The following uses threads for comparison. Locking is required to not garble output, handled automatically i.e. MCE->say, MCE->print, MCE->printf. Here, a count below 32 million indicates duplicate lines in the output.

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

use v5.030;
use threads;
use threads::shared;
use PDL;

BEGIN { $PDL::no_clone_skip_warning = 1; }

my $lock : shared = 0;

for my $tid (1..64) {
    threads->create(sub {
        my $output = "";
        for (1..500000) {
          # my $r = CORE::rand();
            my $r = PDL->random;
            $output .= "$r\n";
        }
        lock $lock;
        print $output;
    });
}

$_->join for threads->list;

[download]

CORE::rand()

$ perl test6.pl | LC_ALL=C sort -u | wc -l
32000000

$ perl test6.pl | LC_ALL=C sort -u | wc -l
32000000

$ perl test6.pl | LC_ALL=C sort -u | wc -l
32000000

[download]

PDL->random

$ perl test6.pl | LC_ALL=C sort -u | wc -l
25105304

$ perl test6.pl | LC_ALL=C sort -u | wc -l
25304231

$ perl test6.pl | LC_ALL=C sort -u | wc -l
25290392

[download]

Improving sort

Mentioned in my prior post, the parallel mcesort program with integrated mini-MCE resides in a GitHub Gist. Copy the script to /usr/local/bin and sudo chmod +x /usr/local/bin/mcesort or bin path of your choice.

perl test6.pl | LC_ALL=C mcesort -j6 -u | wc -l

[download]

In reply to Re^9: PDL and srand puzzle - testing using threads by marioroy
in thread PDL and srand puzzle by syphilis

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