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Re: OrderedScheduler and OrderedSafeExecutor


One other thing that is not clear to me is why we need delayed execution
AND key ordering.

Shouldn't be fine to retry later in a random thread? If the requirement is
to do something from a specific thread, we can also jump into that thread
when the delay task is finally executed.


On Sat, Mar 24, 2018 at 11:16 AM Sijie Guo <guosijie@xxxxxxxxx> wrote:

> On Sat, Mar 24, 2018 at 8:38 AM, Matteo Merli <mmerli@xxxxxxxxxx> wrote:
>
> > While profiling the allocations of a BookKeeper client (from current
> > master) writing entries, I've noticed that there are multiple allocations
> > per entry related to the OrderedScheduler.
> >
> > I think OrderedScheduler was introduced in 4.6 and now
> OrderedSafeExecutor
> > is just an extension of OrderedScheduler as well.
> >
>
> OrderedSafeExecutor extends OrderedScheduler was for BC. We made common
> util classes in bookkeeper-common.
>
>
> >
> > The main problem is that since OrderedScheduler supports both immediate
> and
> > delayed execution, it uses a ScheduledThreadPoolExecutor per each bucket,
> > plus some decorating wrappers.
> >
>
> Sound like this is the solution:
>
> - Keep the OrderedScheduler
> - Copy the OrderedScheduler to OrderedExecutor and change it to the
> original executor implementation
> - Let OrderedSafeScheduler extends OrderedExecutor (bc purpose)
>
>
> >
> > The ScheduledThreadPoolExecutor, needs a Priority queue and also always
> > return future objects.
> >
> > From my memory snapshot I have counted 12 objects allocated (per addEntry
> > operation) for a total of 472 bytes per each entry, all due the scheduled
> > executor.
> >
> > I think the delayed execution is only used in unit tests. In critical
> paths
> > we're only using the immediate task submission.
> >
> > I think it might be worth to refactor OrderedScheduler or
> > OrderedSafeExecutor to avoid that overhead.
> >
> > Thoughts?
> >
> > Matteo
> > --
> > Matteo Merli
> > <mmerli@xxxxxxxxxx>
> >
>
-- 
Matteo Merli
<mmerli@xxxxxxxxxx>