PDOProxy, memory isn't freed after query about swoole-src HOT 2 OPEN

Because a connection pool is used, the connections inside the pool will only be released when the program terminates.

from swoole-src.

Actually, this is how mysqlnd operates.
Let's take the following example :

<?php
var_dump(memory_get_usage(true) / 1024 / 1024);

$pdoClient = new \PDO($dsn, $user, $password, $options);
$pdoClient->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, false); // doesn't matter anyway
$prepare = $pdoClient->prepare('select * from some_table'); // 400k entries
$prepare->execute();
$results = $prepare->fetchAll(\PDO::FETCH_ASSOC);

$prepare->closeCursor(); // doesn't matter anyway

var_dump(count($results));

unset($results, $prepare, $pdoClient);

var_dump(memory_get_usage(true) / 1024 / 1024);

Will print

int(2)
int(400000)
int(366)

In a php stateless app, that ok, we will retrieve our 366mb of memory at the end of the http request.
In a php stateful app, I don't manage to retrieve it.
Maybe the gc will do it's job sometimes but I doubt it.

I guess the only solution is to do the query outside the "Constant::EVENT_REQUEST" and say goodbye to my 366mb of memory... (it's better than saying goodbye to 366*number of workers though)

I didn't manage to find a solution yet to free this.
So indeed, it's not really linked to Swoole internals.

from swoole-src.