[cdi-dev] @ThreadScoped?

Sun Mar 20 16:37:16 EDT 2016

On Sun, Mar 20, 2016 at 6:36 PM, Manfred Riem <mnriem at gmail.com> wrote:

> Why is changing @RequestScoped out of the question?
>
> From my perspective when an AsyncContext is started the request is still
> there.
>
> It is just being served by a different thread.
>

With just AsyncContext the original request thread can end and a new thread
can write to the response. Both of them can access the request object after
the AsyncContext has been handed to the second thread. But the second
thread is not necessarily "connected" to anything, is it? It's just any
random thread that gets the AsyncContext object passed in.

Would it work here if there was a public CDI API available to activate the
request scope (and session scope possibly) from a given instance
of ServletRequest?

Regardless, this is a slightly different problem from when a given request
thread submits work to a Concurrency spec executor.

Kind regards,
Arjan Tijms

>
> Certainly there is a need to work with the Servlet EG to figure out how to
> transfer “ownership” to the AsyncContext.
>
> Anyway my 2 cents
>
> Thanks!
>
> Kind regards,
> Manfred Riem
>
> On Mar 19, 2016, at 3:35 PM, Stephan Knitelius <stephan at knitelius.com>
> wrote:
>
> I would certainly agree with the assertion that in general it's not
> advisable to execute a request with multiple threads and that usually
> single threaded execution is sufficient.
>
> However I don't think ignoring it is an option. Concurrent operations can
> be launched even from CDI beans. Yet we don't properly support context
> propagation nor a context spanning all threads launched from a request.
>
> I know that changing @requestScoped is probably out of the question, but
> at least we should consider adding a new context spanning all threads and
> defining a logical solution for context propagation that can be explained
> to the end user.
>
>
>
> On Fr., 11. März 2016 at 17:17, Mark Struberg <struberg at yahoo.de> wrote:
>
>> Yes, but certain things in EE are assumed to be handled on a single
>> thread. And if you run on a servr then this is really not a blocker most
>> times. If I get many paralllel requests hitting my box then I do not need
>> async handling _that_ often. The whole overhead for setting up the new
>> thread, etc often heavily exceeds the benefits.
>> So I would not put too much energy into it…
>>
>> LieGrue,
>> strub
>>
>> > Am 11.03.2016 um 15:44 schrieb Reza Rahman <reza_rahman at lycos.com>:
>> >
>> > This is essentially in keeping with the minimalist nature of the EE
>> concurrency JSR. I believe most of it is left to vendors to do the right
>> thing for users. May be a good idea is this language can be tightened up.
>> >
>> >> On Mar 11, 2016, at 6:01 AM, Mark Struberg <struberg at yahoo.de> wrote:
>> >> E
>> >> From the servlet spec:
>> >>
>> >> „Java Enterprise Edition features such as Section 15.2.2, “Web
>> Application Environment” on page 15-174 and Section 15.3.1, “Propagation of
>> Security Identity in EJBTM Calls” on page 15-176 are available only to
>> threads executing the initial request or when the request is dispatched to
>> the container via the AsyncContext.dispatch method. Java Enterprise Edition
>> features may be available to other threads operating directly on the
>> response object via the AsyncContext.start(Runnable) method.“
>> >>
>> >> check „available only to threads executing the initial request“
>> >>
>> >> Also if you look at the servlet AsyncContext then all the wording is
>> written as MAY and not as MUST.
>> >>
>> >> LieGrue,
>> >> strub
>> >>
>> >>
>> >>> Am 10.03.2016 um 19:52 schrieb Romain Manni-Bucau <
>> rmannibucau at gmail.com>:
>> >>>
>> >>> Hi Mark,
>> >>>
>> >>> think 2.3.3.4 states the opposite.
>> >>>
>> >>>
>> >>> Romain Manni-Bucau
>> >>> @rmannibucau |  Blog | Github | LinkedIn | Tomitriber
>> >>>
>> >>> 2016-03-10 19:43 GMT+01:00 Mark Struberg <struberg at yahoo.de>:
>> >>> Back from JavaLand conference, so sorry for not kicking in earlier.
>> >>>
>> >>> I not quite get the argumentation chain. It’s that all triggered by
>> async servlet requests? And isn’t the servlet spec also saying that all the
>> request param etc may max be assigned to a single thread AT A TIME!
>> >>>
>> >>> Means that it might not be on multiple threads in parallel, but the
>> data is allowed to get moved from one thread to another (disapearing from
>> the first one), right?
>> >>> Would really need to dig into the wording of the async servlets spec
>> again, maybe has this in the back of his head?
>> >>>
>> >>> LieGrue,
>> >>> strub
>> >>>
>> >>>
>> >>>
>> >>>
>> >>>> Am 08.03.2016 um 14:43 schrieb Romain Manni-Bucau <
>> rmannibucau at gmail.com>:
>> >>>>
>> >>>> Hi guys,
>> >>>>
>> >>>> following request scope thread and to center the discussion on the
>> thread safety part: do we work on this?
>> >>>>
>> >>>> Background: @RequestScoped is often used as a ThreadLocal instance
>> solution. A lot of SE or Batch implementations rely on it from what I saw
>> as well as async implementations reusing existing business logic with this
>> thread safety constraint.
>> >>>>
>> >>>> Proposal: providing a @ThreadScoped implementation is cheap for CDI
>> and implemenation and would avoid the headache we can have with
>> @RequestScoped. Will also remove the quite dark side of the spec regarding
>> servlet request and request scope since now we would have a more natural
>> solution for all of these situation so @RequestScoped goals wouldn't
>> collide as much.
>> >>>>
>> >>>> Questions:
>> >>>> - is it automatically started as request scoped is (JMS, @Async,
>> ...)? Alternative could be some configuration in beans.xml (merged accross
>> the app):
>> >>>>
>> >>>> <beans>
>> >>>> <scopes>
>> >>>>   <thread>
>> >>>>     <active>JMS</active>
>> >>>>     <active>ASYNCHONOUS</active>
>> >>>>   </thread>
>> >>>> </scopes>
>> >>>> </beans>
>> >>>>
>> >>>> - start/stop API (this is typically an API the user should be able
>> to control for its own threads)
>> >>>> - CDI 2.*0*?
>> >>>>
>> >>>> wdyt?
>> >>>>
>> >>>> Romain Manni-Bucau
>> >>>> @rmannibucau |  Blog | Github | LinkedIn | Tomitriber
>> >>>> _______________________________________________
>> >>>> cdi-dev mailing list
>> >>>> cdi-dev at lists.jboss.org
>> >>>> https://lists.jboss.org/mailman/listinfo/cdi-dev
>> >>>>
>> >>>> Note that for all code provided on this list, the provider licenses
>> the code under the Apache License, Version 2 (
>> http://www.apache.org/licenses/LICENSE-2.0.html). For all other ideas
>> provided on this list, the provider waives all patent and other
>> intellectual property rights inherent in such information.
>> >>>
>> >>>
>> >>
>> >>
>> >> _______________________________________________
>> >> cdi-dev mailing list
>> >> cdi-dev at lists.jboss.org
>> >> https://lists.jboss.org/mailman/listinfo/cdi-dev
>> >>
>> >> Note that for all code provided on this list, the provider licenses
>> the code under the Apache License, Version 2 (
>> http://www.apache.org/licenses/LICENSE-2.0.html). For all other ideas
>> provided on this list, the provider waives all patent and other
>> intellectual property rights inherent in such information.
>> >
>> > _______________________________________________
>> > cdi-dev mailing list
>> > cdi-dev at lists.jboss.org
>> > https://lists.jboss.org/mailman/listinfo/cdi-dev
>> >
>> > Note that for all code provided on this list, the provider licenses the
>> code under the Apache License, Version 2 (
>> http://www.apache.org/licenses/LICENSE-2.0.html). For all other ideas
>> provided on this list, the provider waives all patent and other
>> intellectual property rights inherent in such information.
>>
>>
>> _______________________________________________
>> cdi-dev mailing list
>> cdi-dev at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/cdi-dev
>>
>> Note that for all code provided on this list, the provider licenses the
>> code under the Apache License, Version 2 (
>> http://www.apache.org/licenses/LICENSE-2.0.html). For all other ideas
>> provided on this list, the provider waives all patent and other
>> intellectual property rights inherent in such information.
>
> _______________________________________________
> cdi-dev mailing list
> cdi-dev at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/cdi-dev
>
> Note that for all code provided on this list, the provider licenses the
> code under the Apache License, Version 2 (
> http://www.apache.org/licenses/LICENSE-2.0.html). For all other ideas
> provided on this list, the provider waives all patent and other
> intellectual property rights inherent in such information.
>
>
>
> _______________________________________________
> cdi-dev mailing list
> cdi-dev at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/cdi-dev
>
> Note that for all code provided on this list, the provider licenses the
> code under the Apache License, Version 2 (
> http://www.apache.org/licenses/LICENSE-2.0.html). For all other ideas
> provided on this list, the provider waives all patent and other
> intellectual property rights inherent in such information.
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.jboss.org/pipermail/cdi-dev/attachments/20160320/7e846129/attachment.html 