Responses in-line.
On Mar 7, 2016, at 3:35 PM, Romain Manni-Bucau <rmannibucau(a)gmail.com>
wrote:
2016-03-07 20:53 GMT+01:00 Reza Rahman <reza_rahman(a)lycos.com>:
> Yes, this can be done with a CompletableFuture that has already been
> constructed - just take a look at the API.
>
>
so - just to try to ensure we speak about the same thing:
asyncEvent.fireAsync(...).thenRunAsync(() -> ..., eePool); ?
Correct.
This works but has the drawback to not reuse the observer thread
Why would this matter to the average business code developer? All this
would run from managed executors of some kind or the other anyway...
and keep the original issue: the observer doesn't inherit from the caller
context so it would likely be:
asyncEvent.fireAsync(..., eePool).thenRunAsync(() -> ..., eePool);
Again, why does it matter really? The observer threads themselves should
be running from a managed pool that is smart enough to preserve context
anyway? If the business developer cares about preserving context in their
code, they can use a managed executor themselves on the returned
CompletableFuture.
Cause it is important to state which thread context is there to keep the
integration with other frameworks - think to security ones in particualr -
smooth and doable.
which looks weird since you trigger 2 tasks where you actually want just
one in another thread originally?
I don't follow. Whichever executor service you would use, ultimately there
are at least three different threads associated here in all cases.
asyncEvent.fireAsync(..., eePool).thenRunAsync(() -> ...); // in the fire
async thread
You mean using the same executor? Why does this matter really? They are
all managed executors anyway. At best it's reducing one method parameter.
Cause very few apps are 100% EE in practise, probably never will be and
even if so JavaEE security is not integrated (yet?) at this level.
Are
This last proposal works not that bad if context propagation would work
but since there are cases it would be expected to work and other it
shouldn't - from a user point of view auto inheritance can break thread
safety - I wonder if it shouldn't be spec-ed. Can be the new API I proposed
or even just a new scope close to request scoped but inheritable by design.
> As far as not adding it to CDI, I can see either way. What was the
> original motivation for adding CompletableFutures?
>
> Also, it's a good idea to run this by the platform expert group. I know
> at least JAX-RS is planning to use CompletableFutures for their client API.
>
> On Mar 7, 2016, at 2:39 PM, Romain Manni-Bucau <rmannibucau(a)gmail.com>
> wrote:
>
>
> 2016-03-07 20:35 GMT+01:00 Reza Rahman <reza_rahman(a)lycos.com>:
>
>> Talking with a colleague about this he reminded me of an important fact
>> I almost forgot. The CompletableFuture API can actually be used with custom
>> executors. That means users concerned about managed threads in a Java EE
>> environment can use it with existing EE 7 concurrency executors.
>>
>> Basically this means CompletableFutures are already pretty Java EE ready.
>>
>> If this is the main cited reason for using CompletionStage, is it really
>> that valid of an argument to justify yet another custom subclass specific
>> only to CDI instead of what's likely to be far more familiar and expected?
>>
>>
> Did he mention it is true for *created* comlpetion future which is not
> the case for async events? But this is a good point to not add anything to
> CDI: the feature is a one liner *already*.
>
>
>> On Mar 7, 2016, at 8:11 AM, Reza Rahman <reza_rahman(a)lycos.com> wrote:
>>
>> I think this is a very bad idea. It's better not to use either API and
>> wait to sort out how CompletableFuture can be used in EE consistently.
>> Because of backwards compatibility rules, it is better to have no API than
>> a bad API.
>>
>> On Mar 7, 2016, at 3:45 AM, Romain Manni-Bucau <rmannibucau(a)gmail.com>
>> wrote:
>>
>> 2016-03-07 9:07 GMT+01:00 Martin Kouba <mkouba(a)redhat.com>:
>>
>>>
>>> Dne 7.3.2016 v 09:03 Romain Manni-Bucau napsal(a):
>>>
>>>>
>>>> Le 7 mars 2016 08:35, "Martin Kouba" <mkouba(a)redhat.com
>>>> <mailto:mkouba@redhat.com>> a écrit :
>>>> >
>>>> > Dne 6.3.2016 v 15:39 Romain Manni-Bucau napsal(a):
>>>> >
>>>> >> Hi guys,
>>>> >>
>>>> >> as a user having a ComlpetionStage makes me loose some JDK
>>>> utilities,
>>>> >> can we move back to CompletionFuture?
>>>> >>
>>>> >> It would allow for instance:
>>>> >>
>>>> >> // doesn't work with CompletionStage
>>>> >> CompletionFuture.allOf(event1.fireAsync(...),
>>>> event2.fireAsync(...))
>>>> >> .then(...)
>>>> >
>>>> >
>>>> > Well, this should work if the underlying CompletionStage impl
>>>> supports toCompletableFuture(), i.e. in Weld 3:
>>>> >
>>>>
>>>> Yes but it is not natural to convert it IMO = we can do better
>>>>
>>>> >
CompletableFuture.allOf(event1.fireAsync(...).toCompletableFuture(),
>>>> event2.fireAsync(...).toCompletableFuture())
>>>> >
>>>> > AFAIK the default async execution facility of CompletableFuture is
>>>> ForkJoinPool.commonPool() which is not a good fit for Java EE. Using
>>>> the
>>>> CompletionStage interface allows us to wrap the async calls without the
>>>> specified executor (e.g. CompletionStage.thenApplyAsync(Function<?
>>>> super
>>>> T, ? extends U>)) and supply a default one provided by the impl.
>>>> >
>>>>
>>>> Should use the pool in which the evznt is fired then "then
step" is
>>>> synchronous is my sample so all is decided at fire time
>>>>
>>>
>>> I don't talk about your particular example - I understand that it's
not
>>> using async exec (although the "then()" method does not exist).
>>>
>>>
>> was supposed to represent the different flavours (thenRun, thenCompose,
>> ...) ;).
>>
>> That said I agree on the state switching the pool is better but with
>> these 2 notes:
>>
>> - could be better to hide these poorly designed methods then -> don't
>> use CompletionXXX but a CDI API with a bridge to CompletionX to let the
>> user go back on SE tools
>> - we still don't have a *standard* config for the pool(s) underlying CDI
>> features so it sounds as poor as SE solution IMO (at least a core/max/ttl
>> config in beans.xml)
>>
>>
>>>
>>>> >
>>>> >>
>>>> >> Romain Manni-Bucau
>>>> >> @rmannibucau <
https://twitter.com/rmannibucau> | Blog
>>>> >> <
http://rmannibucau.wordpress.com> | Github
>>>> >> <
https://github.com/rmannibucau> | LinkedIn
>>>> >> <
https://www.linkedin.com/in/rmannibucau> | Tomitriber
>>>> >> <
http://www.tomitribe.com>
>>>> >>
>>>> >>
>>>> >>
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>>>> >>
>>>> >
>>>> > --
>>>> > Martin Kouba
>>>> > Software Engineer
>>>> > Red Hat, Czech Republic
>>>>
>>>>
>>> --
>>> Martin Kouba
>>> Software Engineer
>>> Red Hat, Czech Republic
>>>
>>
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