[cdi-dev] Async events. We need ideas to improve CDI-499

Mark Struberg struberg at yahoo.de
Tue Feb 10 04:42:44 EST 2015

No they are not async in the sense that they get executed in a parallel thread. That simply won't work. Think about TransactionPhase.BEFORE_COMPLETION.
There is a huge difference between 'it will get called on the same thread but I have no control _when_' and 'it will get called on a totally new thread'-

For the TransactionPhase it is the first case imo.


> On Tuesday, 10 February 2015, 10:30, Jozef Hartinger <jharting at redhat.com> wrote:
> >T ransactional observers are by definition async so they should behave 
> the same no matter if fired with fire() or fireAsync().
> On 02/10/2015 09:13 AM, Mark Struberg wrote:
>>  Oh one more thing I found which is most probably broken or totally changes 
> the behaviour
>>  8.) All observers with transactionPhase != IN_PROGRESS
>>  LieGrue,
>>  strub
>>>  On Tuesday, 10 February 2015, 8:58, Mark Struberg 
> <struberg at yahoo.de> wrote:
>>>>  Hi José!
>>>  Backward compatibility is perfectly fine with both approaches. People 
> can use
>>>  BeanManager#fire() instead of the newly proposed 
> BeanManager#fireAsync().
>>>  My point is that many people will simply not be able to use fireAsync() 
> because
>>>  as a framework developer you really need to code defensive. Without an 
> explicit
>>>  opt-in on observer side fireAsync() can basically only be used in 
> situations
>>>  where you _exactly_ know all your observers...
>>>  An No @Async annotation would also be nice as it could not only be 
> used at
>>>  @Observes but also for @Event
>>>  @Inject
>>>  @Async
>>>  @Event
>>>  private Event<UserLoggedIn> userLoggedInEventSource;
>>>  The benefit of an own @Async annotation over extending e.g. the @Event
>>>  annotation is that it would be perfectly backward compatible. This code 
> would
>>>  also run on CDI-1.0 .. 1.2 containers (as all annotations which are not
>>>  available on the classpath will simply be ignored by the JVM.
>>>  LieGrue,
>>>  strub
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