Assertion error in org.hibernate.engine.internal.BatchFetchQueueHelper

Hi there,

using Hibernate 5.2.16, I’m encountering an assertion error in org.hibernate.engine.internal.BatchFetchQueueHelper#removeNotFoundBatchLoadableEntityKeys

assert idSet.size() == ids.length - results.size();

a) when bytecode enhancement is disabled
b) in Hibernate Search with enabled bytecode enhancement.

Is there a usual suspect I can track down this?
While debugging the assertion, I can see this:


As results show ambigous results, might this be related to an incorrect hashcode/equals implementation?


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From the image, it looks like the results ArrayList have a duplicated User@14158 while the ids are deduplicated.

Try to provide a replicating test case.

Providing a test case will be quite tricky. But I’ve just found out that this only happens when AvailableSettings.DEFAULT_BATCH_FETCH_SIZE is set. Not using batch fetches does not cause this issue.

Without a test case that proves the issue, it’s not clear what exactly is not working properly and requires a fix.

Of course. I will tackle this issue ASAP.

In Hibernate 5.3.0, the error thrown is slightly different as bootstrapping fails.


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Maybe the error message has changed due to working on this issue for improving performance

The difference is now that bootstrapping fails, before the issue occured after the bootstrapping process. But anyhow, a test case exists for this one, so this can be further investigated now.

I’m going to integrate the test case and see if I can fix the issue.

Hi, i have the same problems, at least in one case I could solve it by changing an Fetch.EAGER with implicit JOIN to an Fetch.EAGER with explicit FetchMode.SELECT, which looks like an cartesian product problem to me.

Problem Version: 5.2.17.Final
No Problem before with 5.2.1.Final

I retested Versions, Problems start with 5.2.10.Final, before that I do not have this error.

FetchType.EAGER is almost always a bad idea.

Well OK… but no reason to break existing behaviour.

That’s a bug indeed, but if you stumbled on it, you might have more issues due to using EAGER fetching than the one caused by this regression.

Vlad, thanks for answering, i just wanted to provide some input on the topic.
I will never use EAGER anymore, i swear to the holy god of relationality :wink:

That’s the spirit! Remember that the @ManyToOne and @OneToOne associations are EAGER by default, so keep that in mind.

Using Hibernate 5.3.2, I’m again encountering the original error message when “hibernate.default_batch_fetch_size” is set with bytecode enhanced entities. I will try to provide a test case ASAP.

You should create a new Jira issue for 5.3.2 then. Thanks.

I’m still struggling to create a test case for this due to lack of time, but now has solved the issue.