I am re-reading the spec end to end again right now. So far it seems I have remembered
everything correctly.
You should read over section 2.3. What it is saying is that a container implementing the
Java EE concurrency utilities should ensure whatever contextual information is needed for
managed components to work correctly should be propagated automatically. For the correct
implementation of CDI scopes, this should also mean any currently active scopes. The
section you are referring to is basically implying that thinking that it is possible to
use these scoped beans in tasks (albeit not reliably since beans could go out of scope
before the thread finishes - for example if the request ends).
This does not have anything to do with the context service per se. The context service is
an SPI of sorts to allow end user developers to do for their own applications what the
container does behind the scenes for managed component context propagation.
I'll read over the entire spec to see if there is anything to contradict this. If
that's not the case what Romain is describing is most likely an implementation
specific bug that did not take into account CDI scope propagation.
On Mar 6, 2016, at 4:23 PM, John D. Ament
<john.d.ament(a)gmail.com> wrote:
Reza,
I read through the concurrency utils spec. Was there a specific section you had in mind?
The only references to CDI were near the beginning warning users to not use
Request/Session scoped beans as tasks since the outer most context may be destroyed before
the work is done.
I have a feeling what you're referring to is the context service:
http://docs.oracle.com/javaee/7/api/javax/enterprise/concurrent/ContextSe...
If that's the case, then basically this should work OOTB right?
Task task = new MyTask();
task = contextService.createContextualProxy(task, Task.class);
executor.submit(task);
// now magically the context should be prop'd?
Is that about right?
John
> On Sun, Mar 6, 2016 at 3:30 PM Reza Rahman <reza_rahman(a)lycos.com> wrote:
> Have you actually looked at the EE concurrency spec text in detail? What does it say
about managed component context propagation?
>
> Without actually doing that further discussing this is just taking shots in the dark.
As an implementer it should not surprise you that this might simply be a bug because the
person implementing the concurrency utilities for the EE runtime was not told about what
to copy over into the new thread for CDI to work correctly.
>
>> On Mar 6, 2016, at 3:06 PM, Romain Manni-Bucau <rmannibucau(a)gmail.com>
wrote:
>>
>>
>> 2016-03-06 20:59 GMT+01:00 Reza Rahman <reza_rahman(a)lycos.com>:
>>> As far as I know this is precisely the sort of thing that the EE concurrency
spec is intended for. It is supposed to copy over everything from the underlying thread
local context into the new thread for all EE managed components to function. Since CDI
beans are also EE container managed, it also applies to CDI beans as well. The EE vendor
is supposed to make sure this works properly.
>>>
>>> I don't think the concurrency utilities specifically lists APIs for which
thread context propagation should work. If this doesn't work in a specific
implementation it's most likely because they didn't take CDI into account in their
own EE concurrency implementation.
>>
>> That's what I wanted/would like. CDI TCK breaks it quite easily and
@RequestScoped which is *used* today is sadly a @ThreadLocalScoped badly named. So to
solve it we would need another scope as I mentionned several times on this list 100%
matching servlet instances lifecycles (on a pure CDI side we have the same issue for
sessions which are recycled during a request, the session scope is corrupted *by spec* in
term of user behavior).
>>
>>>> On Mar 6, 2016, at 2:45 PM, John D. Ament <john.d.ament(a)gmail.com>
wrote:
>>>>
>>>> The section of the spec you link to makes no references to threads. 6.3
makes some notes about normal scopes and threads, and specifically says that a context is
bound to one or more threads.
>>>>
>>>> I think what's happened is that over the years, people have simply
bound HTTP Request == single thread, but when async processing was introduced no one
thought to clarify that the spawning of a child thread from the original HTTP request
retains the parent's context.
>>>>
>>>> This is another requested feature, but looks more like a bug or gap in
the spec.
>>>>
>>>> John
>>>>
>>>>> On Sun, Mar 6, 2016 at 2:37 PM Romain Manni-Bucau
<rmannibucau(a)gmail.com> wrote:
>>>>> 2016-03-06 20:25 GMT+01:00 Reza Rahman
<reza_rahman(a)lycos.com>:
>>>>>> Let's see. I suspect the specification text for EE
concurrency is generic enough for implementations to also be able to cover CDI scopes or
any other Java EE API context propagation needs. This means the issue needs to be solved
at the individual implementation level. Changing anything in the spec is probably just
unnecessary ceremony in this case.
>>>>>
>>>>> Then 1. concurrency- utility can't be reliable for "EE"
users, 2. CDI still prevent it to work since it would violate the spec to propagate it
while request scope is bound to another thread
(
http://docs.jboss.org/cdi/spec/1.1/cdi-spec.html#request_context handles async listener
but not the main AsyncContext part).
>>>>>
>>>>>>> On Mar 6, 2016, at 2:15 PM, Romain Manni-Bucau
<rmannibucau(a)gmail.com> wrote:
>>>>>>>
>>>>>>>
>>>>>>> 2016-03-06 19:42 GMT+01:00 Reza Rahman
<reza_rahman(a)lycos.com>:
>>>>>>>> This frankly surprises me. I'll check the
specification text. This might indeed just be an implementation bug. The EE concurrency
utilities are supposed to be copying all relevant context. If this is an issue than it has
to be that it is not copying enough of the HTTP request context for CDI to work.
>>>>>>>
>>>>>>> The issue is not technical since I got it working but needed
to reverse. From my understanding ee concurrency utilities was done in a time CDI was not
there so it just ignored it somehow and it hasnt been updated when integrated to the spec.
Now with the wording of the CDI - and TCK - it is impossible to make it working since
request scope is bound the thre request thread - and not the request. Side note: same
applies to session scope and conversation.
>>>>>>>
>>>>>>>> Surely the Red Hat folks can quickly shed some light here
since they implement essentially this whole stack?
>>>>>>>>
>>>>>>>>> On Mar 6, 2016, at 1:30 PM, Romain Manni-Bucau
<rmannibucau(a)gmail.com> wrote:
>>>>>>>>>
>>>>>>>>> 2016-03-06 19:20 GMT+01:00 Reza Rahman
<reza_rahman(a)lycos.com>:
>>>>>>>>>> Can you kindly try to make the example a bit
simpler? It's important to make the case for how likely this is supposed to occur in
most business applications.
>>>>>>>>>>
>>>>>>>>>> Also, other than making sure that the executor
service is propagating thread local request contexts correctly what other solution are you
proposing? Did you check the specification? How sure are you that this isn't simply an
implementation bug?
>>>>>>>>>>
>>>>>>>>>> As far as I know the executor service is supposed
to be preserving all relevant parts of the EE context?
>>>>>>>>>
>>>>>>>>> Not in concurrency-utilities for EE at least. That
was the first impl I did then Mark pointed out it was violating CDI spec and request scope
definition. There is a kind of contracdiction there cause concurrency-utilities
doesn't integrate with CDI at all but we can also see it the opposite way: CDI
doesn't provide any way to propagate a context in another thread. Both point of view
are valid so we need to see where we tackle it.
>>>>>>>>>
>>>>>>>>>>> On Mar 6, 2016, at 12:35 PM, Romain
Manni-Bucau <rmannibucau(a)gmail.com> wrote:
>>>>>>>>>>>
>>>>>>>>>>> does
https://gist.github.com/rmannibucau/d55fce47b001185dca3e help?
>>>>>>>>>>>
>>>>>>>>>>> Idea is to give an API to make:
>>>>>>>>>>>
>>>>>>>>>>> public void complete() {
>>>>>>>>>>> try {
>>>>>>>>>>>
asyncContext.complete();
>>>>>>>>>>> } finally {
>>>>>>>>>>> auditContext.end();
>>>>>>>>>>> }
>>>>>>>>>>> }
>>>>>>>>>>>
>>>>>>>>>>> working without hacky and almost impossible
context pushing (cause of injections nature you are not supposed to know what to push in
the context when going async).
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Romain Manni-Bucau
>>>>>>>>>>> @rmannibucau | Blog | Github | LinkedIn |
Tomitriber
>>>>>>>>>>>
>>>>>>>>>>> 2016-03-06 16:40 GMT+01:00 Reza Rahman
<reza_rahman(a)lycos.com>:
>>>>>>>>>>>> Can you kindly share an annotated code
example of the proposed solution so we can all follow and discuss this?
>>>>>>>>>>>>
>>>>>>>>>>>> On Mar 6, 2016, at 9:31 AM, Romain
Manni-Bucau <rmannibucau(a)gmail.com> wroteshar:
>>>>>>>>>>>>
>>>>>>>>>>>>> Hi guys,
>>>>>>>>>>>>>
>>>>>>>>>>>>> spoke on concurrency utilities about
the ability to inherit a cdi scope. Idea is to follow request scope more than cdi spec
allows. First thought it was a concurrency utilities thing but Reza mentionned can be a
CDI one so here it is.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Sample:
>>>>>>>>>>>>> In a servlet i get MyBean which is
@RequestScoped, I do some set on it. The i go async (AsyncContext) and trigger a task in
another thread. It would be neat - and mandatory in some case by the loose coupling nature
of CDI - to get the *same* MyBean *instance* in this thread. With a direct dependency you
can easily use message passing pattern - but you loose the loose coupling cause you need
to know until which level you unwrap, think t principal case which has 2-3 proxies!.
However in practice you have a lot of undirect dependencies, in particular with enterprise
concerns (auditing, security...) so you can't really do it easily/naturally.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Bonus:
>>>>>>>>>>>>> One very verbose way is to be able to
kind of push/pop an existing context in a thread - wrappers doing it on a
Runnable/Consumer/Function/... would be neat.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Question:
>>>>>>>>>>>>> Would CDI handle it in 2.0?
>>>>>>>>>>>>>
>>>>>>>>>>>>> Side note: this is really about the
fact to reuse a "context context" (its current instances map) in another thread
the more transparently possible and match the user vision more than a technical question
for now.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Romain Manni-Bucau
>>>>>>>>>>>>> @rmannibucau | Blog | Github |
LinkedIn | Tomitriber
>>>>>>>>>>>>>
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