MATLAB: How to get parpool to pause at breakpoints

debugparallelParallel Computing Toolboxspmd

When I do "parpool('local',4)" Matlab ignores my breakpoints so that I can't debug my parallel code. This is within an spmd section.

Best Answer

Unfortunately, it is not possible to use the MATLAB debugger to debug code running on workers. The normal workaround is to liberally sprinkle fprintf or disp calls through your code that will be run on the workers. Often this is sufficient to narrow down the problematic portion of code to something you can debug on the client.

Related Solutions

MATLAB: How to debug C-Code that runs on a Worker with the Parallel Computing Toolbox

You can debug the C code that runs in a MATLAB process launched the parallel computing toolbox with a C-compiler such as “Microsoft Visual C++”.

For this, follow the below steps:

1. Compile your c code with Visual C++ with a debug flag.

2. Start a of MATLAB sessions for parallel computation

3. Find out the process id of the MATLAB process you need to debug. This can be done with following code:

 spmd    % By default creates pool and uses all workers
 feature getpid
 end

4. Open the c file with Visual Studio and place break point in it.

5. Attach Visual Studio to the corresponding MATLAB process

6. Run and debug your c-code in the corresponding MATLAB worker

MATLAB: Breakpoints

Assuming your breakpoints are sorted (I'll call them breakpoints), you could do something like this:

x = 0.55;
find(breakpoints<x,1,'last')

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Related Solutions

MATLAB: How to debug C-Code that runs on a Worker with the Parallel Computing Toolbox

MATLAB: Breakpoints

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