php 程序执行时间和使用内存

require_once('common.php');


 $offset = 0;
 $limit = 500;
$stime=microtime(true);


 while(true) {
echo 'start memory:'.memory_get_usage(), '<br />'; 
$lender_obj = M('Data_LenderModel');
$lender_data = $lender_obj->field('id')->limit($offset,$limit)->select();


$offset += $limit;

if(count($lender_data) <=0 ){
$etime = microtime(true);//获取程序执行结束的时间
$total = $etime-$stime;  //计算差值
echo 'the execute time is '.$total."\n";
exit;
}


foreach ($lender_data as $value) {
echo 'lender_id:', $value['id'], PHP_EOL;
       do_sign_by_lender_id($value['id']);


} 
echo 'end memory:'.memory_get_usage(), '<br />';
 }