Atomic

TransactionManagementError

• Codes

  @transaction.atomic
  def foo():
      while:
          # Queries
  

• Error

  django.db.transaction.TransactionManagementError: An error occurred in the current transaction. You can't execute queries until the end of the 'atomic' block.
  

• Reasons

  • while makes atomic not end

• Solutions

  def foo():
      while:
          with transaction.atomic():
              # Queries
  

IntegrityError

• Codes

  with transaction.atomic():
      try:
          profile = Profile.objects.select_for_update().get(uid=uid)
      except Profile.DoesNotExist:
          pass
  
  profile.foo = 'bar'
  profile.save()
  

• Error

  django.db.utils.IntegrityError: (1062, "Duplicate entry 'xxx' for key 'ooo'")
  

• Reasons

  • TOFOUND

• Solutions

OperationalError

• Codes

  with transaction.atomic():
      try:
          profile = Profile.objects.select_for_update().get(uid=uid)
      except Profile.DoesNotExist:
          pass
  

• Error

  django.db.utils.OperationalError: (1213, 'Deadlock found when trying to get lock; try restarting transaction')
  

• Reasons

  • innodb_lock_wait_timeout

    • Terminal1

      with transaction.atomic():
          profile = Profile.objects.select_for_update().get(uid=uid)
          time.sleep(10)
      

    • Terminal2

      with transaction.atomic():
          profile = Profile.objects.select_for_update().get(uid=uid)  # Wait
      

  • TOFOUND

• Solutions

  from django.db.utils import OperationalError
  
  with transaction.atomic():
      try:
          profile = Profile.objects.select_for_update().get(uid=uid)
      except Profile.DoesNotExist:
          pass
      except OperationalError:
          # TODO
  

Override

• Codes

  • Terminal1

    with transaction.atomic():
        profile = Profile.objects.get(uid=uid)
        profile.diamond = 10
        time.sleep(10)
        profile.save()
    

  • Terminal2

    with transaction.atomic():
        profile = Profile.objects.select_for_update().get(uid=uid)  # Not Wait
        profile.diamond = 100
        profile.save()
    

  • Diamond

    Profile.objects.get(uid=uid).diamond  # 10, not 100
    

• Solutions

  • Only get profile by Profile.objects.select_for_update().get(uid=uid) if profile.save()