<?php
function doQuery($db) {
    try {
        $sql = 'select * from db limit 1';
        $result = $db->query($sql);
        echo "records returned: " . count($result) . PHP_EOL;
    } catch (Exception $e) {
        echo $e->getMessage() . PHP_EOL;
        echo $e->getTraceAsString() . PHP_EOL;
    }
}
function getDatabase() {
    return new PDO('mysql:host=localhost;dbname=mysql', 'user', 'pass', Array(
        PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
    ));
}
echo "before fork" . PHP_EOL;
// this is an idle database connection that belongs to the parent and is not used by the child and should survive the fork
$idledb = getDatabase();
doQuery($idledb);
$db = getDataBase();
$pid = pcntl_fork();
if ($pid == -1) {
    die('could not fork');
} elseif ($pid) {
    // sleep for 1 sec, time for the child query
    sleep(1);
    echo "parent" . PHP_EOL;
    // this reconnect should not be necessary, but otherwise doQuery() will fail
    $db = getDatabase();
    doQuery($db);
} else {
    echo "child" . PHP_EOL;
    // this should initiate a new connection object, independant of the parent one
    $db = getDatabase();
    doQuery($db);
    exit();
}
echo "after fork" . PHP_EOL;
// this one fails since the database connection has been closed by the child's exit
doQuery($idledb);
echo "end" . PHP_EOL;