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From Jason Gustafson <ja...@confluent.io>
Subject Re: [DISCUSSION] KIP-266: Add TimeoutException to KafkaConsumer#position()
Date Sat, 17 Mar 2018 19:00:25 GMT
Hi Richard,

Thanks for the updates. I'm really glad you picked this up. A couple minor
comments:

1. Can you list the full set of new APIs explicitly in the KIP? Currently I
only see the javadoc for `position()`.

2. We should consider adding `TimeUnit` to the new methods to avoid unit
confusion. I know it's inconsistent with the poll() API, but I think it was
probably a mistake not to include it there, so better not to double down on
that mistake. And note that we do already have `close(long, TimeUnit)`.

Other than that, I think the current KIP seems reasonable.

Thanks,
Jason

On Wed, Mar 14, 2018 at 5:00 PM, Richard Yu <yohan.richard.yu@gmail.com>
wrote:

> Note to all: I have included bounding commitSync() and committed() in this
> KIP.
>
> On Sun, Mar 11, 2018 at 5:05 PM, Richard Yu <yohan.richard.yu@gmail.com>
> wrote:
>
> > Hi all,
> >
> > I updated the KIP where overloading position() is now the favored
> approach.
> > Bounding position() using requestTimeoutMs has been listed as rejected.
> >
> > Any thoughts?
> >
> > On Tue, Mar 6, 2018 at 6:00 PM, Guozhang Wang <wangguoz@gmail.com>
> wrote:
> >
> >> I agree that adding the overloads is most flexible. But going for that
> >> direction we'd do that for all the blocking call that I've listed above,
> >> with this timeout value covering the end-to-end waiting time.
> >>
> >>
> >> Guozhang
> >>
> >> On Tue, Mar 6, 2018 at 10:02 AM, Ted Yu <yuzhihong@gmail.com> wrote:
> >>
> >> > bq. The most flexible option is to add overloads to the consumer
> >> >
> >> > This option is flexible.
> >> >
> >> > Looking at the tail of SPARK-18057, Spark dev voiced the same choice.
> >> >
> >> > +1 for adding overload with timeout parameter.
> >> >
> >> > Cheers
> >> >
> >> > On Mon, Mar 5, 2018 at 2:42 PM, Jason Gustafson <jason@confluent.io>
> >> > wrote:
> >> >
> >> > > @Guozhang I probably have suggested all options at some point or
> >> another,
> >> > > including most recently, the current KIP! I was thinking that
> >> practically
> >> > > speaking, the request timeout defines how long the user is willing
> to
> >> > wait
> >> > > for a response. The consumer doesn't really have a complex send
> >> process
> >> > > like the producer for any of these APIs, so I wasn't sure how much
> >> > benefit
> >> > > there would be from having more granular control over timeouts (in
> the
> >> > end,
> >> > > KIP-91 just adds a single timeout to control the whole send). That
> >> said,
> >> > it
> >> > > might indeed be better to avoid overloading the config as you
> suggest
> >> > since
> >> > > at least it avoids inconsistency with the producer's usage.
> >> > >
> >> > > The most flexible option is to add overloads to the consumer so that
> >> > users
> >> > > can pass the timeout directly. I'm not sure if that is more or less
> >> > > annoying than a new config, but I've found config timeouts a little
> >> > > constraining in practice. For example, I could imagine users wanting
> >> to
> >> > > wait longer for an offset commit operation than a position lookup;
> if
> >> the
> >> > > latter isn't timely, users can just pause the partition and continue
> >> > > fetching on others. If you cannot commit offsets, however, it might
> be
> >> > > safer for an application to wait availability of the coordinator
> than
> >> > > continuing.
> >> > >
> >> > > -Jason
> >> > >
> >> > > On Sun, Mar 4, 2018 at 10:14 PM, Guozhang Wang <wangguoz@gmail.com>
> >> > wrote:
> >> > >
> >> > > > Hello Richard,
> >> > > >
> >> > > > Thanks for the proposed KIP. I have a couple of general comments:
> >> > > >
> >> > > > 1. I'm not sure if piggy-backing the timeout exception on the
> >> > > > existing requestTimeoutMs configured in "request.timeout.ms"
is a
> >> good
> >> > > > idea
> >> > > > since a) it is a general config that applies for all types of
> >> requests,
> >> > > and
> >> > > > 2) using it to cover all the phases of an API call, including
> >> network
> >> > > round
> >> > > > trip and potential metadata refresh is shown to not be a good
> idea,
> >> as
> >> > > > illustrated in KIP-91:
> >> > > >
> >> > > > https://cwiki.apache.org/confluence/display/KAFKA/KIP-
> >> > > > 91+Provide+Intuitive+User+Timeouts+in+The+Producer
> >> > > >
> >> > > > In fact, I think in KAFKA-4879 which is aimed for the same issue
> as
> >> > > > KAFKA-6608,
> >> > > > Jason has suggested we use a new config for the API. Maybe this
> >> would
> >> > be
> >> > > a
> >> > > > more intuitive manner than reusing the request.timeout.ms config.
> >> > > >
> >> > > >
> >> > > > 2. Besides the Consumer.position() call, there are a couple of
> more
> >> > > > blocking calls today that could result in infinite blocking:
> >> > > > Consumer.commitSync() and Consumer.committed(), should they be
> >> > considered
> >> > > > in this KIP as well?
> >> > > >
> >> > > > 3. There are a few other APIs that are today relying on
> >> > > request.timeout.ms
> >> > > > already for breaking the infinite blocking, namely
> >> > > Consumer.partitionFor(),
> >> > > > Consumer.OffsetAndTimestamp() and Consumer.listTopics(), if we
are
> >> > making
> >> > > > the other blocking calls to be relying a new config as suggested
> in
> >> 1)
> >> > > > above, should we also change the semantics of these API functions
> >> for
> >> > > > consistency?
> >> > > >
> >> > > >
> >> > > > Guozhang
> >> > > >
> >> > > >
> >> > > >
> >> > > >
> >> > > > On Sun, Mar 4, 2018 at 11:13 AM, Richard Yu <
> >> > yohan.richard.yu@gmail.com>
> >> > > > wrote:
> >> > > >
> >> > > > > Hi all,
> >> > > > >
> >> > > > > I would like to discuss a potential change which would be
made
> to
> >> > > > > KafkaConsumer:
> >> > > > > https://cwiki.apache.org/confluence/pages/viewpage.
> >> > > > action?pageId=75974886
> >> > > > >
> >> > > > > Thanks,
> >> > > > > Richard Yu
> >> > > > >
> >> > > >
> >> > > >
> >> > > >
> >> > > > --
> >> > > > -- Guozhang
> >> > > >
> >> > >
> >> >
> >>
> >>
> >>
> >> --
> >> -- Guozhang
> >>
> >
> >
>

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