これでうまくいった

7.php −> 8.php
7.php wait 10seconds
8.php wait 0

7.php

<?php
try {
$oDbCxn = new PDO('sqlite:test1');
$oDbCxn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

}
catch (PDOException $e) {
die("Error connecting to DB");
}
$bUpdatePending = true;
while ($bUpdatePending) {
try {
$oDbCxn->beginTransaction();
$oDbCxn->exec("UPDATE tb1 SET value = value + 1 WHERE id = '1'");
sleep(10);
$oDbCxn->commit();
$bUpdatePending = false; // Exit the loop now the update has been done
}
catch (PDOException $e) {
sleep(3);
$oDbCxn->rollback();
}
}
?>