Measuring memory use of a piece of code at runtime in Java as an on-going functionality of a service

long start = System.nanoTime(); // requires java 1.5
// Segment to monitor
double elapsedTimeInSec = (System.nanoTime() - start) * 1.0e-9;

function profiler($funct) 
{
    $raw_start_time = microtime();
    $funct();
    $raw_end_time = microtime();

    $array_start_time = explode(" ", $raw_start_time);
    $start_time = (int) (1000000 * (double) implode("", [$array_start_time[1], substr($array_start_time[0], 1, 8)]));

    $array_end_time = explode(" ", $raw_end_time);
    $end_time = (int) (1000000 * (double) implode("", [$array_end_time[1], substr($array_end_time[0], 1, 8)]));

    return $end_time - $start_time;
}