PHP循环中允许的内存大小耗尽

I have the following code:

 15 $users = pg_fetch_all($result);
 16 $chart_data = array();
 17 foreach ($users as $value)
 18 {
 19         //var_dump($value);
 20         $temp = array();
 21         $temp['label'] = $value['id'];
 22         $temp['y'] = $value['sum'];
 23 print_r($temp);
 24 /*
 25 echo "<pre>";
 26         var_dump($temp);
 27 echo "</pre>";
 28 */      
 29         array_push($chart_data,$temp);
 30 }
 31 echo count($chart_data);

When I run my code, I get the following error message:

[Thu Apr 28 17:23:39.278844 2016] [:error] [pid 24321] [client 10.63.8.104:58362] PHP Fatal error:  Allowed memory size of 134217728 bytes exhausted (tried to allocate 20480 bytes) in /var/www/localhost/htdocs/audit/index.php on line 21

This is a sample of the output I get from the print_r():

Array ( [label] => 12 [y] => 0.0021 ) 

I can't see how line 21 is problematic here. Maybe I need to explicitly reset temp to an empty array?? Not sure too but any suggestions welcome. Thanks.