use Parallel::ForkManager qw( );
 
my @testLists = ...;

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

for my $list ( @testLists ) {
   $pm->start and next;

   $status += regressions( $opts, $list );

   $pm->finish;
}

$pm->wait_all_children();

##</code><code>##

use Parallel::ForkManager qw( );
 
my @testLists = ...;
my $status = 0;

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

$pm->run_on_finish(sub {
   my ( $pid, $exit_code, $ident ) = @_;
   $status += $exit_code;
});
 
for my $list ( @testLists ) {
   $pm->start and next;

   my $status = regressions( $opts, $list );
   $status = 255 if $status > 255;
   
   $pm->finish( $status );
}

$pm->wait_all_children();

##</code><code>##

use Parallel::ForkManager qw( );
 
my @testLists = ...;
my $status = 0;

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

$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();