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From Alexey Goncharuk <alexey.goncha...@gmail.com>
Subject Re: async operation is not fair async
Date Wed, 16 May 2018 09:14:31 GMT
Dmitriy,

I will add technical details to the ticket, however, looks like there is
still no consensus on how this change should be presented to a user. It
would be ok if we changed this behavior in Ignite 3.0, but for one of the
next point releases we have to agree how this should be enabled/disabled
(or whether we should delay this change to 3.0 at all).

2018-05-15 22:13 GMT+03:00 Dmitriy Govorukhin <dmitriy.govorukhin@gmail.com>
:

>  Alexey,
>
> Any updates?
>
> On Mon, May 14, 2018 at 6:19 PM, Dmitriy Govorukhin <
> dmitriy.govorukhin@gmail.com> wrote:
>
> > Alexey,
> >
> > Could you please add more description information for this task? [1]
> > Perhaps, base steps for implementation.
> >
> > [1] https://issues.apache.org/jira/browse/IGNITE-8475
> >
> > On Mon, May 14, 2018 at 4:58 PM, Alexey Goncharuk <
> > alexey.goncharuk@gmail.com> wrote:
> >
> >> Another +1 for the true asynchronous approach. I remember a while ago
> one
> >> of the Ignite users raised a similar question regarding the *async
> method
> >> being blocked on establishing a TCP connection.
> >>
> >> As far as deadlocks go, I have a counter-example. Currently, we check
> the
> >> thread-local chain only for a single cache, so if I run the following
> >> code:
> >> cache1.getAsync(k1);
> >> cache2.getAsync(k2);
> >> then the deadlock is still possible, and I did not see a single user
> >> complaining about unexpected deadlocks. Rather than implementing this
> >> cross-cache chain (which would probably add another overhead), I would
> >> make
> >> it consistent and allow operations to be run in parallel.
> >>
> >> There are many use-cases when having true async operations dramatically
> >> improve performance. Consider, for example, a streaming example when
> keys
> >> are being pushed by a client to a cluster. Currently, to run effective
> >> processing, the user will have to use a data streamer with custom keys
> >> receiver which may be a huge usability downside. Async operations can
> >> utilize the cluster resources very efficiently.
> >>
> >> Finally, if we want to be on the safe side, we can keep the operation
> >> chain
> >> inside a transaction. I see absolutely no point in maintaining this
> chain
> >> outside of transactions.
> >>
> >> --AG
> >>
> >> 2018-05-14 16:01 GMT+03:00 Dmitriy Govorukhin <
> >> dmitriy.govorukhin@gmail.com>
> >> :
> >>
> >> > Andrey,
> >> >
> >> > Do you prefer change behavior at runtime?
> >> > I guess will be better have different methods for getting cache
> instance
> >> > with fair and not fair sync.
> >> >
> >> > On Mon, May 14, 2018 at 3:39 PM, Andrey Gura <agura@apache.org>
> wrote:
> >> >
> >> > > +1 for fair async operations.
> >> > >
> >> > > But I don't like idea use withFairSync() method. We added xxxAsync()
> >> > > methods recently and withAsync() is deprecated.
> >> > >
> >> > > I think we should just make methods are async in nature and provide
> >> > > ability of switching to the old behaviour using flag or property.
> >> > >
> >> > > On Fri, May 11, 2018 at 11:00 PM, Dmitriy Setrakyan
> >> > > <dsetrakyan@apache.org> wrote:
> >> > > > Vladimir,
> >> > > >
> >> > > > In general I agree, but I do get greatly *close-minded* (pun
> >> intended)
> >> > > > whenever users' code that worked for the past several years all
> of a
> >> > > sudden
> >> > > > gets deadlocked after an upgrade. Making this feature optional
is
> >> even
> >> > > > worse and more confusing. In this case the best action is no
> action
> >> at
> >> > > all.
> >> > > >
> >> > > > BTW, would be interesting to find out how Oracle async driver
> >> behaves
> >> > in
> >> > > > this case.
> >> > > >
> >> > > > D.
> >> > > >
> >> > > >
> >> > > >
> >> > > >
> >> > > >
> >> > > > On Fri, May 11, 2018 at 8:29 PM, Vladimir Ozerov <
> >> vozerov@gridgain.com
> >> > >
> >> > > > wrote:
> >> > > >
> >> > > >> Guys,
> >> > > >>
> >> > > >> To build a great product we should be open minded and look
to the
> >> > > future,
> >> > > >> not to the past.
> >> > > >>
> >> > > >> Dima raised very valid point - why async is not async? Current
> >> > > programming
> >> > > >> culture and demanding performance requirements pushes users
> towards
> >> > > >> reactive-style programming. I do not want my thread to ever
be
> >> > blocked.
> >> > > >> Instead, I want to send a number of concurrent commands and
> >> optionally
> >> > > >> subscribe to final result. So trully async API makes total
sense
> to
> >> > me.
> >> > > >>
> >> > > >> But personally, my primary interest in this area is SQL.
Oracle
> is
> >> > > >> preparing new async driver. ADBA - async database access.
It was
> >> > > presented
> >> > > >> on recent JavaOne [1]. It is under active development right
now -
> >> juse
> >> > > >> weave through the mailing list [2]. Some prototypes are already
> >> there
> >> > > [3].
> >> > > >> PostgreSQL community even started adopted it [4]!
> >> > > >>
> >> > > >> I am not pushing for immediate actions, but at least we should
> >> > > understand
> >> > > >> which way the wind is blowing. As a mid-term goals I would
> propose
> >> to
> >> > > >> finally remove thread ID from our PESSIMISTIC transactions
to
> allow
> >> > for
> >> > > >> suspend/resume in different threads. And as a next step I
would
> >> think
> >> > on
> >> > > >> adopting async cache and SQL APIs.
> >> > > >>
> >> > > >> Vladimir.
> >> > > >>
> >> > > >> [1]
> >> > > >> http://www.oracle.com/technetwork/database/
> >> > > application-development/jdbc/
> >> > > >> con1491-3961036.pdf
> >> > > >> [2] http://mail.openjdk.java.net/pipermail/jdbc-spec-discuss/
> >> > > >> [3] https://github.com/oracle/oracle-db-examples/tree/master/
> >> java/AoJ
> >> > > >> [4] https://github.com/pgjdbc/pgjdbc/issues/978
> >> > > >>
> >> > > >> On Fri, May 11, 2018 at 9:48 PM, Dmitriy Setrakyan <
> >> > > dsetrakyan@apache.org>
> >> > > >> wrote:
> >> > > >>
> >> > > >> > On Fri, May 11, 2018 at 7:46 PM, Dmitriy Govorukhin
<
> >> > > >> > dmitriy.govorukhin@gmail.com> wrote:
> >> > > >> >
> >> > > >> > > I will edit IGNITE-8475, and remove all part that
belong to
> the
> >> > > public
> >> > > >> > api.
> >> > > >> > > Is it acceptable for you?
> >> > > >> > >
> >> > > >> >
> >> > > >> > Everything is acceptable, as long as the public API
is safe :)
> >> > > >> >
> >> > > >>
> >> > >
> >> >
> >>
> >
> >
>

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