Question

Exception “org.hibernate.exception.LockAcquisitionException: could not insert” appears sometimes in the following code:

 Question questionClone;
 try {
    questionClone = (Question) question.clone();
 } catch (CloneNotSupportedException e) {
    throw WrappedException.wrap(e);
 }
 questionClone.setCategory(question.getCategory());
 questionClone.setOriginal(false);
 logger.trace("Saving questionClone " + questionClone + " start");
 hibernateSession.save(questionClone);
 logger.trace("Saving questionClone " + questionClone + " end");

when questionClone is saved. Here is the clone method for Question:

public Object clone() throws CloneNotSupportedException {
    Question questionClone = (Question) super.clone();

    questionClone.category = null;

    List<Alternative> alternativesClone = new ArrayList<Alternative>(getInternalAlternatives().size());
    int index = 0;
    for (Iterator<Alternative> iterator = getInternalAlternatives().iterator(); iterator.hasNext();) {
        Alternative alternative = iterator.next();
        Alternative alternativeClone = (Alternative) alternative.clone();
        alternativeClone.setQuestion(questionClone);
        alternativeClone.setIndex(index);
        alternativesClone.add(alternativeClone);
        ++index;
    }
    questionClone.setInternalAlternatives(alternativesClone);

    return questionClone;
}

And clone method for Alternative:

public Object clone() throws CloneNotSupportedException {
    Alternative alternativeClone = (Alternative) super.clone();

    alternativeClone.index = 0;
    alternativeClone.question = null;

    return alternativeClone;
}

Hibernate mapping of question contains this:

<list name="internalAlternatives" inverse="true" cascade="all-delete-orphan">
   <cache usage="read-write"/>
   <key column="QUESTION_ID"/>
   <list-index column="INDEX"/>
   <one-to-many class="Alternative"/>
</list>

Exception states that it cannot insert an Alternative and caused by: com.ibm.db2.jcc.am.SqlTransactionRollbackException: DB2 SQL Error: SQLCODE=-911, SQLSTATE=40001, SQLERRMC=2, DRIVER=4.14.88. As I found out it was a deadlock. Can anyone help with this?

Answer 1

alternativeClone.setQuestion(questionClone); 

and

questionClone.setInternalAlternatives(alternativesClone);

Seems to be the dealock occurs becuase of these lines. You are adding list on internalAlternatives inside your question, and then also setting question inside alternative.