When you make a new thread in the method enclosed by @Transactional, transaction does not propagate to the new thread.

For example, in the below case, write1 will rollback but write2 won't.

@Transactional
public void methodA() {
  write1();
  CompletableFuture.runAsync(() -> write2(), Executors.newSingleThreadExecutor());
  if (true) {
    throw new RuntimeException();
  }
}

We need to make clear whether this is the specification or the bug.

Reference: Spring Transaction Management Over Multiple Threads