[wildfly-dev] EJB Transactions Graceful Shutdown

[Richard Achmatowicz]

Hi Flavia

Is there any overall design for this feature available to browse? For 
example, there has long been a problem (and still is) with remotely 
initiated transactions and the EJB client retry mechanism (both of them) 
which associates an XA resource with one node at the beginning of the 
transaction and then retries on another, completes on the other, then 
tries to commit on the original XA node which has shutdown. This is 
anything but clean.

Richard


On 02/12/16 11:56 AM, Flavia Rainone wrote:
>
> Hi,
>
> I'm creating this thread to discuss the remaining details of graceful 
> shutdown for ejb transactions.
>
> This is more or less what I've done so far:
>
> https://github.com/fl4via/wildfly/commit/7017146522af9a979a8a8e0c92039e6a5fb18760
>
> While discussing this in the hip chat yesterday, Stuart mentioned that 
> maybe we could have the transactions subsystem responsible for keeping 
> track of how many active transactions we have, instead of putting that 
> code in EjbRemoteTransactionsRepository.
>
> Stuart, does that include having the suspend callback being done at 
> transactions subsystem as well? I'm thinking maybe not, because there 
> are two points in the ejb subsystem we need to know if transactions 
> suspension is over:
>
> - at EjbSuspendInterceptor if it is over, no request is allowed, if it 
> is not over, we need to check if current invocation contains a 
> reference to an active transaction
>
> - at some point, we need to let control point notify that the ejb 
> module is no longer available to ejb client after transaction 
> suspension is over, i.e., we need to do that when suspend has been 
> requested and there are no remaining active transactions available.
>
> On the other hand, it is hard to draw the line between what should be 
> in the transactions subsystem and what shouldn't. If the callback is 
> done at transactions subsystem, we need a way of having ejb3 notified 
> that it is done. If it is not done at transactions subsystem, ejb3 has 
> to be notified of the active transactions going to zero, which seems a 
> lot of overhead, so from this point of view maybe the callback should 
> be in the transactions system after all.
>
> Stuart and Gytis, any thoughts?
> -- 
> Flavia Rainone
> Principal Software Engineer
> JBoss EAP/WildFly Team
> M: (+55) 11 981-225-466
>
> Red Hat.
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>
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