MATLAB Answers

why does (ga + parallel + global variables + sub2ind) fail?

2 views (last 30 days)
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?

Accepted Answer

Matt J
Matt J on 9 Sep 2016
Probably because of the dangers of using global variables.
  5 Comments
Matt J
Matt J on 11 Sep 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

Sign in to comment.

More Answers (2)

Walter Roberson
Walter Roberson on 10 Sep 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.
  1 Comment
Walter Roberson
Walter Roberson on 11 Sep 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

Sign in to comment.


Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by