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parpool fails in deployed application

Asked by Vinayak Phalke on 29 Oct 2018
Latest activity Edited by Kristoffer Walker on 1 Jul 2019
I am building a parallel for loop (parfor) based deployed application. I have a parpool command before the parfor loop:
parpool('local', 4);
parfor a = 1:N ....
The code works with in MATLAB interacvtive, but on the deployed application, it errors out at the parpool line:
Error using parpool (line 113) The specified superclass 'parallel.internal.customattr.CustomPropTypes' contains a parse error, cannot be found on MATLAB's search path, or is shadowed by another file with the same name.

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What is your deployed application?MATLAB executable file?
I think you might need to set your parpool profile
However, in documentation, it is for MATLAB Compiler SDK.
Hi Nikilesh Chilkuru,
I would like to know that does MATLAB compiler need to do the same way?
Based on your suggestion, I saved my local profile (local.settings) and bundled that file in the deployed app. That seems to have fixed this issue. Thanks
Great. That's mean for MATLAB compiler, it need to do the same way as MATLAB Compiler SDK.

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3 Answers

Answer by Kevin Chng on 8 Nov 2018

To use parallel computing for standalone application (MATLAB Compiler SDK/MATLAB Compiler) , you may need to configure/change your code as below:

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Answer by Kristoffer Walker on 26 Jun 2019
Edited by Kristoffer Walker on 26 Jun 2019

Folks,
It would be great if this answer could be improved. I am having this issue now I believe, but I do not understand what a "local profile" is, how to generate such a settings file, and why I should bundle it for deployment in a completely different remote machine that will have a different number of cores and may not share any similarities with the local profile that was deployed with it. I have read the website links above.
Kris

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Hi Kris,
No worries, I think it is working with different PC up to 512 cores, provided it is utilizing the local computing resources. Not cloud/server resources (MATLAB Parallel Server).
How to get the setting files from local profile?
On top of your tab (Home>Parallel>Export)
reply.png
Then you will get the setting file.
Hi Kevin,
By the way, is there a way to have Matlab email me when someone has commented on a post I create? I don't seem to have that option turned on and I'd like to.
I am not using the Matlab Parallel Server. I just have a GUI that has a number of threads parameter. The callback on the nThreads parameter executes a parpool. The problem is that for some choices of nThreads (still below the max number of threads available to Matlab), the deployed version of the GUI will "beep" during the callback. The non-deployed version will not beep. No console errors are observed however. I interpret the beep to be due to parpool encoutering an issue. However, it still registers as reserving the correct number of threads. The callback is extremely simple:
function nThreads_Callback(hObject, eventdata, handles)
% hObject handle to nThreads (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
set(handles.Wavefield,'enable','off');
numCores = str2double(get(hObject, 'string'));
delete(gcp('nocreate'));
if (numCores > 1)
f = waitbar(0,'Creating parallel processing thread pool...');
parpool('local', numCores);
waitbar(0.5, f, 'Creating parallel processing thread pool...');
waitbar(1, f, 'Creating parallel processing thread pool...');
close(f);
end
set(handles.Wavefield,'enable','on');
Hi Kris,
Let me provide some documentation here for your reading:
Similar question has been asked in the past:
I tried it before personally, it is working for deployed application. For your question about :
Different remote machine that will have a different number of cores and may not share any similarities with the local profile that was deployed with it.
Frankly speaking, i'm not sure about it, but i think the local setting file should working for different machine.
Untitled.png
follow the documentation to get your local pc work with your deployed standalone application with parallel computing first.
later, we can try to execute the standalone application in different pc. I think it should be working. Let me know, i'm interested to know it as well.
If you still encouter any issue, let me know, then i try spend some time to try it out.

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Answer by Kristoffer Walker on 1 Jul 2019
Edited by Kristoffer Walker on 1 Jul 2019

Hi Kevin,
So I've looked more carefully at this and created a simple example to demo the problem. Just create a script "testApp.m". Include in it a call to function testAppFunc(), which inside it only does a "parpool(2)". Put some fprintf statements in there for correlation purposes. Then compile it with Application Compiler and test the testApp.exe in for_redistribution_files_only directory by launching from a PowerShell. You will hear the beep. Why does this happen and how can I stop it? This only happens the first time parpool is executed from a deployed app. It does not happen during subsequent calls to parpool in the same instance of the deployed app. It also does not happen in the non-deployed app at any time.
BTW, saving the settings.local file did not help (but thanks for those links to the instructions).
Kris

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