[infinispan-dev] Distributed executors and Future(s) they return

[Sanne Grinovero]

I'm a bit skeptical.
It might sound a sensible request currently, but if you do so you
inherently "promise" that tasks are going to be executed on a specific
server; AFAIK we promise execution on data locality, but maintaining a
good level of flexibility you can evolve your system to smarter load
balancing of tasks, failover operations, etc..
If you expose execution details, you won't be able to develop any of
that in future.

To make an example from the database world - seems the analogy is
common these days - it's like you run a SELECT statement but want to
pick which CPU core is going to be used. That would be really odd, as
you would take away the option from the scheduler to make an effective
choice.
Still, this approach might be desirable for a database which doesn't
do any smart scheduling.

Some of these concerns might be mitigated if you return the Address of
where the task *was* executed, after it's done. I still don't think it
should be of user's interest but at least you would be able to
implement rescheduling or failover policies in future.

Sanne


On 26 February 2014 19:31, Vladimir Blagojevic <vblagoje at redhat.com> wrote:
> Hey,
>
> There is an interesting request from community to include an Address along with a Future returned for a subtask being executed [1].
>
> I think it makes sense what this user wants. We might create Future sub interface that has getAddress method and we can return an object implementing that interface instead of plain Future. In some new major release we can officially change the signature of these DistributedExecutorService methods to return i.e TargetedFuture - it would not break existing clients. Maybe even make TargetedFuture extend NotifyingFuture.
>
> Any thoughts?
>
> Vladimir
>
> [1] https://community.jboss.org/thread/237442
>
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