Today I'm asking a more theoretical question, since I can't quite grasp this one too well.

Let's say I want 3 while-loops running in parallel, without getting in the way of each other, how would I do that?

With std.parallel of course, but that's where I get confused, perhaps someone could enlighten me?

On Friday, 17 January 2014 at 21:07:46 UTC, Mineko wrote:

> Let's say I want 3 while-loops running in parallel, without getting in the way of each other, how would I do that?

On the same set of data? That's optimistic if one of the loops writes :) Otherwise, you could just create three tasks, one per loop.

On Friday, 17 January 2014 at 21:07:46 UTC, Mineko wrote:
> Today I'm asking a more theoretical question, since I can't quite grasp this one too well.
>
> Let's say I want 3 while-loops running in parallel, without getting in the way of each other, how would I do that?
>
> With std.parallel of course, but that's where I get confused, perhaps someone could enlighten me?

Hi,

> std.parallel
You mean std.parallelism.

Assuming your code is thread safe[1], you would have each of
these while loops in a delegate or function, and create a
Task[2]. Once the Task is created, use the executeInNewThread
function. You can use yieldForce to wait on it. However, if you
don't *really* need while loops, take a look at creating a
TaskPool and using a parallel foreach, reduce, map, etc. They are
also in std.parallelism.

However, it's worth noting that there is also std.concurrency[3]
which may be a better approach if your threads need to
communicate. core.thread/core.atomic are useful if you need lower
level control.

If your code is not thread safe, look into synchronized
statement, core.atomic, and possibly core.sync.* and make it
thread safe.

[1]: http://en.wikipedia.org/wiki/Thread_safety
[2]: http://dlang.org/phobos/std_parallelism.html#.Task
[3]: http://dlang.org/phobos/std_concurrency.html

Regards,
Kelet

On 01/17/2014 01:28 PM, Kelet wrote:

> create a Task[2]. Once the Task is created, use the executeInNewThread
> function. You can use yieldForce to wait on it.

That's what I thought initially as well but then I realized that it can be even simpler than that:

import std.stdio;
import std.parallelism;

void main()
{
    // All of these loops can be free-standing functions as well

    long sum1 = 0;
    auto loop1 = {
        foreach (number; 0 .. 100) {
            sum1 += number;
        }
    };

    long sum2 = 0;
    auto loop2 = {
        foreach (number; 0 .. 100) {
            sum2 += number;
        }
    };

    foreach (loop; [ loop1, loop2 ].parallel) {
        loop();
    }

    writefln("sum1: %s, sum2: %s", sum1, sum2);
}

Ali