why does (ga + parallel + global variables + sub2ind) fail?
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Jochen Schuettler
il 9 Set 2016
Risposto: Jochen Schuettler
il 12 Set 2016
When optimizing with ga and parallel computing, a sub2ind call using globals fails (subscript vectors must be of same size), but when doing it in serial, it doesn't fail. Why?
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Matt J
il 9 Set 2016
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Walter Roberson
il 11 Set 2016
Note that the above discussion is only for serial computing. The considerations are a bit different for parallel computing, where each worker must have a copy of the data because they are different processes.
Matt J
il 11 Set 2016
Modificato: Matt J
il 11 Set 2016
The discussion still applies to parallel computing if we're not talking about the one-time cost of broadcasting constant data to the workers. The OP seems to think that arguments passed to the fitness function will be copied "again and again" each time the fitness function is called. That is not true, even on parallel workers
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Walter Roberson
il 10 Set 2016
Global variables are never copied to parallel workers.
You might be able to take advantage of parallel.pool.Constant or of parfevalOnAll() to initialize the variable on all of the workers.
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Walter Roberson
il 11 Set 2016
If you have especially large shared data, you could also use the File Exchange contribution https://www.mathworks.com/matlabcentral/fileexchange/28572-sharedmatrix to use shared memory. This will only work if the compute nodes are on the same host, though
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