use strict;
use warnings;
use Parallel::ForkManager qw( );
use Time::HiRes qw( time );

my @testLists = qw( sun moon wind air );
my $opts = 'foo';
my $status = 0;

sub regressions {
   my ($opts, $list) = @_;
   print "$$: $list\n";
   sleep 1; # simulate processing
   return 1;
}

my $start = time();
my $pm = Parallel::ForkManager->new( 2 );

# P::FM by default, only waits for its own child processes,
# which is what we want.
# Refer to 'BLOCKING CALLS' in the module documentation.
# Let's decrease the sleep period time (default 1.0).
$pm->set_waitpid_blocking_sleep(0.25);

$pm->run_on_finish(sub {
   my ( $pid, $exit_code, $ident, $exit_signal, $core_dump, $data ) = @_;
   if ( $exit_code || $exit_signal || $core_dump ) {
      # Handle error.
   }
   $status += $data->{ status };
});

for my $list ( @testLists ) {
   $pm->start and next;
   my $status = regressions( $opts, $list );
   $pm->finish( 0, { status => $status } );
}

$pm->wait_all_children();
print "status: $status\n";
printf "duration: %0.3f seconds\n", time() - $start;

__END__
27470: sun
27471: moon
27472: wind
27473: air
status: 4
duration: 2.257 seconds