[cdi-dev] Enhancing SPI to support async operation for contexts

[Sven Linstaedt]

Hi,

and sorry for spontaneously dropping in. Just to clarify some personal
questions/assumptions:

1. Regarding threading the current spec only states that "A context may be
associated with one or more threads".

2. It is nowhere stated that @RequestScoped beans are inherently thread
safe. Thread safety was implied from the servlet spec, because the scope
backing container (ServletRequest#attributes) was executed single threaded.

3. With Servlet 3.0 the same ServletRequest#attributes is available for
access from multiple threads via  ServletRequest#startAsync(), so
containing objects may have a need for synchronization.

4. Why does CDI 2.0 has to care about thread safety of @RequestScoped
beans? If the application is for some reason setting the request in async
mode, the application must also ensure, it's containing and accessed beans
are thread safe.


Best regards
Sven

2015-02-19 11:22 GMT+01:00 Romain Manni-Bucau <rmannibucau at gmail.com>:

> Hi
>
> I'm +1 for it but it needs important changes (= surely new contexts).
> Typically we can't change today @RequestScoped (which has no link with
> a request but only with a thread!).
>
> So we could have @RequestScoped (~ @ThreadLocalScoped) and
> @InheritedRequestScoped which would be a real request scope (but not
> an InheritedThreadLocal please)
>
> For the request it makes a lot of sense since you need to stay thread
> safe even accross threads (servlet spec) and avoids to be forced to
> use message passing which - even if a good pattern - adds boilerplate
> code for simple async needs.
>
> For JAXRS I dont know since it is really suspend/resume semantic so
> request scope maybe doesnt makes much sense here (there is a break in
> the flow).
>
>
>
> Romain Manni-Bucau
> @rmannibucau
> http://www.tomitribe.com
> http://rmannibucau.wordpress.com
> https://github.com/rmannibucau
>
>
> 2015-02-19 10:32 GMT+01:00 Antoine Sabot-Durand <antoine at sabot-durand.net
> >:
> > Hi All,
> >
> > Beyond the asynchronous event case, shouldn’t we provide a way for user
> to launch async treatments in CDI with the possibility to keep the existing
> contexts at the moment of async operation launch?
> > Today servlet or JAX-RS spec support async call without the loss of
> request for instance. Shouldn’t we think to something like that?
> >
> > Thanks for your input on that point.
> >
> > Antoine
> >
> >
> >
> >
> >
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