test 1/001
  callback 1 commit
  callback 1 rollback
  callback 1 rollback
  unregister callback 1
  unregister callback 1
  callback 2 commit
test 1/002
  unregister callback 2
  callback 1 commit
  callback 3 commit
  unregister callback 2
  callback 1 commit
  callback 4 commit
  callback 3 commit
test 1/003
  callback 1 commit
  callback 2 commit
test 2/001
  callback 1 commit
  callback 1 rollback
  callback 1 rollback
  unregister callback 1
  unregister callback 1
  callback 2 commit
test 2/002
  unregister callback 2
  callback 1 commit
  callback 3 commit
  unregister callback 2
  callback 1 commit
  callback 4 commit
  callback 3 commit
test 2/003
  callback 1 commit
  callback 2 commit