Is there a way for a worker to see how many workers are in the parpool?

Hi,

Is there a way for a worker to see how many workers are in a parpool?

Currently i have this, but i have to change the value of NumWorkers before the parpool is started and for the first pctRunOnAll.

 NumWorkers = 32;
 ParallelPool  = parpool(NumWorkers);
 pctRunOnAll NumWorkers = 32;
 pctRunOnAll ParaScript

I know that i can do..

ParallelPool.NumWorkers

..in the parent script but this doesn't work in a worker.

Thanks

Answer 1

[Harsh]

Hi Bobby,

The “pctRunOnAll” command runs the specified code on all workers. So in your code the command “pctRunOnAll NumWorkers = 32;” sets the “NumWorkers” variable for all the workers and you can access it directly.

You can check the following documentation link to understand how “pctRunOnAll” works - https://www.mathworks.com/help/parallel-computing/pctrunonall.html

Parallel pools of up to 2000 workers are supported but the actual number of workers depends on various factors. You can check the following documentation to learn more about this topic - https://www.mathworks.com/help/parallel-computing/run-code-on-parallel-pools.html#bufclig-1:~:text=the%20period%20key).-,Factors%20That%20Affect%20Pool%20Size,-Parallel%20Computing%20Toolbox

Answer 2

[埃博拉酱]

It is recommended that you use spmd instead of pctRunOnAll. In a spmd block, you can easily get the parallel pool size using spmdSize.