use threads;
use threads::shared;
use DBI;

my $dbh = DBI->connect( );

## Do stuff

my $done :shared = 0;

async {
	$dbh->ping while !$done and sleep 300; ## Adjust frequency to suit
}->detach;

## system 'yourLongRunningCmd';

$done = 1; sleep 1; ## Thread disappears

## The rest of your script