Why is php script slowing down?

Question

I was working on migration scripts which selects data from one MySQL database and import through doctrine into another MySQL database. The problem was that after every chunk of created entities, my scripts slowed down.

first 100 articles takes about 5 seconds to import, next 100 articles takes 7 seconds, next 10 seconds and so on. It is really big problem, because I need to import about 1.500.000 articles.

Answer 1

I found out that php >=5.3 has garbage collector cleaner. So, when I import chunk of articles I call gc_collect_cycles(); to clear memory out of all entities which script will needs no more. The script is slowing down no more!

If you are using a framework, check if it has its own cache system. If you are using doctrine turn off SQL logger

/** @var $em EntityManager */
$em = $this->getContainer()->get('doctrine')->getEntityManager();
$em->getConnection()->getConfiguration()->setSQLLogger(null);

and then clear doctrine cache after every chunk is imported

$em->clear();