php/symfony/doctrine 内存泄漏?

My model has a certain kind of object called "Sector", each of which has several objects of type "Cupo" (usually ranging from 50 up to 200000). These objects are pretty small; just a short identifier string and one or two integers. Whenever a group of Sectors are created by the user, I need to automatically add all these instances of "Cupo" to the database. In case anything goes wrong, I'm using a doctrine transaction to roll back everything. The problem is that I can only create around 2000 instances before php runs out of memory. It currently has a 128MB limit, which should be more than enough for handling objects that use less than 100 bytes. I've tried increasing the memory limit up to 512MB, but php still crashes and that doesn't solve the problem. Am I doing the batch insertion correctly or is there a better way?

错误如下:

Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 71 bytes) in /Users/yo/Sites/grifoo/lib/vendor/symfony/lib/log/sfVarLogger.class.php on line 170

这是代码:

public function save($conn=null){

    $conn=$conn?$conn:Doctrine_Manager::connection();

    $conn->beginTransaction();


    try {
        $evento=$this->object;


        foreach($evento->getSectores() as $s){

            for($j=0;$j<$s->getCapacity();$j++){

                $cupo=new Cupo();
                $cupo->setActivo($s->getActivo());
                $cupo->setEventoId($s->getEventoId());
                $cupo->setNombre($j);
                $cupo->setSector($s);

                $cupo->save();

            }
        }

        $conn->commit();
        return;
    }
    catch (Exception $e) {
        $conn->rollback();
        throw $e;
    }

再一次，此代码对于少于 1000 个对象可以正常工作，但任何大于 1500 的对象都会失败.感谢您的帮助.

$cupo->save();
$cupo->free();
$cupo = null;

all:
  doctrine:
    class: sfDoctrineDatabase
    param:
      dsn: 'mysql:host=localhost;dbname=.......'
      username: .....
      password: .....
      profiler: false

Doctrine_Manager::connection()->setAttribute(Doctrine_Core::ATTR_AUTO_FREE_QUERY_OBJECTS, true ); 

$cupo = null;

unset($cupo);