Matlab 2016 parpool only connects to 1 worker

My machine has 8 cores. I have tried changing the number of workers in parallel preferences, tried making a new local profile, tried parpool(8); none of these seem to work. I have Matlab 9.0.0.341360 (R2016a). My machine has windows 10. I tried parpool on a different machine with 16 cores and Matlab 2016a, encountered the same problem. On this machine, the validation step of a new cluster connected to 16 workers in job test and SPMD job test, but back to 1 worker in actual parpool. I checked bug reports, and this does not seem to be a known bug. What can I do to use the maximum number of workers?

[Edric Ellis]

This is definitely not expected. Please contact MathWorks support to resolve this.

Answer 1

[Harsh]

Make sure the Parallel Computing Toolbox is installed and licensed for use by running the following commands: https://www.mathworks.com/matlabcentral/answers/225996-how-can-i-tell-if-the-parallel-computing-toolbox-installed#answer_264780

I assume you have run the cluster validation for the "local" profile and have the "Preferred number of workers in a parallel pool" property set to >= number of cores on your machine. Instructions for this can be found here:

https://www.mathworks.com/help/distcomp/parallel-preferences.html

https://www.mathworks.com/help/distcomp/discover-clusters-and-use-cluster-profiles.html#brrzq8d-1

Run the following command and make sure the machine has the expected number of cores:

>> feature('numcores')

You can also manually start a parallel pool and configure the number of workers. For example:

>> obj = parcluster
>> obj.NumWorkers = 2
>> parpool(2)

Having verified all the above, if the issue still persists, please contact technical support here: https://www.mathworks.com/support/contact_us/

Please be sure to provide a detailed description of the issue and attach any relevant files / code / examples required to investigate the issue.

Answer 2

[Khadija Bouaita]

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