Spring transaction: unexpected rollback behavior - spring

Question

I am doing a simple experiment for debugging purpose.
First I insert serveral records to database, and then I do a invalid data conversion which will throw DataIntegrityViolationException, but I will catch the exception.
I expected the records being successfully inserted into the db, since I catch the checked exception. But the whole thing is rolled back.
I do the experiment again using TransactionTemplate instead of using annotation, same result.
My questions are:
is this the expected behavior?
If anwser to No.1 is yes, then I catch the exception, how is it possible that spring knows an exception is thrown?
Here is my code:
public void insertValue() {
jdbcTemplate.execute("insert into people (person_id, name) values (4, 'asjkdhadsjkqhweqkewhkashdkahd')");
jdbcTemplate.execute("insert into people (person_id, name) values (5, 'tttqqq')");
}
// this should throw exception
public void truncateValue() {
jdbcTemplate.execute("alter table people alter column name varchar(7)");
}
public void jdbc_calls() {
insertValue();
try {
truncateValue();
} catch (Exception e) {
System.out.println(e.getMessage());
}
System.out.println("Finish");
}
public void run() {
TransactionTemplate transactionTemplate = new TransactionTemplate(transactionManager);
transactionTemplate.setPropagationBehavior(TransactionDefinition.PROPAGATION_REQUIRED);
transactionTemplate.setIsolationLevel(TransactionDefinition.ISOLATION_DEFAULT);
transactionTemplate.execute(transactionStatus -> {
try {
jdbc_calls();
} catch (RuntimeException e) {
throw e;
} catch (Throwable e) {
throw new RuntimeException(e);
}
return null;
});
}
More about question No.2.
Here is the source code of TransactionTemplate.execute()
From my understanding, if I don't throw an exception, rollbackOnException won'r be triggered.
public <T> T execute(TransactionCallback<T> action) throws TransactionException {
Assert.state(this.transactionManager != null, "No PlatformTransactionManager set");
if (this.transactionManager instanceof CallbackPreferringPlatformTransactionManager) {
return ((CallbackPreferringPlatformTransactionManager) this.transactionManager).execute(this, action);
}
else {
TransactionStatus status = this.transactionManager.getTransaction(this);
T result;
try {
result = action.doInTransaction(status);
}
catch (RuntimeException | Error ex) {
// Transactional code threw application exception -> rollback
rollbackOnException(status, ex);
throw ex;
}
catch (Throwable ex) {
// Transactional code threw unexpected exception -> rollback
rollbackOnException(status, ex);
throw new UndeclaredThrowableException(ex, "TransactionCallback threw undeclared checked exception");
}
this.transactionManager.commit(status);
return result;
}
}

Answer 1

is this the expected behavior?
Yes, it is.
If anwser to No.1 is yes, then I catch the exception, how is it possible that spring knows an exception is thrown?
When an exception occurs, spring will mark your transaction as rollbackOnly.
So even when you catch your exception, at the end of your method, your transaction still rolled back.
In your case, I don't get why you use #Transaction since you want to commit regardless if exception occurs.
Edit
When you're using transaction with DB, the transaction invocation is delegated to EntityManager.
Look at AbstractEntityManagerImpl#handlePersistenceException:
#Override
public void handlePersistenceException(PersistenceException e) {
if ( e instanceof NoResultException ) {
return;
}
if ( e instanceof NonUniqueResultException ) {
return;
}
if ( e instanceof LockTimeoutException ) {
return;
}
if ( e instanceof QueryTimeoutException ) {
return;
}
try {
markForRollbackOnly();
}
catch ( Exception ne ) {
//we do not want the subsequent exception to swallow the original one
LOG.unableToMarkForRollbackOnPersistenceException(ne);
}
}
When exception occurs, the EntityManager mark your transaction as rollbackOnly before throws out the exception for you to catch.
After the exception is catched in your service, the AbstractPlatformTransactionManager will try to commit (because, as you know, no exception is detected there), but the EntityManager refuses to commit because its detect that the transaction marked as rollback-only.
If you read the exception, you will see something like:
javax.persistence.RollbackException: Transaction marked as rollbackOnly