Re: How to call stop from parallel foreach

[seany via Digitalmars-d-learn]

On Thursday, 24 June 2021 at 21:19:19 UTC, Ali Çehreli wrote:

On 6/24/21 1:41 PM, seany wrote:

> Is there any way to control the number of CPU cores used in
> parallelization ?

Yes. You have to create a task pool explicitly:

import std.parallelism;

void main() {
  enum threadCount = 2;
  auto myTaskPool = new TaskPool(threadCount);
  scope (exit) {
    myTaskPool.finish();
  }

  enum workUnitSize = 1; // Or 42 or something else. :)
  foreach (e; myTaskPool.parallel([ 1, 2, 3 ], workUnitSize)) {
    // ...
  }
}

I've touched on a few parallelism concepts at this point in a presentation:

  https://www.youtube.com/watch?v=dRORNQIB2wA&t=1332s

Ali

I tried this .

                int[][] pnts ;
                pnts.length = fld.length;

                enum threadCount = 2;
                auto prTaskPool = new TaskPool(threadCount);

                scope (exit) {
                        prTaskPool.finish();
                }

                enum workUnitSize = 1;

                foreach(i, fLine; prTaskPool.parallel(fld, workUnitSize)) {
                  //....
                }


This is throwing random segfaults.
CPU has 2 cores, but usage is not going above 37%

Even much deeper down in program, much further down the line...
And the location of segfault is random.