From @AlexDaniel

Let's try running the same code twice​:

<AlexDaniel> m​: my @​x = ^10; my @​y = @​x.hyper(​:3batch, :5degree).map​: {
sleep rand / 100000; $_ + 1 }; say @​y
<camelia> rakudo-moar a5fe34​: OUTPUT«[]â�¤Â»
<AlexDaniel> m​: my @​x = ^10; my @​y = @​x.hyper(​:3batch, :5degree).map​: {
sleep rand / 100000; $_ + 1 }; say @​y
<camelia> rakudo-moar a5fe34​: OUTPUT«[1 2 3 4 5 6 7 8 9 10]â�¤Â»

The thing is that sometimes ï½¢hyperï½£ decides to return an empty list. This
is a real problem because it basically renders it useless (too unreliable).

If you have problems reproducing it, try changing ï½¢/ 100000ï½£ to something
else. This delay is not really relevant but it seems like it affects the
chances to get one result or another.

Here's also a golfed down version​:

Code​:
dd @​(^10 .hyper(​:1batch).map​: { sleep rand; $_ })

Result​:
()
OR
(0, 1, 2, 3, 4, 5, 6, 7, 8, 9)

According to the execution time ï½¢hyperï½£ does not even bother to compute the
result in these problematic cases (it just returns an empty list without
trying to process the data). That being said, there is a chance that it
fails half way through, see next example.

Another interesting issue (probably the same one)​:

Code​:
.say for (^10).hyper(​:1batch).map​: { sleep rand; $_ }

Result​:
1
OR
2
OR
3
OR
0
3
2
1
5
8
7
4
6
9
OR etc.

So not only it is out of order (#​127099), but it is also extremely broken.

It looks like there is no such problem with ï½¢raceï½£.

IRC log (nothing useful there though)​:
http://irclog.perlgeek.de/perl6/2016-02-02#i_11975794

From liukan@360.cn

the following code produces () on random occasions.

while 1 {
my @​a = 1, 3, 2, 9, 0, |( 1 .. 100 );
my $a = @​a.hyper.map​: * + 1;
$a.list.say;
}

(2 4 3 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 ...)
(2 4 3 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 ...)
(2 4 3 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 ...)
(2 4 3 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 ...)
(2 4 3 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 ...)
()
(2 4 3 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 ...)
(2 4 3 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 ...)
(2 4 3 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 ...)
(2 4 3 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 ...)
(2 4 3 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 ...)
(2 4 3 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 ...)
(2 4 3 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 ...)
(2 4 3 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 ...)
(2 4 3 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 ...)
()
(2 4 3 10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 ...)

liukan@​candor​:~/Code$ perl6 -v
This is Rakudo version 2016.07.1 built on MoarVM version 2016.07
implementing Perl 6.c.
liukan@​candor​:~/Code$ uname -a
Linux candor 4.4.0-34-generic #​53-Ubuntu SMP Wed Jul 27 16​:06​:39 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

- kan

From @smls

Can still confirm on [Rakudo version 2016.08.1-116-gf648d3b built on MoarVM version 2016.08-32-ge52414d].

Seems related to tickets 126597 and 128084, except that those are about cases where hyper *reliably* returns an empty sequence instead of the correct result.

The RT System itself - Status changed from 'new' to 'open'

From darkfeathers9@gmail.com

perl6 --version​:
This is Rakudo version 2016.12 built on MoarVM version 2016.12

OS​: Arch Linux using GCC compiler and MoarVM

Using .hyper on an array sometimes returns a result and most of the
times it does not. Additionally using .hyper may cause the entire
process to sleep and no output returns.

Code​:

use experimental :pack;

my $file = slurp("pic.png", :bin);
my $start = 8;
my $end = 11;
my $len = 0;
my $header = "";

my $data = "";
while $end <= $file.bytes {
  $len = :16(Blob.new($file[$start..$end]).unpack("H*")) ;
  $header = Blob.new($file[$start+4..$end+4]).unpack("H*");

  #!!!!!!!!!!!!!!!!!Problem is here!!!!!!!!!!!!!!!!!
  $data = $file[$start+8 ..$start+8+$len].hyper.map({$_
.fmt('%02x')}).list;

  say $data;
  $start = $start + $len + 12 ;
  $end = $start + 3;
}

expected output (Omitting .hyper and using only first 3 lines of
output)​:
(00 00 01 85 00 00 02 6c 08 06 00 00 00 12)
(08 08 08 08 7c)
(53 6f 66 74 77 61 72 65 00 67 6e 6f 6d 65 2d 73 63 72 65 65 6e 73 68
6f 74 ef)

actual output​:
()
()
()
*process sleeps here*

From @jnthn

On Mon, 01 Feb 2016 21​:59​:33 -0800, alex.jakimenko@​gmail.com wrote​:

Let's try running the same code twice​:

<AlexDaniel> m​: my @​x = ^10; my @​y = @​x.hyper(​:3batch, :5degree).map​: {
sleep rand / 100000; $_ + 1 }; say @​y
<camelia> rakudo-moar a5fe34​: OUTPUT«[]â�¤Â»
<AlexDaniel> m​: my @​x = ^10; my @​y = @​x.hyper(​:3batch, :5degree).map​: {
sleep rand / 100000; $_ + 1 }; say @​y
<camelia> rakudo-moar a5fe34​: OUTPUT«[1 2 3 4 5 6 7 8 9 10]â�¤Â»

The thing is that sometimes ï½¢hyperï½£ decides to return an empty list. This
is a real problem because it basically renders it useless (too unreliable).

If you have problems reproducing it, try changing ï½¢/ 100000ï½£ to something
else. This delay is not really relevant but it seems like it affects the
chances to get one result or another.

Here's also a golfed down version​:

Code​:
dd @​(^10 .hyper(​:1batch).map​: { sleep rand; $_ })

Result​:
()
OR
(0, 1, 2, 3, 4, 5, 6, 7, 8, 9)

According to the execution time ï½¢hyperï½£ does not even bother to compute the
result in these problematic cases (it just returns an empty list without
trying to process the data). That being said, there is a chance that it
fails half way through, see next example.

Another interesting issue (probably the same one)​:

Code​:
.say for (^10).hyper(​:1batch).map​: { sleep rand; $_ }

Result​:
1
OR
2
OR
3
OR
0
3
2
1
5
8
7
4
6
9
OR etc.

So not only it is out of order (#​127099), but it is also extremely broken.

It looks like there is no such problem with ï½¢raceï½£.

IRC log (nothing useful there though)​:
http://irclog.perlgeek.de/perl6/2016-02-02#i_11975794

Fixed in new hyper/race implementation; tests in S07-hyperrace/hyper.t and S07-hyperrace/race.t (for original post and other examples that I found in the discussion of this ticket).

@jnthn - Status changed from 'open' to 'resolved'