matlab R2023a parallel computing toolbox is not working

I am using Matlab R2023a and R2023b with parallel computing toolbox on Mac OS Ventura 13.5.1 (22G90). It used to work well, but without reason, the parallel stops working. I seems it just use one core as the order of the processed files is reversed with regard to that feed into the for loop.

I tried to re-install parallel computing toolbox. It worked for one time, but then stops working even when I re-install the toolbox again. I also tried re-install matlab. Still not working.

For R2023b (which runs natively on M1), I still can re-install the toolbox and get it run (still not work after I restart matlab). But it does not work for R2023a.

When I run parpool:

>> parpool

Unrecognized function or variable 'parpool'.

Or start parpool by clicking Start Parallel Pool:

Unrecognized function or variable 'parallel.internal.ui.PoolHelper.startPool'.

This used to work, but failed without any changes in search path or new toolboxes.

Could anyone give a hint?

Some updates:

I tried to install Matlab 2020a, and 2024a on my mac in different folders (/Application and ~/Documents). But this problem still exists...

It seem the installation is not complete as I see the following message on startup:

Warning: Name is nonexistent or not a directory: /Users/XinNiuAdmin/Documents/MATLAB/MATLAB_R2024a.app/toolbox/matlab/datatools/desktop_importtool/matlab 
Warning: Name is nonexistent or not a directory: /Users/XinNiuAdmin/Documents/MATLAB/MATLAB_R2024a.app/toolbox/matlab/helptools/reference 
Warning: Name is nonexistent or not a directory: /Users/XinNiuAdmin/Documents/MATLAB/MATLAB_R2024a.app/toolbox/matlab/mpm 
Warning: Name is nonexistent or not a directory: /Users/XinNiuAdmin/Documents/MATLAB/MATLAB_R2024a.app/toolbox/matlab/project/example 
Warning: Name is nonexistent or not a directory: /Users/XinNiuAdmin/Documents/MATLAB/MATLAB_R2024a.app/toolbox/matlab/project/toolstrip 
Warning: Name is nonexistent or not a directory: /Users/XinNiuAdmin/Documents/MATLAB/MATLAB_R2024a.app/toolbox/matlab/project/views/labels 
Warning: Name is nonexistent or not a directory: /Users/XinNiuAdmin/Documents/MATLAB/MATLAB_R2024a.app/toolbox/matlab/testframework/mock/core/masked 
Warning: Name is nonexistent or not a directory: /Users/XinNiuAdmin/Documents/MATLAB/MATLAB_R2024a.app/toolbox/matlab/testframework/unittest/core/masked 
Warning: Name is nonexistent or not a directory: /Users/XinNiuAdmin/Documents/MATLAB/MATLAB_R2024a.app/toolbox/matlab/webcam 
Warning: Name is nonexistent or not a directory: /Users/XinNiuAdmin/Documents/MATLAB/MATLAB_R2024a.app/toolbox/simulink/configset/derived
...

Also, If I install it on /Application. It will keep asking allow a access my documents folder for both the version I start and the other version which is running.

Is there a walk around for the standard installation ?

Thanks for reading my message.

[Walter Roberson]

"I seems it just use one core as the order of the processed files is reversed with regard to that feed into the for loop."

That is how parfor is defined to work when Parallel Computing Toolbox is not installed (or not licensed)

[Xin Niu]

Thanks for letting me know. But I am sure I have the license and the toolbox is installed. It used to work well. Then by unknown reason, it only works when I re-install the toolbox. Now it just won't work...

[Edric Ellis]

It looks like your installation has got messed up somehow. I suggest contacting Install Support to resolve this.

[Xin Niu]

Will do thank you!

Answer 1

[Xin Niu]

Just got response from IT from mathworks:

Thank you for contacting MathWorks Support.

If the Parallel Computing Toolbox is not showing after installing it, this could be due to a pathing issue in MATLAB. To try and fix this, let's restore MATLAB's default path and rehash the toolbox cache.

First, it is important to take a backup of the current 'pathdef.m' file, which can be located by executing the following command in the MATLAB Command Window:

>> which -all pathdef

Ensure that you make a copy of the file by copying it in a location different than its current folder. This is because the steps of this procedure involve regenerating the MATLAB Search Path including resetting the 'pathdef.m' file in its initial state. This procedure will further remove custom paths you may have added in the MATLAB Search Path. Note: If you have multiple files show in the output of this command, remove any files that are not on the $MATLAB/toolbox/local path. MATLAB may encounter issues if it reads multiple pathdef.m files.

After taking the backup, please execute the following commands in the MATLAB Command Window to restore the default MATLAB Search Path and rehash the toolbox cache:

>> restoredefaultpath

>> rehash toolboxcache

After running these commands, please use MATLAB to see if the initial issue was resolved. Then you may want to save the new MATLAB search path to the 'pathdef.m' file by executing the following command:

>> savepath

Note that the above commands will reset any custom paths you have set. For more information, please refer to the following article:

How will running the "restoredefaultpath" and "savepath" commands affect my custom paths and how do I back up my custom paths?

https://www.mathworks.com/matlabcentral/answers/166871

If you have any further questions, please do not hesitate to email me back.

Please be sure to keep the REF ID included at the bottom of this email intact when replying to this message.