关于一个 Laravel 使用 cursor 占用内存问题

    public function handle()
    {
        EloquentStoredEvent::query()->cursor()->each(function (EloquentStoredEvent $storedEvent){
            // 逻辑处理
            $this->info(round(memory_get_usage()/1024/1024, 2).'MB');
        });
    }Copy

$this->info(round(memory_get_usage()/1024/1024, 2).'MB');Copy

<?php

ini_set('memory_limit', '3024M');

class Db{
    public $dbh;

    public function __construct()
    {
        $this->dbh = new PDO('mysql:host=127.0.0.1;port=3306;dbname=test', 'root', '',
            [
                PDO::ATTR_CASE => PDO::CASE_NATURAL,
                PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
                PDO::ATTR_ORACLE_NULLS => PDO::NULL_NATURAL,
                PDO::ATTR_STRINGIFY_FETCHES => false,
                PDO::ATTR_EMULATE_PREPARES => true,
            ]);

    }

    public function fetch()
    {
        $sth = $this->dbh->prepare("select * from `stored_events`");

        $sth->setFetchMode(PDO::FETCH_OBJ);
        $sth->execute();

        while ($record = $sth->fetch()) {
            yield $record;
        }
    }
}

$db = new Db();
var_dump(round(memory_get_usage()/1024/1024, 2).'MB');

foreach ($db->fetch() as $v) {
    var_dump(round(memory_get_usage()/1024/1024, 2).'MB');
};
var_dump(round(memory_get_usage()/1024/1024, 2).'MB');Copy