As your output shows, the same process is handling all the tasks. That's because the parent is forking a child but then continuing the work itself.

You are missing the statement that causes the parent to skip out of the loop. See the doc for Parallel::ForkManager, which states (emphasis added):

The following example shows the difference: 

use strict; use warnings; use feature 'say';
use Parallel::ForkManager;
use Time::HiRes qw/ time /;

$|++;

my $forker = Parallel::ForkManager->new(4);
say "v.1";
for ( 0 .. 9 ) {
    my $pid = $forker->start;
    if ( $pid ) {
        say "1 $$ $_ start: " . time;
        sleep 1;
    }
    $forker->finish;
}

my $forker2 = Parallel::ForkManager->new(4);
say "v.2";
for ( 0 .. 9 ) {
    my $pid = $forker->start and next;
    say "2 $$ $_ start: " . time;
    sleep 1;
    $forker->finish;
}

__END__

[download]
Output: 
$ perl 1187274.pl

v.1
1 19015 0 start: 1491486225.44169
1 19015 1 start: 1491486226.44244
1 19015 2 start: 1491486227.44318
1 19015 3 start: 1491486228.44402
1 19015 4 start: 1491486229.44495
1 19015 5 start: 1491486230.44586
1 19015 6 start: 1491486231.447
1 19015 7 start: 1491486232.44791
1 19015 8 start: 1491486233.44877
1 19015 9 start: 1491486234.4497
v.2
2 19026 0 start: 1491486235.45079
2 19027 1 start: 1491486235.45113
2 19028 2 start: 1491486235.45138
2 19029 3 start: 1491486235.4517
2 19030 4 start: 1491486237.45457
2 19031 5 start: 1491486237.45492
2 19032 6 start: 1491486237.45516
2 19033 7 start: 1491486237.45543
2 19035 9 start: 1491486239.45953
2 19034 8 start: 1491486239.45992

[download]

Hope this helps!


The way forward always starts with a minimal test.

In reply to Re^3: Parallel::Forkmanager question by 1nickt
in thread Parallel::Forkmanager question by jamesgerard1964

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