• mw (12/12) Dec 07 2020 https://dlang.org/phobos/std_parallelism.html#.parallel
• Dukc (6/11) Dec 07 2020 Allocate a `shared int` before the foreach loop. In the loop
• =?UTF-8?Q?Ali_=c3=87ehreli?= (15/29) Dec 07 2020 s=20

mw <mingwu gmail.com> writes:

https://dlang.org/phobos/std_parallelism.html#.parallel

auto logs = new double[1_000_000];

foreach (i, ref elem; parallel(logs))
{
     elem = log(i + 1.0);
}


In Python, using joblib, I can use `verbose` level like this:

r = Parallel(n_jobs=2, verbose=10)(delayed(sleep)(.2) for _ in 
range(10))

to print out the progress.

How to do this in D's parallel loop?

thanks.

Dukc <ajieskola gmail.com> writes:

On Monday, 7 December 2020 at 08:16:50 UTC, mw wrote:
 r = Parallel(n_jobs=2, verbose=10)(delayed(sleep)(.2) for _ in 
 range(10))

 to print out the progress.

 How to do this in D's parallel loop?

 thanks.

Allocate a `shared int` before the foreach loop. In the loop 
when, let's say `!(i & 0xFFF)`,  atomically increment the shared 
variable and print it's number.

Disclaimer: no experience about using `shared`, but this is what 
I'd try.

=?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:

On 12/7/20 4:48 AM, Dukc wrote:
 On Monday, 7 December 2020 at 08:16:50 UTC, mw wrote:
 r =3D Parallel(n_jobs=3D2, verbose=3D10)(delayed(sleep)(.2) for _ in r=


ange(10))
 to print out the progress.

 How to do this in D's parallel loop?

 thanks.

=20
 Allocate a `shared int` before the foreach loop. In the loop when, let'=

s=20
 say `!(i & 0xFFF)`,=C2=A0 atomically increment the shared variable and =

print=20
 it's number.
=20
 Disclaimer: no experience about using `shared`, but this is what I'd tr=

y.

Yes, that would be the way but I don't know the effect of using shared=20
or not. But because the progress needs to be somehow reported, an atomic =

variable may not be sufficient (unless a separate thread is reading it,=20
etc.)

This issue came up during one of my recent presentations at this point:

   https://www.youtube.com/watch?v=3DdRORNQIB2wA&feature=3Dyoutu.be&t=3D1=
527

I used a synchronized block in that code because it did not affect=20
performance in my use case.

Ali