Description:
------------
For what I investigated, it's not related to ext/amqp but it's in librabbitmq; 
well I think, I'm not sure

So my script has a simple publisher, and no consumer (not needed, just fill data 
in a rabbitMQ server). It just publishes to a queue, in Direct mode, with one 
routing key. Easy.

I have a loop feeding some few data (few bytes, each publish() is fed few bytes 
). The loop has 5000 iterations. It may have more, but then I have not enough 
memory and start swaping / OOMing

IMPORTANT :
Using AMQP_IMMEDIATE in publish() triggers the leak.
Not using AMQP_IMMEDIATE in publish() is all right.

For what I noticed using callgrind, massif and memcheck, when using 
AMQP_IMMEDIATE, all the payload is delayed and actually really sent at shutdown, 
allocating lots of buffers for each data and not freeing them immediately, which 
might OOM the machine.
When not using AMQP_IMMEDIATE, the buffers seem to be allocated, sent, then 
freed immediately; thus no memory overhead.

Here are the results :
https://gist.github.com/1846541

The callgrind schemas are actually very interesting, as they clearly show that a 
memory starvation happens when PHP is shutting down using AMQP_IMMEDIATE which 
does not happen when not using AMQP_IMMEDIATE
https://gist.github.com/1846607

Test script:
---------------
class Publisher
{
    protected $channel;
    protected $connection;
    protected $name;
    protected $queue;
    
    public function __construct($exchangeName)
    {
        $this->connection = new \AMQPConnection(array('host'=>'127.0.0.1', 'port'=>5672, 'login'=>'guest', 'password'=>'guest'));
        $this->connection->connect();
        $this->channel = new \AMQPChannel($this->connection);

        $this->exchange = new \AMQPExchange($this->channel);
	$this->exchange->setName($this->name = $exchangeName);
	$this->exchange->setType(AMQP_EX_TYPE_DIRECT);
	$this->exchange->setFlags(AMQP_DURABLE);
	$this->exchange->declare();
	}
    
    public function sendSQLJob($sql)
    {
        $this->exchange->publish($sql, 'sqlkey', AMQP_IMMEDIATE);
    }

}

require __DIR__ . '/config.php';
$i=0;
$j = 5000;
$publisher = new Publisher('sql');
$fp = fopen('some/text/file', 'r');
while($sql = fgets($fp) && --$j) {
    $publisher->sendSQLJob($sql);
    printf("\r%d       \r", $i++);
}
unset($publisher);

Expected result:
----------------
memory level normal

Actual result:
--------------
memory consumption very high but not a leak as all buffers get freed, they simply 
seem to stack in a loop thus blowing up the memory