MATLAB: How to stop at warning within parfor

debugparforwarning

My code includes a parfor loop which gives a few warnings while executing. I want to troubleshoot these but couldn't find a way to stop code at warning while saving the parameters.

I have tried dbstop if warning but it does not work within parfor loop.

Best Answer

You cannot debug code running on matlabpool workers, however you can run your code with matlabpool closed and debug that.

What is the warning you're seeing?

Related Solutions

MATLAB: Distributing arrays to workers for local processing

Hello. If you are able to successfully open a matlabpool with your installation of R2011b, then you must have the Parallel Computing Toolbox. In that case, the getLocalPart function should also be available to you. What is the output from typing the following at the MATLAB command line:

which getLocalPart

Assuming that you can get the issue with getLocalPart sorted out (perhaps by calling technical support), this is how you would proceed with distributed arrys/spmd:

matlabpool open 100 % this will open 100 workers 
                    % using your default configuration
% I assume that myMat was already loaded as a standard MATLAB array
size(myMat)     % You've stated that myMat is 800000 x 2     
% There are a lot of rows, so let's use codistributor1d to 
% distribute the rows across all the workers in the pool.  This must
% be done inside the spmd block because that's where 
% codistributed arrays and codistributors live.
spmd 
  codist = codistributor1d(1); % Create a scheme to distribute the first
                               % dimension of a matrix (its rows) as evenly as
                               % possible across all the workers in the 
                               % pool    
  myMatdb = codistributed(myMat, codist);  % Use the scheme to create 
                                           % distributed data
  chunk_of_data = getLocalPart(myMatdb);   % Each worker operates on its data 
  [out_of_chunk] = objFun(params, chunk_of_data);
  fullOutput = codistributed.build(out_of_chunk, codist); % Create a new 
                                                          % array from the 
                                                          % local outputs. I
                                                          % assume that
                                                          % out_of_chunk is
                                                          % the same size as 
                                                          % chunk_of_data on
                                                          % each worker so
                                                          % that the
                                                          % codistributor can
                                                          % be reused.
end  
% fullOutput and myMatdb can be used as distributed arrays outside of the spmd block

You can find more information here:

help getLocalPart
help codistributor.build

MATLAB: Suppress error warnings in matlab (when using parfor loop)

If the warning is being generated on the workers, you need to apply the warning suppression there too. You could do it like so:

spmd
  warning('off','curvefit:fit:noStartPoint')
end

Best Answer

Related Solutions

MATLAB: Distributing arrays to workers for local processing

MATLAB: Suppress error warnings in matlab (when using parfor loop)

Related Question