#!/usr/bin/perl

use Parallel::ForkManager;

my $max_threads = 5;    # Chose a number for best performace.

my $fork_mgr = new Parallel::ForkManager($max_threads);

my @big_list =
(
    {
        query   =>  'SELECT foo FROM tblBar WHERE baz LIKE `%frob%`',
        started =>  0,
        complete=>  0,
        exit_code=> undef,
        results =>  [],
    },
    
    # etc
);

$fork_mgr->run_on_finish
(
    sub
    {
        my($child_pid, $exit_code, $child_id, $exit_signal, $core_dump, $ret_data) = @_;
        # Code to store the results from each thread go here.
        
        # eg:
        $big_list[$child_id]{exit_code} = $exit_signal;
        $big_list[$child_id]{complete}  = 1;
        $big_list[$child_id]{results}   = $ret_data;
    }
);

for( my $itemNum=0; $itemNum<scalar @big_list; $itemNum++ )
{
    $fork_mgr->start($itemNum) and next URL
    
    # Code in this block will run in parallel
    my $thisQuery = $big_list[$itemNum];
    
    my $result = do_query($thisQuery{query});
    
    if( $result->ran_OK() )
    {
        $thisQuery{results} = $result->get_results();
    }
    
    # Store the final result. The value you pass to finish,
    # and the data structure reference will be
    # received by the sub you defined in run_on_finish
    $fork_mgr->finish( $result->ran_OK(), $thisQuery{results} );
}

$fork_mgr->wait_all_children();

# Now all child threads have finished,
# your results should be available.