why matlab is using all cores when no parallel pool is created

Hi

Something weird is happening on my matlab code.

I'm using AMD Ryzen Threadripper 2990WX (32 physical cores).

I have parallel computing but there is no parallel thing in my code, so when the code is running, matlab should use single core.

I was running three matlab program with that code with different inputs.

Then, my computer seems too slow so I checked task manager, the matlab processes are using more than 60% of cpu.

What's going on here...?

Answer 1

[Steven Lord]

Many operations in MATLAB, when it would be beneficial to use multiple threads in their computation, are multithreaded even without Parallel Computing Toolbox. Generally this means you're operating on a large enough set of data.

If you wanted MATLAB to not multithread you could start it with the -singleCompThread startup option or call the maxNumCompThreads function. Note that each of these affect computational threads; MATLAB can use non-computational threads (for things like the Desktop or graphics operations) even if you've limited the number of computational threads.