(1) should work, but as Jun suggested earlier in the thread it is
slightly misleading. The (intuitive) post-condition of "close" is that
the producer has shutdown - i.e., its sender thread, closed its
metrics, serializer/deserializer, etc. That is not necessarily a
post-condition of "close(0)" although one can contend that if you call
the method in non-blocking mode (zero timeout) then it is reasonable
to not expect that post-condition.
So I think that although (2) adds one more API it brings "simplicity
by virtue of overall clarity".
I would be in favor of (2) but not strongly opposed to (1).
Thanks,
Joel
On Thu, Mar 19, 2015 at 10:05:04AM -0700, Neha Narkhede wrote:
> I'm in favor of (1) for the sake of simplicity and as Jay mentions to
> reduce the number of different APIs. Can you explain when (1) does not work?
>
> On Wed, Mar 18, 2015 at 2:52 PM, Jay Kreps <jay.kr...@gmail.com> wrote:
>
> > Personally I'm in favor of (1) just to reduce the number of different APIs.
> > People will find the difference between abort and close subtle and
> > confusing and the only instance where you want it is this somewhat unusual
> > case you guys are pursuing, right?
> >
> > -Jay
> >
> > On Wed, Mar 18, 2015 at 2:13 PM, Jiangjie Qin <j...@linkedin.com.invalid>
> > wrote:
> >
> > > It looks we have another option and are now deciding between the
> > following
> > > two interfaces:
> > >
> > > 1. Close() + close(timeout)
> > > - timeout could be either positive or zero.
> > > - only close(0) can be called from sender thread
> > >
> > > 2. Close() + abort() + close(timeout)
> > > - timeout can either be positive or zero
> > > - only abort() can be called from sender thread
> > >
> > > - abort() is equivalent to close(0) in 1) but does not join sender
> > > thread and does not close metrics.
> > > - Another thread has to call close() or close(timeout) in order to make
> > > sure the resources in producer are gone.
> > >
> > > The tow approach provides the same function we need, the difference is
> > > approach 2) follows convention of close() and abort(). On the other hand,
> > > approach 1) saves one interface compared with approach 2) but does not
> > > follow the convention.
> > >
> > > When the two approaches come to user code, it is probably something like
> > > this:
> > >
> > > Try {
> > > While(!finished)
> > > Producer.send(record, callback)
> > > } catch (Exception e) {
> > > Producer.close(5)
> > > }
> > >
> > > Class CallbackImpl implements Callback {
> > > onCompletion(RecordMetadata metadata Exception e) {
> > > If (e != null)
> > > Abort() / close()
> > > }
> > > }
> > >
> > > Because the two approach leads to almost the same user code, assuming
> > > users are always calling producer.close() as a clean up step, personally
> > I
> > > prefer approach 2) as it follows convention.
> > >
> > > Any thoughts?
> > >
> > > Jiangjie (Becket) Qin
> > >
> > >
> > > On 3/17/15, 10:25 AM, "Jiangjie Qin" <j...@linkedin.com> wrote:
> > >
> > > >Hi Jun,
> > > >
> > > >Yes, as Guozhang said, the main reason we set a flag is because close(0)
> > > >is expected to be called by sender thread itself.
> > > >If we want to maintain the semantic meaning of close(), one alternative
> > is
> > > >to have an abort() method does the same thing as close(0) except
> > cleanup.
> > > >And in close(timeout), after timeout we call abort() and join the sender
> > > >thread. This was one of the previous proposal. We merged abort to
> > close(0)
> > > >because they are almost doing the same thing. But from what you
> > mentioned,
> > > >it might make sense to have two separate methods.
> > > >
> > > >Thanks.
> > > >
> > > >Jiangjie (Becket) Qin
> > > >
> > > >On 3/16/15, 10:31 PM, "Guozhang Wang" <wangg...@gmail.com> wrote:
> > > >
> > > >>Yeah in this sense the sender thread will not exist immediately in the
> > > >>close(0) call, but will only terminate after the current response batch
> > > >>has
> > > >>been processed, as will the producer instance itself.
> > > >>
> > > >>There is a reason for this though: for a clean shutdown the caller
> > thread
> > > >>has to wait for the sender thread to join before closing the producer
> > > >>instance, but this cannot be achieve if close(0) is called by the
> > sender
> > > >>thread itself (for example in KAFKA-1659, there is a proposal from
> > Andrew
> > > >>Stein on using thread.interrupt and thread.stop, but if it is called by
> > > >>the
> > > >>ioThread itself the stop call will fail). Hence we came up with the
> > flag
> > > >>approach to let the sender thread to close as soon as it is at the
> > > >>barrier
> > > >>of the run loop.
> > > >>
> > > >>Guozhang
> > > >>
> > > >>On Mon, Mar 16, 2015 at 9:41 PM, Jun Rao <j...@confluent.io> wrote:
> > > >>
> > > >>> Hmm, does that mean that after close(0), the sender thread is not
> > > >>>necessary
> > > >>> gone? Normally, after closing an entity, we expect all internal
> > threads
> > > >>> associated with the entity are shut down completely.
> > > >>>
> > > >>> Thanks,
> > > >>>
> > > >>> Jun
> > > >>>
> > > >>> On Mon, Mar 16, 2015 at 3:18 PM, Jiangjie Qin
> > > >>><j...@linkedin.com.invalid>
> > > >>> wrote:
> > > >>>
> > > >>> > Hi Jun,
> > > >>> >
> > > >>> > Close(0) will set two flags in sender. Running=false and a newly
> > > >>>added
> > > >>> > forceClose=true. It will also set accumulator.closed=true so no
> > > >>>further
> > > >>> > producer.send() will succeed.
> > > >>> > The sender thread will finish executing all the callbacks in
> > current
> > > >>> batch
> > > >>> > of responses, then it will see the forceClose flag. It will just
> > fail
> > > >>>all
> > > >>> > the incomplete batches in the producer and exit.
> > > >>> > So close(0) is a non-blocking call and sender thread will not try
> > to
> > > >>>join
> > > >>> > itself in close(0).
> > > >>> >
> > > >>> > Thanks.
> > > >>> >
> > > >>> > Jiangjie (Becket) Qin
> > > >>> >
> > > >>> > On 3/16/15, 2:50 PM, "Jun Rao" <j...@confluent.io> wrote:
> > > >>> >
> > > >>> > >How does close(0) work if it's called from the sender thread? If
> > > >>> close(0)
> > > >>> > >needs to wait for the sender thread to join, wouldn't this cause a
> > > >>> > >deadlock?
> > > >>> > >
> > > >>> > >Thanks,
> > > >>> > >
> > > >>> > >Jun
> > > >>> > >
> > > >>> > >On Mon, Mar 16, 2015 at 2:26 PM, Jiangjie Qin
> > > >>><j...@linkedin.com.invalid
> > > >>> >
> > > >>> > >wrote:
> > > >>> > >
> > > >>> > >> Thanks Guozhang. It wouldn’t be as thoroughly considered without
> > > >>> > >> discussing with you :)
> > > >>> > >>
> > > >>> > >> Jiangjie (Becket) Qin
> > > >>> > >>
> > > >>> > >> On 3/16/15, 1:07 PM, "Guozhang Wang" <wangg...@gmail.com>
> > wrote:
> > > >>> > >>
> > > >>> > >> >Thanks Jiangjie,
> > > >>> > >> >
> > > >>> > >> >After talking to you offline on this, I have been convinced and
> > > >>> > >>changed my
> > > >>> > >> >preference to blocking. The immediate shutdown approach does
> > have
> > > >>> some
> > > >>> > >> >unsafeness in some cases.
> > > >>> > >> >
> > > >>> > >> >Guozhang
> > > >>> > >> >
> > > >>> > >> >On Mon, Mar 16, 2015 at 11:50 AM, Jiangjie Qin
> > > >>> > >><j...@linkedin.com.invalid
> > > >>> > >> >
> > > >>> > >> >wrote:
> > > >>> > >> >
> > > >>> > >> >> It looks that the problem we want to solve and the purpose we
> > > >>>want
> > > >>> to
> > > >>> > >> >> achieve is:
> > > >>> > >> >> If user uses close() in callback, we want to let user be
> > aware
> > > >>>that
> > > >>> > >>they
> > > >>> > >> >> should use close(0) instead of close() in the callback.
> > > >>> > >> >>
> > > >>> > >> >> We have agreed that we will have an error log to inform user
> > > >>>about
> > > >>> > >>this
> > > >>> > >> >> mis-usage. The options differ in the way how we can force
> > user
> > > >>>to
> > > >>> > >>take a
> > > >>> > >> >> look at that error log.
> > > >>> > >> >> There are two scenarios:
> > > >>> > >> >> 1. User does not expect the program to exit.
> > > >>> > >> >> 2. User expect the program to exit.
> > > >>> > >> >>
> > > >>> > >> >> For scenario 1), blocking will probably delay the discovery
> > of
> > > >>>the
> > > >>> > >> >> problem. Calling close(0) exposes the problem quicker. In
> > this
> > > >>> > >>scenario
> > > >>> > >> >> producer just encounter a send failure when running normally.
> > > >>> > >> >> For scenario 2), blocking will expose the problem quick.
> > > >>>Calling
> > > >>> > >> >>close(-1)
> > > >>> > >> >> might hide the problem. This scenario might include: a) Unit
> > > >>>test
> > > >>> > >>for a
> > > >>> > >> >> send failure. b) Message sending during a close() call from a
> > > >>>user
> > > >>> > >> >>thread.
> > > >>> > >> >>
> > > >>> > >> >> So as a summary table:
> > > >>> > >> >>
> > > >>> > >> >> Scenario 1)
> > Scenario
> > > >>>2)
> > > >>> > >> >>
> > > >>> > >> >> Blocking Delay problem discovery Guaranteed
> > > >>>problem
> > > >>> > >> >>discovery
> > > >>> > >> >>
> > > >>> > >> >> Close(-1) Immediate problem discovery Problem might
> > be
> > > >>> hidden
> > > >>> > >> >>
> > > >>> > >> >>
> > > >>> > >> >> Personally I prefer blocking because it seems providing more
> > > >>> > >>guarantees
> > > >>> > >> >> and safer.
> > > >>> > >> >>
> > > >>> > >> >> Thanks.
> > > >>> > >> >>
> > > >>> > >> >> Jiangjie (Becket) Qin
> > > >>> > >> >>
> > > >>> > >> >>
> > > >>> > >> >> On 3/16/15, 10:11 AM, "Guozhang Wang" <wangg...@gmail.com>
> > > >>>wrote:
> > > >>> > >> >>
> > > >>> > >> >> >HI Jiangjie,
> > > >>> > >> >> >
> > > >>> > >> >> >As far as I understand calling close() in the ioThread is
> > not
> > > >>> > >>common,
> > > >>> > >> >>as
> > > >>> > >> >> >it
> > > >>> > >> >> >may only trigger when we saw some non-retriable error. Hence
> > > >>>when
> > > >>> > >>user
> > > >>> > >> >>run
> > > >>> > >> >> >their program it is unlikely that close() will be triggered
> > > >>>and
> > > >>> > >>problem
> > > >>> > >> >> >will be detected. So it seems to me that from the error
> > > >>>detection
> > > >>> > >> >>aspect
> > > >>> > >> >> >these two options seems to be the same as people will
> > usually
> > > >>> > >>detect it
> > > >>> > >> >> >from the producer metrics all dropping to 0.
> > > >>> > >> >> >
> > > >>> > >> >> >Guozhang
> > > >>> > >> >> >
> > > >>> > >> >> >On Mon, Mar 16, 2015 at 9:52 AM, Jiangjie Qin
> > > >>> > >> >><j...@linkedin.com.invalid>
> > > >>> > >> >> >wrote:
> > > >>> > >> >> >
> > > >>> > >> >> >> It seems there are two options we can choose from when
> > > >>>close()
> > > >>> is
> > > >>> > >> >>called
> > > >>> > >> >> >> from sender thread (callback):
> > > >>> > >> >> >> 1. Log an error and close the producer using close(-1)
> > > >>> > >> >> >> 2. Log an error and block.
> > > >>> > >> >> >> (Throwing an exception will not work because we catch all
> > > >>>the
> > > >>> > >> >>exception
> > > >>> > >> >> >> thrown from user callback. It will just lead to an error
> > > >>>log.)
> > > >>> > >> >> >>
> > > >>> > >> >> >> My concern for the first option is that the producer will
> > be
> > > >>> > >>closed
> > > >>> > >> >>even
> > > >>> > >> >> >> if we logged and error. I am wondering if some user would
> > > >>>not
> > > >>> even
> > > >>> > >> >>take
> > > >>> > >> >> >>a
> > > >>> > >> >> >> look at the log if producer is closed normally. Because
> > from
> > > >>>the
> > > >>> > >> >> >>programs
> > > >>> > >> >> >> behavior, everything looks good. If that is the case, the
> > > >>>error
> > > >>> > >> >>message
> > > >>> > >> >> >>we
> > > >>> > >> >> >> logged probably will just be ignored until some day when
> > > >>>people
> > > >>> > >>check
> > > >>> > >> >> >>the
> > > >>> > >> >> >> log and see it.
> > > >>> > >> >> >>
> > > >>> > >> >> >> As for the second option, because producer does not close
> > > >>>but
> > > >>> > >>blocks.
> > > >>> > >> >> >>User
> > > >>> > >> >> >> will notice this the first time they run the program. They
> > > >>> > >>probably
> > > >>> > >> >>will
> > > >>> > >> >> >> look at the log to see why producer could not be closed
> > and
> > > >>>they
> > > >>> > >>will
> > > >>> > >> >> >>see
> > > >>> > >> >> >> the error log we put there. So they will get informed
> > about
> > > >>>this
> > > >>> > >> >> >>mis-usage
> > > >>> > >> >> >> of close() in sender thread the first time they run the
> > code
> > > >>> > >>instead
> > > >>> > >> >>of
> > > >>> > >> >> >> some time later.
> > > >>> > >> >> >>
> > > >>> > >> >> >> Personally I prefer the second one because it is more
> > > >>>obvious
> > > >>> that
> > > >>> > >> >> >> something was wrong.
> > > >>> > >> >> >>
> > > >>> > >> >> >> Jiangjie (Becket) Qin
> > > >>> > >> >> >>
> > > >>> > >> >> >> On 3/15/15, 4:27 PM, "Guozhang Wang" <wangg...@gmail.com>
> > > >>> wrote:
> > > >>> > >> >> >>
> > > >>> > >> >> >> >Yeah I agree we should not silently change the behavior
> > of
> > > >>>the
> > > >>> > >> >>function
> > > >>> > >> >> >> >with the given parameters; and I would prefer
> > > >>> > >> >> >>error-logging-and-shutdown
> > > >>> > >> >> >> >over blocking when close(>0) is used, since as Neha
> > > >>>suggested
> > > >>> > >> >>blocking
> > > >>> > >> >> >> >would also not proceed with sending any data, bu will
> > just
> > > >>>let
> > > >>> > >> >>users to
> > > >>> > >> >> >> >realize the issue later than sooner.
> > > >>> > >> >> >> >
> > > >>> > >> >> >> >On Sun, Mar 15, 2015 at 3:25 PM, Neha Narkhede
> > > >>> > >><n...@confluent.io>
> > > >>> > >> >> >>wrote:
> > > >>> > >> >> >> >
> > > >>> > >> >> >> >> >
> > > >>> > >> >> >> >> > And I also agree it is better if we can make producer
> > > >>>block
> > > >>> > >>when
> > > >>> > >> >> >> >> > close() is called from sender thread so user will
> > > >>>notice
> > > >>> > >> >>something
> > > >>> > >> >> >> >>went
> > > >>> > >> >> >> >> > wrong.
> > > >>> > >> >> >> >>
> > > >>> > >> >> >> >>
> > > >>> > >> >> >> >> This isn't a great experience either. Why can't we just
> > > >>>throw
> > > >>> > >>an
> > > >>> > >> >> >> >>exception
> > > >>> > >> >> >> >> for a behavior we know is incorrect and we'd like the
> > > >>>user to
> > > >>> > >> >>know.
> > > >>> > >> >> >> >> Blocking as a means of doing that seems wrong and
> > > >>>annoying.
> > > >>> > >> >> >> >>
> > > >>> > >> >> >> >> On Sun, Mar 15, 2015 at 11:56 AM, Jay Kreps
> > > >>> > >><jay.kr...@gmail.com>
> > > >>> > >> >> >> wrote:
> > > >>> > >> >> >> >>
> > > >>> > >> >> >> >> > Cool.
> > > >>> > >> >> >> >> >
> > > >>> > >> >> >> >> > I think blocking is good or alternately throwing an
> > > >>> exception
> > > >>> > >> >> >>directly
> > > >>> > >> >> >> >> from
> > > >>> > >> >> >> >> > close(). Basically I would just worry about subtly
> > > >>>doing
> > > >>> > >> >>something
> > > >>> > >> >> >> >> slightly
> > > >>> > >> >> >> >> > different from what the user asked for as it will be
> > > >>>hard
> > > >>> to
> > > >>> > >> >>notice
> > > >>> > >> >> >> >>that
> > > >>> > >> >> >> >> > behavior difference.
> > > >>> > >> >> >> >> >
> > > >>> > >> >> >> >> > -Jay
> > > >>> > >> >> >> >> >
> > > >>> > >> >> >> >> > On Sat, Mar 14, 2015 at 5:48 PM, Jiangjie Qin
> > > >>> > >> >> >> >><j...@linkedin.com.invalid
> > > >>> > >> >> >> >> >
> > > >>> > >> >> >> >> > wrote:
> > > >>> > >> >> >> >> >
> > > >>> > >> >> >> >> > > Hi Jay,
> > > >>> > >> >> >> >> > >
> > > >>> > >> >> >> >> > > I have modified the KIP as you suggested. I thinks
> > as
> > > >>> long
> > > >>> > >>as
> > > >>> > >> >>we
> > > >>> > >> >> >> >>have
> > > >>> > >> >> >> >> > > consistent define for timeout across Kafka
> > interface,
> > > >>> there
> > > >>> > >> >>would
> > > >>> > >> >> >> >>be no
> > > >>> > >> >> >> >> > > problem. And I also agree it is better if we can
> > make
> > > >>> > >>producer
> > > >>> > >> >> >>block
> > > >>> > >> >> >> >> when
> > > >>> > >> >> >> >> > > close() is called from sender thread so user will
> > > >>>notice
> > > >>> > >> >> >>something
> > > >>> > >> >> >> >>went
> > > >>> > >> >> >> >> > > wrong.
> > > >>> > >> >> >> >> > >
> > > >>> > >> >> >> >> > > Thanks.
> > > >>> > >> >> >> >> > >
> > > >>> > >> >> >> >> > > Jiangjie (Becket) Qin
> > > >>> > >> >> >> >> > >
> > > >>> > >> >> >> >> > > On 3/14/15, 11:37 AM, "Jay Kreps"
> > > >>><jay.kr...@gmail.com>
> > > >>> > >> wrote:
> > > >>> > >> >> >> >> > >
> > > >>> > >> >> >> >> > > >Hey Jiangjie,
> > > >>> > >> >> >> >> > > >
> > > >>> > >> >> >> >> > > >I think this is going to be very confusing that
> > > >>> > >> >> >> >> > > > close(0) waits indefinitely and
> > > >>> > >> >> >> >> > > > close(-1) waits for 0.
> > > >>> > >> >> >> >> > > >I understand this appears in other apis, but it
> > is a
> > > >>> > >>constant
> > > >>> > >> >> >> >>cause of
> > > >>> > >> >> >> >> > > >bugs. Let's not repeat that mistake.
> > > >>> > >> >> >> >> > > >
> > > >>> > >> >> >> >> > > >Let's make close(0) wait for 0. We don't need a
> > way
> > > >>>to
> > > >>> > >>wait
> > > >>> > >> >> >> >> indefinitely
> > > >>> > >> >> >> >> > > >as
> > > >>> > >> >> >> >> > > >we already have close() so having a magical
> > constant
> > > >>>for
> > > >>> > >> >>that is
> > > >>> > >> >> >> >> > > >redundant.
> > > >>> > >> >> >> >> > > >
> > > >>> > >> >> >> >> > > >Calling close() from the I/O thread was already
> > > >>>possible
> > > >>> > >>and
> > > >>> > >> >> >>would
> > > >>> > >> >> >> >> block
> > > >>> > >> >> >> >> > > >indefinitely. I think trying to silently change
> > the
> > > >>> > >>behavior
> > > >>> > >> >>is
> > > >>> > >> >> >> >> probably
> > > >>> > >> >> >> >> > > >not right. I.e. if the user calls close() in the
> > > >>> callback
> > > >>> > >> >>there
> > > >>> > >> >> >>is
> > > >>> > >> >> >> >> > > >actually
> > > >>> > >> >> >> >> > > >some misunderstanding and they need to think more,
> > > >>> > >>silently
> > > >>> > >> >> >>making
> > > >>> > >> >> >> >> this
> > > >>> > >> >> >> >> > > >not
> > > >>> > >> >> >> >> > > >block will hide the problem from them which is the
> > > >>> > >>opposite
> > > >>> > >> >>of
> > > >>> > >> >> >> >>what we
> > > >>> > >> >> >> >> > > >want.
> > > >>> > >> >> >> >> > > >
> > > >>> > >> >> >> >> > > >-Jay
> > > >>> > >> >> >> >> > > >
> > > >>> > >> >> >> >> > > >On Thu, Mar 12, 2015 at 1:49 AM, Jiangjie Qin
> > > >>> > >> >> >> >> <j...@linkedin.com.invalid
> > > >>> > >> >> >> >> > >
> > > >>> > >> >> >> >> > > >wrote:
> > > >>> > >> >> >> >> > > >
> > > >>> > >> >> >> >> > > >> Hey Joe & Jay,
> > > >>> > >> >> >> >> > > >>
> > > >>> > >> >> >> >> > > >> Thanks for the comments on the voting thread.
> > > >>>Since it
> > > >>> > >> >>seems
> > > >>> > >> >> >>we
> > > >>> > >> >> >> >> > probably
> > > >>> > >> >> >> >> > > >> will have more discussion on this, I am just
> > > >>>replying
> > > >>> > >>from
> > > >>> > >> >>the
> > > >>> > >> >> >> >> > > >>discussion
> > > >>> > >> >> >> >> > > >> thread here.
> > > >>> > >> >> >> >> > > >> I’ve updated the KIP page to make it less like
> > > >>> > >>half-baked,
> > > >>> > >> >> >> >>apologize
> > > >>> > >> >> >> >> > for
> > > >>> > >> >> >> >> > > >> the rush...
> > > >>> > >> >> >> >> > > >>
> > > >>> > >> >> >> >> > > >> The contract in current KIP is:
> > > >>> > >> >> >> >> > > >> 1. close() - wait until all requests either
> > are
> > > >>>sent
> > > >>> > >>or
> > > >>> > >> >> >>reach
> > > >>> > >> >> >> >> > request
> > > >>> > >> >> >> >> > > >> timeout.
> > > >>> > >> >> >> >> > > >> 2. close(-1, TimeUnit.MILLISECONDS) - close
> > > >>> > >>immediately
> > > >>> > >> >> >> >> > > >> 3. close(0, TimeUnit.MILLISECONDS) -
> > equivalent
> > > >>>to
> > > >>> > >> >>close(),
> > > >>> > >> >> >> >>i.e.
> > > >>> > >> >> >> >> > Wait
> > > >>> > >> >> >> >> > > >> until all requests are sent or reach request
> > > >>>timeout
> > > >>> > >> >> >> >> > > >> 4. close(5, TimeUnit.MILLISECONDS) - try the
> > > >>>best to
> > > >>> > >> >>finish
> > > >>> > >> >> >> >> sending
> > > >>> > >> >> >> >> > > >>in 5
> > > >>> > >> >> >> >> > > >> milliseconds, if something went wrong, just
> > > >>>shutdown
> > > >>> the
> > > >>> > >> >> >>producer
> > > >>> > >> >> >> >> > > >>anyway,
> > > >>> > >> >> >> >> > > >> my callback will handle the failures.
> > > >>> > >> >> >> >> > > >>
> > > >>> > >> >> >> >> > > >> About how we define what timeout value stands
> > for,
> > > >>>I
> > > >>> > >> >>actually
> > > >>> > >> >> >> >> > struggled
> > > >>> > >> >> >> >> > > >>a
> > > >>> > >> >> >> >> > > >> little bit when wrote the patch. Intuitively,
> > > >>>close(0)
> > > >>> > >> >>should
> > > >>> > >> >> >> >>mean
> > > >>> > >> >> >> >> > > >> immediately, however it seems that all the
> > > >>>existing
> > > >>> java
> > > >>> > >> >>class
> > > >>> > >> >> >> >>have
> > > >>> > >> >> >> >> > this
> > > >>> > >> >> >> >> > > >> convention of timeout=0 means no timeout or
> > never
> > > >>> > >>timeout
> > > >>> > >> >> >> >> > > >>(Thread.join(0),
> > > >>> > >> >> >> >> > > >> Object.wait(0), etc.) So here the dilemma is
> > > >>>either we
> > > >>> > >> >>follow
> > > >>> > >> >> >>the
> > > >>> > >> >> >> >> > > >> intuition or we follow the convention. What I
> > > >>>chose is
> > > >>> > >>to
> > > >>> > >> >> >>follow
> > > >>> > >> >> >> >>the
> > > >>> > >> >> >> >> > > >> convention but document the interface to let
> > user
> > > >>>be
> > > >>> > >>aware
> > > >>> > >> >>of
> > > >>> > >> >> >>the
> > > >>> > >> >> >> >> > usage.
> > > >>> > >> >> >> >> > > >> The reason is that I think producer.close() is a
> > > >>> public
> > > >>> > >> >> >> >>interface so
> > > >>> > >> >> >> >> > it
> > > >>> > >> >> >> >> > > >> might be better to follow java convention.
> > Whereas
> > > >>> > >> >>selector is
> > > >>> > >> >> >> >>not a
> > > >>> > >> >> >> >> > > >> public interface that used by user, so as long
> > as
> > > >>>it
> > > >>> > >>makes
> > > >>> > >> >> >>sense
> > > >>> > >> >> >> >>to
> > > >>> > >> >> >> >> > us,
> > > >>> > >> >> >> >> > > >>it
> > > >>> > >> >> >> >> > > >> is less a problem to be different from java
> > > >>> convention.
> > > >>> > >> >>That
> > > >>> > >> >> >>said
> > > >>> > >> >> >> >> > since
> > > >>> > >> >> >> >> > > >> consumer.poll(timeout) is also a public
> > interface,
> > > >>>I
> > > >>> > >>think
> > > >>> > >> >>it
> > > >>> > >> >> >> >>also
> > > >>> > >> >> >> >> > makes
> > > >>> > >> >> >> >> > > >> sense to make producer.close() to have the same
> > > >>> > >>definition
> > > >>> > >> >>of
> > > >>> > >> >> >> >> > > >> consumer.poll(timeout).
> > > >>> > >> >> >> >> > > >>
> > > >>> > >> >> >> >> > > >> The main argument for keeping a timeout in close
> > > >>>would
> > > >>> > >>be
> > > >>> > >> >> >> >>separating
> > > >>> > >> >> >> >> > the
> > > >>> > >> >> >> >> > > >> close timeout from request timeout, which
> > probably
> > > >>> makes
> > > >>> > >> >> >>sense. I
> > > >>> > >> >> >> >> > would
> > > >>> > >> >> >> >> > > >> guess typically the request timeout would be
> > long
> > > >>> (e.g.
> > > >>> > >>60
> > > >>> > >> >> >> >>seconds)
> > > >>> > >> >> >> >> > > >> because we might want to consider retries with
> > > >>>back
> > > >>> off
> > > >>> > >> >>time.
> > > >>> > >> >> >>If
> > > >>> > >> >> >> >>we
> > > >>> > >> >> >> >> > have
> > > >>> > >> >> >> >> > > >> multiple batches in accumulator, in worst case
> > > >>>that
> > > >>> > >>could
> > > >>> > >> >>take
> > > >>> > >> >> >> >>up to
> > > >>> > >> >> >> >> > > >> several minutes to complete all the requests.
> > But
> > > >>>when
> > > >>> > >>we
> > > >>> > >> >> >>close a
> > > >>> > >> >> >> >> > > >> producer, we might not want to wait for that
> > long
> > > >>>as
> > > >>> it
> > > >>> > >> >>might
> > > >>> > >> >> >> >>cause
> > > >>> > >> >> >> >> > some
> > > >>> > >> >> >> >> > > >> other problem like deployment tool timeout.
> > > >>> > >> >> >> >> > > >>
> > > >>> > >> >> >> >> > > >> There is also a subtle difference between
> > > >>> close(timeout)
> > > >>> > >> >>and
> > > >>> > >> >> >> >> > > >> flush(timeout). The only purpose for flush() is
> > to
> > > >>> write
> > > >>> > >> >>data
> > > >>> > >> >> >>to
> > > >>> > >> >> >> >>the
> > > >>> > >> >> >> >> > > >> broker, so it makes perfect sense to wait until
> > > >>> request
> > > >>> > >> >> >>timeout.
> > > >>> > >> >> >> >>I
> > > >>> > >> >> >> >> > think
> > > >>> > >> >> >> >> > > >> that is why flush(timeout) looks strange. On the
> > > >>>other
> > > >>> > >> >>hand,
> > > >>> > >> >> >>the
> > > >>> > >> >> >> >>top
> > > >>> > >> >> >> >> > > >> priority for close() is to close the producer
> > > >>>rather
> > > >>> > >>than
> > > >>> > >> >> >>flush()
> > > >>> > >> >> >> >> > data,
> > > >>> > >> >> >> >> > > >>so
> > > >>> > >> >> >> >> > > >> close(timeout) gives guarantee on bounded
> > waiting
> > > >>>for
> > > >>> > >>its
> > > >>> > >> >>main
> > > >>> > >> >> >> >>job.
> > > >>> > >> >> >> >> > > >>
> > > >>> > >> >> >> >> > > >> Sorry for the confusion about forceClose flag.
> > It
> > > >>>is
> > > >>> > >>not a
> > > >>> > >> >> >>public
> > > >>> > >> >> >> >> > > >> interface. I mentioned it in Proposed Changes
> > > >>>section
> > > >>> > >> >>which I
> > > >>> > >> >> >> >> thought
> > > >>> > >> >> >> >> > > >>was
> > > >>> > >> >> >> >> > > >> supposed to provide implementation details.
> > > >>> > >> >> >> >> > > >>
> > > >>> > >> >> >> >> > > >> Thanks again for all the comments and
> > suggestions!
> > > >>> > >> >> >> >> > > >>
> > > >>> > >> >> >> >> > > >> Jiangjie (Becket) Qin
> > > >>> > >> >> >> >> > > >>
> > > >>> > >> >> >> >> > > >> On 3/10/15, 8:57 PM, "Jiangjie Qin" <
> > > >>> j...@linkedin.com>
> > > >>> > >> >> wrote:
> > > >>> > >> >> >> >> > > >>
> > > >>> > >> >> >> >> > > >> >The KIP page has been updated per Jay¹s
> > comments.
> > > >>> > >> >> >> >> > > >> >I¹d like to initiate the voting process if no
> > > >>>further
> > > >>> > >> >> >>comments
> > > >>> > >> >> >> >>are
> > > >>> > >> >> >> >> > > >> >received by tomorrow.
> > > >>> > >> >> >> >> > > >> >
> > > >>> > >> >> >> >> > > >> >Jiangjie (Becket) Qin
> > > >>> > >> >> >> >> > > >> >
> > > >>> > >> >> >> >> > > >> >On 3/8/15, 9:45 AM, "Jay Kreps"
> > > >>><jay.kr...@gmail.com
> > > >>> >
> > > >>> > >> >>wrote:
> > > >>> > >> >> >> >> > > >> >
> > > >>> > >> >> >> >> > > >> >>Hey Jiangjie,
> > > >>> > >> >> >> >> > > >> >>
> > > >>> > >> >> >> >> > > >> >>Can you capture the full motivation and use
> > > >>>cases
> > > >>> for
> > > >>> > >>the
> > > >>> > >> >> >> >>feature?
> > > >>> > >> >> >> >> > > >>This
> > > >>> > >> >> >> >> > > >> >>mentions your interest in having a way of
> > > >>>aborting
> > > >>> > >>from
> > > >>> > >> >> >>inside
> > > >>> > >> >> >> >>the
> > > >>> > >> >> >> >> > > >> >>Callback. But it doesn't really explain that
> > > >>>usage
> > > >>> or
> > > >>> > >>why
> > > >>> > >> >> >>other
> > > >>> > >> >> >> >> > people
> > > >>> > >> >> >> >> > > >> >>would want to do that. It also doesn't list
> > the
> > > >>> > >>primary
> > > >>> > >> >>use
> > > >>> > >> >> >> >>case
> > > >>> > >> >> >> >> for
> > > >>> > >> >> >> >> > > >> >>having
> > > >>> > >> >> >> >> > > >> >>close with a bounded timeout which was to
> > avoid
> > > >>> > >>blocking
> > > >>> > >> >>too
> > > >>> > >> >> >> >>long
> > > >>> > >> >> >> >> on
> > > >>> > >> >> >> >> > > >> >>shutdown.
> > > >>> > >> >> >> >> > > >> >>
> > > >>> > >> >> >> >> > > >> >>-Jay
> > > >>> > >> >> >> >> > > >> >>
> > > >>> > >> >> >> >> > > >> >>
> > > >>> > >> >> >> >> > > >> >>
> > > >>> > >> >> >> >> > > >> >>On Sat, Mar 7, 2015 at 12:25 PM, Jiangjie Qin
> > > >>> > >> >> >> >> > > >><j...@linkedin.com.invalid
> > > >>> > >> >> >> >> > > >> >
> > > >>> > >> >> >> >> > > >> >>wrote:
> > > >>> > >> >> >> >> > > >> >>
> > > >>> > >> >> >> >> > > >> >>> Hi,
> > > >>> > >> >> >> >> > > >> >>>
> > > >>> > >> >> >> >> > > >> >>> I just created a KIP for adding a
> > > >>>close(timeout)
> > > >>> to
> > > >>> > >>new
> > > >>> > >> >> >> >> producer.
> > > >>> > >> >> >> >> > > >>Most
> > > >>> > >> >> >> >> > > >> >>>of
> > > >>> > >> >> >> >> > > >> >>> the previous discussions are in KAFKA-1660
> > > >>>where
> > > >>> > >>Parth
> > > >>> > >> >> >> >> Brahmbhatt
> > > >>> > >> >> >> >> > > >>has
> > > >>> > >> >> >> >> > > >> >>> already done a lot of work.
> > > >>> > >> >> >> >> > > >> >>> Since this is an interface change so we are
> > > >>>going
> > > >>> > >> >>through
> > > >>> > >> >> >>the
> > > >>> > >> >> >> >> KIP
> > > >>> > >> >> >> >> > > >> >>>process.
> > > >>> > >> >> >> >> > > >> >>> Here is the KIP link:
> > > >>> > >> >> >> >> > > >> >>>
> > > >>> > >> >> >> >> > > >> >>>
> > > >>> > >> >> >> >> > > >>
> > > >>> > >> >> >> >> > >
> > > >>> > >> >> >> >>
> > > >>> > >> >> >>
> > > >>> > >> >>
> > > >>> > >>
> > > >>> >
> > > >>>
> > > https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=5373978
> > > >>> > >> >> >> >> > > >> >>>2
> > > >>> > >> >> >> >> > > >> >>>
> > > >>> > >> >> >> >> > > >> >>> Thanks.
> > > >>> > >> >> >> >> > > >> >>>
> > > >>> > >> >> >> >> > > >> >>> Jiangjie (Becket) Qin
> > > >>> > >> >> >> >> > > >> >>>
> > > >>> > >> >> >> >> > > >> >
> > > >>> > >> >> >> >> > > >>
> > > >>> > >> >> >> >> > > >>
> > > >>> > >> >> >> >> > >
> > > >>> > >> >> >> >> > >
> > > >>> > >> >> >> >> >
> > > >>> > >> >> >> >>
> > > >>> > >> >> >> >>
> > > >>> > >> >> >> >>
> > > >>> > >> >> >> >> --
> > > >>> > >> >> >> >> Thanks,
> > > >>> > >> >> >> >> Neha
> > > >>> > >> >> >> >>
> > > >>> > >> >> >> >
> > > >>> > >> >> >> >
> > > >>> > >> >> >> >
> > > >>> > >> >> >> >--
> > > >>> > >> >> >> >-- Guozhang
> > > >>> > >> >> >>
> > > >>> > >> >> >>
> > > >>> > >> >> >
> > > >>> > >> >> >
> > > >>> > >> >> >--
> > > >>> > >> >> >-- Guozhang
> > > >>> > >> >>
> > > >>> > >> >>
> > > >>> > >> >
> > > >>> > >> >
> > > >>> > >> >--
> > > >>> > >> >-- Guozhang
> > > >>> > >>
> > > >>> > >>
> > > >>> >
> > > >>> >
> > > >>>
> > > >>
> > > >>
> > > >>
> > > >>--
> > > >>-- Guozhang
> > > >
> > >
> > >
> >
>
>
>
> --
> Thanks,
> Neha
