Dne 11.5.2017 v 21:30 Laird Nelson napsal(a):
I'm using CDI 2.0 and Weld 3.0.0.CR2 in "SE mode".
If I fire an asynchronous event without any special notification
options, my understanding is that the container will arrange for that
event to be delivered to asynchronous observers.
Is (appropriate) asynchronous observer method invocation guaranteed to
happen at some point? Section 10.2.2 seems to hint that it is:
"Event fired [sic] with the fireAsync() method is [sic] fired
asynchronously. *All the resolved asynchronous observers* (as defined in
Observer resolution) *are called* in one or more different threads."
To me, this says that if I use fireAsync() to fire an event, then if I
have a (resolved) asynchronous observer method for it it will be
notified before the container closes no matter what.
I think it's undefined. And I don't believe it would be reasonable to
block the container shutdown because of an async observer method waiting
for notification. The spec is clear that the container must destroy all
contexts when an application is stopped. And if we destroy the contexts
then the bean declaring the observer or its dependencies might be in
inconsistent state.
(I believe I am observing a race condition somewhere in here that might
show that Weld's default asynchronous event delivery machinery does not
actually get around to delivering the event I've queued up before the
container closes. Sometimes the event is received, sometimes it is
not. Obviously if there is no such guarantee this could be permitted
behavior.)
Best,
Laird
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Martin Kouba
Senior Software Engineer
Red Hat, Czech Republic