Hi, etj

Calling PDL->random is less unique among threads versus rand().

Edit: etj identified a race condition, hence less uniqueness.

use v5.030;
use threads;
use PDL;

BEGIN { $PDL::no_clone_skip_warning = 1; }

for my $id (1..4) {
  threads->create(sub {
    for (1..8000) {
    # my $r = CORE::rand();
      my $r = PDL->random;
      say $r;
    }
  });
}

$_->join for threads->list;

[download]

Thread CORE::rand()

$ perl test.pl | LC_ALL=C sort | uniq -c | sort -n | tail
      1 0.9999196288117
      1 0.999939390107826
      1 1.52499260792638e-05
      1 5.77532994405772e-05
      1 6.39378495463916e-05
      1 6.94432865593342e-05
      1 7.17426768090945e-05
      1 8.48674303988162e-05
      1 9.10499814921195e-05
      1 9.32151475616649e-05

[download]

Thread PDL->random

$ perl test.pl | LC_ALL=C sort | uniq -c | sort -n | tail
      3 0.578372644755136
      3 0.587725272162442
      3 0.629117050685529
      3 0.665209931957569
      3 0.666012741533792
      3 0.715907985301874
      3 0.780440518879262
      3 0.789289520984441
      3 0.859969220981904
      3 0.975280763021946

[download]

In reply to Re^5: PDL and srand puzzle - support added to MCE v1.891 by marioroy
in thread PDL and srand puzzle by syphilis

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