Doctrine2: Cannot find concurrently persisted entity with findById - symfony

Question

I have the current setup:
A regular Symfony2 web request can create and persist Job entity which also creates a Gearman Job, lets say this occurs in process 1. The Gearman Job is executed by a Gearman Worker which is passed the Job entity's ID.
I also use Symfony to create a Gearman Worker, this is run as a PHP CLI process, lets call this process 2.
For those not familiar with Gearman the worker code operates something like so:
for loop 5 times
get job from gearman (blocking method call)
get job entity from database
do stuff
Essentially this code keeps a Symfony2 instance running to handle 5 Jobs before the worker dies.
My issue is this: On the first job that the worker handles Doctrine2 is able to retrieve the created job from the database without issue using the following code:
$job = $this->doctrine
->getRepository('AcmeJobBundle:Job')
->findOneById($job->workload()); // workload is the job id
However, once this job completes and the for loop increments to wait for a second job, lets say this arrives from another Symfony2 web request on process 3 creating the Job with ID 2, the call to the Doctrine2 repository returns null even though the entity is definitely in the database.
Restarting the worker solves the issue, so when it carries out it's first loop it can pick up Job 2.
Does anyone know why this happens? Does the first call of getRepository or findOneById do some sort of table caching from MySQL that doesn't allow it to see the subsequently added Job 2?
Does MySQL only show a snapshot of the DB to a given connection as long as it is held open?
I've also tried resetting the entityManager before making the second call to findOneBy to no avail.
Thanks for any advice in advance, this one is really stumping me.
Update:
I've created a single process test case to rule out whether or not it was the concurrency causing the problem, and the test case executes as expected. It seems the only time the repository can't find job 2 is when it is added to the DB on another process.
// Job 1 already exists
$job = $this->doctrine
->getRepository('AcmeJobBundle:Job')
->findOneById(1);
$job->getId(); // this is fine.
$em->persist(new Job()); // creates job 2
$em->flush();
$job = $this->doctrine
->getRepository('AcmeJobBundle:Job')
->findOneById(2);
$job->getId(); // this is fine too, no exception.

Answer 1

Perhaps one process tries to load entity before it has saved by the second process.
Doctrine caches loaded entities by their id, so that when you get a second request for the same object it loads without making another query to the database. You can reed more about Doctrine IdentityMap here