NH-3880 - HiLo optimizer for enhanced TableGenerator not Generating next value correctly when called from different processes

[nhibernate-bot]

Tomas Gerhardsen created an issue — 10th June 2016, 5:48:01:

The hilo optimizer is not calculating the correct id when called from two different processes.

You will get Primary key Violations if you use the enhanced tablegenerator with hilo and two different processes sharing the same db.

Once the optimizer reaches the upper limit of a bucket it should get a new one from db and use it to calculate the new bucket. This does not happen.

The code:

else if (_upperLimit <= _value)
{
	_lastSourceValue = callback.GetNextValue();
	_upperLimit = (_lastSourceValue * IncrementSize) + 1;
}
return Make(_value++); //<--- New _upperLimit not used. We will get duplicate identities If another process called this

Should be something like:

else if (_upperLimit <= _value)
{
	_lastSourceValue = callback.GetNextValue();
	_upperLimit = (_lastSourceValue * IncrementSize) + 1;
	_value = _upperLimit - IncrementSize;
}
return Make(_value++);

---

Oskar Berggren added a comment — 10th June 2016, 8:46:48:

Strange... Could you dig up a reference to the corresponding code in Hibernate please?

---

Tomas Gerhardsen added a comment — 10th June 2016, 10:58:56:

The bug is found in Hibernate also: https://hibernate.atlassian.net/browse/HHH-3628

It is not fixed yet in the main branch: https://github.com/hibernate/hibernate-orm/blob/master/hibernate-core/src/main/java/org/hibernate/id/enhanced/HiLoOptimizer.java#L80

[hazzik]

Fixed in Hibernate here:

1. https://github.com/hibernate/hibernate-orm/commit/daa48b7db9bc8533a574d92fc2d6ea6fc6816702
2. https://github.com/hibernate/hibernate-orm/commit/1aed1b50f7ecfa4129d47ddeb45a10207c2fd149

[ZmorzynskiK]

Hi,

I just stumbled upon this issue. I'm using the latest NHibernate (5.4.6) and got this violation when using HiLo optimizer. I'm wondering what's the suggested way of dealing with it? Should I just change to other optimizer like "pooled"? It looks like "pooled" updates _value before returning.