Performance issue with fiber

[Daniel Kozak]

On Wed, Jul 28, 2021 at 11:41 PM hanabi1224 via Digitalmars-d-learn <
digitalmars-d-learn at puremagic.com> wrote:

> On Wednesday, 28 July 2021 at 16:26:49 UTC, drug wrote:
> > I profiled the provided example (not `FiberScheduler`) using
> > perf. Both dmd and ldc2 gave the same result - `void
> > filterInner(int, int)` took ~90% of the run time. The time was
> > divided between:
> >       `int std.concurrency.receiveOnly!(int).receiveOnly()` - 58%
> >       `void std.concurrency.send!(int).send(std.concurrency.Tid,
> > int)` - 31%
> >
> > So most of the time is messages passing.
> >
> > Between the fibers creating took very few time. Perf output
> > contains information only of `void
> > std.concurrency.FiberScheduler.create(void delegate()).wrap()`
> > which took less than 0.5%. But I wouldn't say that I did the
> > profiling ideally so take it with a grain of salt.
>
> Very interesting findings! After making the Fiber fix, I also
> made profiling with valgrind, the result shows MessageBox related
> staff contributes to ~13.7% of total cycles, swapContex related
> staff add up to a larger percentage (My rough estimation is
>  >50%), I'd like to share the result svg but did not figure out
> how to upload here.
>

I have rewrite it to be same as dart version

import std;

void main(string[] args) {
    auto n = args.length > 1 ? args[1].to!int() : 5;

    auto r = new Generator!int(
    {
        for(auto i = 2;;i++)
            yield(i);
    });

    for(auto i=0;i<n;i++)
    {

        auto prime = r.front;
        writeln(prime);
        r = filter(r, prime);

    }

}

Generator!int filter(Generator!int input, int prime)
{

    return new Generator!int(
    {
        while (input.empty is false)
        {
            input.popFront();
            auto i = input.front;
            if (i % prime != 0)
            {
                yield(i);
            }
        }
    });
}
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