## either load the saved random seed and state data from the
## serialization (resume a paused compuatation), or start with 
## new state data and the given random seed (start new 
## compuation)
my ($foo, $bar, $random_seed) = deserialize('saved')
                             || initial_values();

while (1) {
    srand($random_seed);

    ## some crunching on $foo, $bar, using lots of rand()

    ## decide what the next iteration's seed will be
    $random_seed = int rand( 2 << 31 );
    
    if (check_for_user_interrupt()) {
        ## save state, along with the seed for next iteration
        serialize('saved', $foo, $bar, $random_seed);
        exit;
    }
}