scheduledForSynchronization leaks memory when using @ORM\ChangeTrackingPolicy("DEFERRED_EXPLICIT")

[yethee]

Bug Report

scheduledForSynchronization not erases when no changes on the flush.

Q	A
BC Break	yes/no
Version	2.6.3

Summary

I use DEFERRED_EXPLICIT policy for entities in my app. And app crashes with out of memory error during batch processing. Because scheduledForSynchronization keeps references to entities when no changes for commit:

orm/lib/Doctrine/ORM/UnitOfWork.php

Line 359 in 4348209

return; // Nothing to do.

In this case UnitOfWork::postCommitCleanup() not called.

How to reproduce

use Doctrine\ORM\Mapping as ORM;

/**
 * @ORM\Entity()
 * @ORM\ChangeTrackingPolicy("DEFERRED_EXPLICIT")
 */
class Entity
{
}

$entity = $em->find(Entity::class, 123);

$em->persist($entity);
$em->flush();
$em->detach($entity);

var_dump($em->getUnitOfWork()->size()); // int(0)
var_dump($em->getUnitOfWork()->isScheduledForDirtyCheck($entity)); // bool(true)

Was expected that isScheduledForDirtyCheck() return false after commit (flush) in any case.

[Ocramius]

Handled in #7632