify the submission parameters.

The main responsibility of the submit.yml.erb file (Job Submission) located in the root of the app is for modifying the underlying batch script that is generated from an internal template and its submission parameters.

Note

The .erb file extension will cause the YAML configuration file to be processed using the eRuby (Embedded Ruby) templating system. This allows you to embed Ruby code into the YAML configuration file for flow control, variable substitution, validation, and more.

The simplest submit.yml.erb will look like:

# ~/ondemand/dev/bc_my_center_matlab/submit.yml.erb
---
batch_connect:
template: "vnc"


Which only describes which internal template to use when generating the batch script. From here we can add more options to the batch script, such as:

# ~/ondemand/dev/bc_my_center_matlab/submit.yml.erb
---
batch_connect:
template: "vnc"
set_host: "host=$(hostname -A | awk '{print$2}')"


where we override the bash script used to determine the host name of the compute node from within a running batch job.

You can learn more about possible batch_connect options here:

http://www.rubydoc.info/gems/ood_core/OodCore%2FBatchConnect%2FTemplate:initialize

Warning

It is recommended any global batch_connect attributes be defined in the corresponding cluster configuration file under:

/etc/ood/config/clusters.d/my_cluster.yml


There is further discussion on this under Modify Cluster Configuration.

But in most cases you will want to change the actual job submission parameters (e.g., node type). These are defined under the script option as:

# ~/ondemand/dev/bc_my_center_matlab/submit.yml.erb
---
batch_connect:
template: "vnc"
script:
...


You can read more about all the available script options here:

http://www.rubydoc.info/gems/ood_core/OodCore/Job/Script

Although in most cases you will want to modify the native attribute, which is resource manager dependent. Some examples are given below.

Note

It is recommended you commit the changes you made to submit.yml.erb to git.

git commit submit.yml.erb -m 'updated batch job options'


## Slurm¶

For Slurm, you can choose the features on a requested node with:

# ~/ondemand/dev/bc_my_center_matlab/submit.yml.erb
---
batch_connect:
template: "vnc"
script:
native:
- "-N"
- "<%= bc_num_slots.blank? ? 1 : bc_num_slots.to_i %>"
- "-C"
- "c12"


where we define the sbatch parameters as an array under script and native.

Note

The native attribute is an array of command line arguments. So the above example is equivalent to appending to sbatch:

sbatch ... -N <bc_num_slots> -C c12


The bc_num_slots shown above located within the ERB syntax is the value returned from web form for “Number of nodes”. We check if it is blank and return a valid number (since it wouldn’t make sense to return 0).

## Torque¶

For Torque, you can choose processors-per-node with:

# ~/ondemand/dev/bc_my_center_matlab/submit.yml.erb
---
batch_connect:
template: "vnc"
script:
native:
resources:
nodes: "<%= bc_num_slots.blank? ? 1 : bc_num_slots.to_i %>:ppn=28"


Note

See http://www.rubydoc.info/gems/pbs/PBS%2FBatch:submit_script for more information on possible values for the native attribute.

The bc_num_slots shown above located within the ERB syntax is the value returned from web form for “Number of nodes”. We check if it is blank and return a valid number (since it wouldn’t make sense to return 0).

## PBS Professional¶

For most cases of PBS Professional you will want to modify how the bc_num_slots (number of CPUs on a single node) is submitted to the batch server.

This can be specified as such:

# ~/ondemand/dev/bc_my_center_matlab/submit.yml.erb
---
batch_connect:
template: "vnc"
script:
native:
- "-l"
- "select=1:ncpus=<%= bc_num_slots.blank? ? 1 : bc_num_slots.to_i %>"


where we define the qsub parameters as an array under script and native.

If you would like to mimic how Torque handles bc_num_slots (number of nodes), then we will first need to change the form label of bc_num_slots that the user sees in the form. This can be done by adding to the form configuration file the highlighted lines:

# ~/ondemand/dev/bc_my_center_matlab/form.yml
---
cluster: "cluster1"
attributes:
modules: "python"
extra_jupyter_args: ""
bc_num_slots:
label: "Number of nodes"
form:
- modules
- extra_jupyter_args
- bc_num_hours
- bc_num_slots
- bc_account
- bc_queue
- bc_email_on_started


Now when we click Launch Jupyter Notebook from the app details view, the form in the browser will have the new label “Number of nodes” instead of “Number of CPUs on a single node”.

Next we will need to handle how we submit the bc_num_slots since it means something different now. So we modify the job submission configuration file as such:

# ~/ondemand/dev/bc_my_center_matlab/submit.yml.erb
---
batch_connect:
template: "vnc"
script:
native:
- "-l"
- "select=<%= bc_num_slots.blank? ? 1 : bc_num_slots.to_i %>:ncpus=28"


where we replace ncpus=28 with the correct number for your cluster. You can also append mem=...gb to the select=... statement if you’d like.

Note

The native attribute is an array of command line arguments. So the above example is equivalent to appending to qsub:

qsub ... -l select=<bc_num_slots>:ncpus=28


The bc_num_slots shown above located within the ERB syntax is the value returned from web form for “Number of nodes”. We check if it is blank and return a valid number (since it wouldn’t make sense to return 0).

## Other Resource Manager¶

For most of our other adapters (aside from Torque) the native attribute is an array of command line arguments formatted similarly to the Slurm example above.