ClearOnFlush with JPA Gateway returns mixed entity states

[yybmion]

Hi

While reviewing the JPA module code, I noticed something that might be problematic. I wanted to get your thoughts.

What I found:

In DefaultJpaOperations.persistOrMergeIterable(), when using clearOnFlush=true:

// Simplified for clarity
for (Object entity : entities) {
    mergedEntities.add(entityManager.merge(entity));
    
    if (count % flushSize == 0) {
        entityManager.flush();
        if (clearOnFlush) {
            entityManager.clear();  // Previous entities → detached
        }
    }
}
return mergedEntities;  // Mixed state

Potential Issue:
The returned list contains entities in different states:

• Earlier batches: detached (after clear)
• Last batch: managed (before clear)

This could cause problems in downstream handlers:

• Lost changes: Modifications to detached entities won't be persisted
• Unpredictable behavior: Same operation works for some entities but not others

Expectation: Returned entities should be in a consistent state (all managed or all detached), not mixed.

Is this mixed-state behavior intentional, or should the method guarantee consistent entity states in the returned list?

Thanks for your time!

[artembilan]

Do you want to say that our logic in the loop:

if (flushSize > 0 && savedEntities.get() % flushSize == 0) {
	entityManager.flush();
	if (clearOnFlush) {
		entityManager.clear();
	}
}

comes with some flaws that we are missing to flush and clear for the last batch of that iteration?
Feels like we need to perform those one more time after the loop.

Thanks

[yybmion]

You're absolutely right, and thank you for pointing that out!

I just ran a test and you were correct - the final flush/clear in persistOrMerge() already makes all returned entities detached.

I missed that persistOrMerge() already does what you suggested:

private Object persistOrMerge(...) {
    result = persistOrMergeIterable(...);
    
    if (flushSize > 0) {
        entityManager.flush();
        if (clearOnFlush) {
            entityManager.clear();  // ← Already here!
        }
    }
    
    return result;  // All entities are detached at this point
}

So there's no "mixed state" bug - all returned entities are consistently detached.

I apologize for the confusion. I should have traced through the complete call stack before reporting.

Thanks for your patience! 🙏

[artembilan]

Closed as Works as Designed