Hi Alieh and Justine,
I'm concerned that we're settling on a definition of "poison pill" that's
easiest to tackle right now but may lead to shortcomings down the road. I
understand the relationship between this KIP and KAFKA-9279, and I can
totally get behind the desire to keep things small, focused, and simple in
the name of avoiding bugs. However, what I don't think is clear at all is
what the "specific circumstances" are that Justine mentioned. I had a
drastically different idea of what the intended behavioral change would be
before looking at the draft PR.
I would like 1) for us to be clearer about the categories of errors that we
want to cover with this new API (especially since we'll have to find a
clear, succinct way to document this for users), and 2) to make sure that
if we do try to expand this API in the future, that we won't be painted
into a corner.
For item 1, hopefully we can agree that the language in the KIP
for IGNORE_SEND_ERRORS ("The records causing irrecoverable errors are
excluded from the batch and the transaction is committed successfully.") is
pretty vague. If we start using the phrase "poison pill record" that could
help, but IMO more detail would still be needed. We know that we want to
include records that are so large that they can be immediately rejected by
the producer. But there are other cases that users might expect to be
handled. Does a record qualify as a poison pill if it targets a topic that
doesn't exist? Or if it targets a topic that the producer principal lacks
ACLs for? What if it fails broker-side validation (e.g., has a null key for
a compacted topic)?
For item 2, this really depends on how narrow the scope of what we're doing
right now is. If we only handle a subset of the examples I laid out above
that could possibly be considered poison pills with this KIP, do we want to
lock ourselves in to never addressing more in the future, or can we choose
an API (probably just enum names would be the only important decision here)
that leaves room for more later?
Best,
Chris
On Tue, Jul 2, 2024 at 12:28 PM Justine Olshan <jols...@confluent.io.invalid>
wrote:
> Chris and Alieh,
>
> My understanding is that this KIP is really only trying to solve an issue
> of a "poison pill" record that fails send().
> We've talked a lot about having a generic framework for all errors, but I
> don't think that is what this KIP is trying to do. Essentially the request
> is to undo the change from KAFKA-9279
> <https://issues.apache.org/jira/browse/KAFKA-9279> but under specific
> circumstances that are controlled. I really am concerned about opening new
> avenues for bugs with EOS and hesitate to handle any other types of errors.
> I think if we all agree on the problem that we are trying to solve, it is
> easier to agree on solutions.
>
> Justine
>
> On Mon, Jul 1, 2024 at 2:20 AM Alieh Saeedi <asae...@confluent.io.invalid>
> wrote:
>
> > Hi Matthias,
> > Thanks for the valid points you mentioned. I updated the KIP and the PR
> > with:
> > 1) mentioning that the new overloaded `send` throws
> `IllegalStateException`
> > if the user tries to ignore `send()` errors outside of a transaction.
> > 2) the default implementation in `Producer` interface throws an
> > `UnsupportedOperationException`
> >
> > Hi Chris,
> > Thanks for the feedback. I tried to clarify the points you listed:
> > -------> we've narrowed the scope from any error that might take place
> with
> > producing a record to Kafka, to only the ones that are thrown directly
> from
> > Producer::send;
> >
> > From the very beginning and even since KIP-1038, the main purpose was to
> > have "more flexibility," or, in other words, "giving the user the
> > authority" to handle some specific exceptions thrown from the `Producer`.
> > Due to the specific cases we had in mind, KIP-1038 was discarded and we
> > decided to not define a `CustomExceptionHandler` for `Producer` and
> instead
> > treat the `send` failures in a different way. The main issue is that
> `send`
> > makes a transition to error state, which is undoable. In fact, one single
> > poison pill record makes the whole batch fail. The former suggestions
> that
> > you agreed with have been all about un-doing this transition in `flush`
> or
> > `commit`. The new suggestion is to un-do (or better, NOT do) in `send`
> due
> > to the reasons listed in the discussions above.
> > Moreover, I would say that having such a large scope as you mentioned is
> > impossible. In the best case, we may have control over the `Producer`.
> What
> > shall we do with the broker? The `any error that might take place with
> > producing a record to Kafka` is too much, I think.
> >
> > -------> is this all we want to handle, and will it prevent us from
> > handling more in the future in an intuitive way?
> >
> > I think yes. This is all we want. Other sorts of errors such as having
> > problem with partition addition, producer fenced exception, etc seem to
> be
> > more serious issues. The intention was to handle problems created by
> > (maybe) a single poison pill record. BTW, I do not see any obstacles to
> > future changes.
> >
> > Bests,
> > Alieh
> >
> > On Sat, Jun 29, 2024 at 3:03 AM Chris Egerton <chr...@aiven.io.invalid>
> > wrote:
> >
> > > Ah, sorry--spoke too soon. The PR doesn't show that errors thrown from
> > > Producer::send are handled, but instead, ApiException instances that
> are
> > > caught inside KafkaProducer::doSend and are handled by returning an
> > > already-failed future are. I think the same question still applies (is
> > this
> > > all we want to handle, and will it prevent us from handling more in the
> > > future in an intuitive way), though.
> > >
> > > On Fri, Jun 28, 2024 at 8:57 PM Chris Egerton <chr...@aiven.io> wrote:
> > >
> > > > Hi Alieh,
> > > >
> > > > This KIP has evolved a lot since I last looked at it, but the changes
> > > seem
> > > > well thought-out both in semantics and API. One clarifying question I
> > > have
> > > > is that it looks based on the draft PR that we've narrowed the scope
> > from
> > > > any error that might take place with producing a record to Kafka, to
> > only
> > > > the ones that are thrown directly from Producer::send; is that the
> > > intended
> > > > behavior here? And if so, do you have thoughts on how we might
> design a
> > > > follow-up KIP that would catch all errors (including ones reported
> > > > asynchronously instead of synchronously)? I'd like it if we could
> leave
> > > the
> > > > door open for that without painting ourselves into too much of a
> corner
> > > > with the API design for this KIP.
> > > >
> > > > Cheers,
> > > >
> > > > Chris
> > > >
> > > > On Fri, Jun 28, 2024 at 6:31 PM Matthias J. Sax <mj...@apache.org>
> > > wrote:
> > > >
> > > >> Thanks Alieh,
> > > >>
> > > >> it seems this KIP can just pick between a couple of tradeoffs.
> Adding
> > an
> > > >> overloaded `send()` as the KIP propose makes sense to me and seems
> to
> > > >> provides the cleanest solution compare to there options we
> discussed.
> > > >>
> > > >> Given the explicit name of the passed-in option that highlights that
> > the
> > > >> option is for TX only make is pretty clear and avoids the issue of
> > > >> `flush()` ambiguity.
> > > >>
> > > >>
> > > >> Nit: We should make clear on the KIP though, that the new `send()`
> > > >> overload would throw an `IllegalStateException` if TX are not used
> > > >> (similar to other TX methods like initTx(), etc)
> > > >>
> > > >>
> > > >> About the `Producer` interface, I am not sure how this was done in
> the
> > > >> past (eg, KIP-266 added `Consumer.poll(Duration)` w/o a default
> > > >> implementation), if we need a default implementation for backward
> > > >> compatibility or not? If we do want to add one, I think it would be
> > > >> appropriate to throw an `UnsupportedOperationException` by default,
> > > >> instead of just keeping the default impl empty?
> > > >>
> > > >>
> > > >> My points are rather minor, and should not block this KIP though.
> > > >> Overall LGTM.
> > > >>
> > > >>
> > > >>
> > > >> -Matthias
> > > >>
> > > >> On 6/27/24 1:28 PM, Alieh Saeedi wrote:
> > > >> > Hi Justine,
> > > >> >
> > > >> > Thanks for the suggestion.
> > > >> > Making applications to validate every single record is not the
> best
> > > way,
> > > >> > from an efficiency point of view.
> > > >> > Moreover, between changing the behavior of the Producer in `send`
> > and
> > > >> > `commitTnx`, the former seems more reasonable and clean.
> > > >> >
> > > >> > Bests,
> > > >> > Alieh
> > > >> >
> > > >> > On Thu, Jun 27, 2024 at 8:14 PM Justine Olshan
> > > >> <jols...@confluent.io.invalid>
> > > >> > wrote:
> > > >> >
> > > >> >> Hey Alieh,
> > > >> >>
> > > >> >> I see there are two options now. So folks will be discussing the
> > > >> approaches
> > > >> >> and deciding the best way forward before we vote?
> > > >> >> I do think there could be a problem with the approach on commit
> if
> > we
> > > >> get
> > > >> >> stuck on an earlier error and have more records (potentially on
> new
> > > >> >> partitions) to commit as the current PR is implemented.
> > > >> >>
> > > >> >> I guess this takes us back to the question of whether the error
> > > should
> > > >> be
> > > >> >> cleared on send.
> > > >> >>
> > > >> >> (And I guess at the back of my mind, I'm wondering if there is a
> > way
> > > >> we can
> > > >> >> validate the "posion pill" records application side before we
> even
> > > try
> > > >> to
> > > >> >> send them)
> > > >> >>
> > > >> >> Justine
> > > >> >>
> > > >> >> On Wed, Jun 26, 2024 at 4:38 PM Alieh Saeedi
> > > >> <asae...@confluent.io.invalid
> > > >> >>>
> > > >> >> wrote:
> > > >> >>
> > > >> >>> Hi Justine,
> > > >> >>>
> > > >> >>> I did not update the KIP with `TxnSendOption` since I thought
> it'd
> > > be
> > > >> >>> better discussed here beforehand.
> > > >> >>> right now, there are 2 PRs:
> > > >> >>> - the PR that implements the current version of the KIP:
> > > >> >>> https://github.com/apache/kafka/pull/16332
> > > >> >>> - the POC PR that clarifies the `TxnSendOption`:
> > > >> >>> https://github.com/apache/kafka/pull/16465
> > > >> >>>
> > > >> >>> Bests,
> > > >> >>> Alieh
> > > >> >>>
> > > >> >>> On Thu, Jun 27, 2024 at 12:42 AM Justine Olshan
> > > >> >>> <jols...@confluent.io.invalid> wrote:
> > > >> >>>
> > > >> >>>> Hey Alieh,
> > > >> >>>>
> > > >> >>>> I think I am a little confused. Are the 3 points above
> addressed
> > by
> > > >> the
> > > >> >>> KIP
> > > >> >>>> or did something change? The PR seems to not include this
> change
> > > and
> > > >> >>> still
> > > >> >>>> has the CommitOption as well.
> > > >> >>>>
> > > >> >>>> Thanks,
> > > >> >>>> Justine
> > > >> >>>>
> > > >> >>>> On Wed, Jun 26, 2024 at 2:15 PM Alieh Saeedi
> > > >> >>> <asae...@confluent.io.invalid
> > > >> >>>>>
> > > >> >>>> wrote:
> > > >> >>>>
> > > >> >>>>> Hi all,
> > > >> >>>>>
> > > >> >>>>>
> > > >> >>>>> Looking at the PR <https://github.com/apache/kafka/pull/16332
> >
> > > >> >>>>> corresponding to the KIP, there are some points worthy of
> > mention:
> > > >> >>>>>
> > > >> >>>>>
> > > >> >>>>> 1) clearing the error ends up dirty/messy code in
> > > >> >> `TransactionManager`.
> > > >> >>>>>
> > > >> >>>>> 2) By clearing the error, we are actually doing an illegal
> > > >> transition
> > > >> >>>> from
> > > >> >>>>> `ABORTABLE_ERROR` to `IN_TRANSACTION` which is conceptually
> not
> > > >> >>>> acceptable.
> > > >> >>>>> This can be the root cause of some issues, with perhaps
> further
> > > >> >> future
> > > >> >>>>> changes by others.
> > > >> >>>>>
> > > >> >>>>> 3) If the poison pill record `r1` causes a transition to the
> > error
> > > >> >>> state
> > > >> >>>>> and then the next record `r2` requires adding a partition to
> the
> > > >> >>>>> transaction, the action fails due to being in the error state.
> > In
> > > >> >> this
> > > >> >>>>> case, clearing errors during `commitTnx(CLEAR_SEND_ERROR)` is
> > too
> > > >> >> late.
> > > >> >>>>> However, this case can NOT be the main concern as soon as
> > KIP-890
> > > is
> > > >> >>>> fully
> > > >> >>>>> implemented.
> > > >> >>>>>
> > > >> >>>>>
> > > >> >>>>> My suggestion is to solve the problem where it arises. If the
> > > >> >>> transition
> > > >> >>>> to
> > > >> >>>>> the error state does not happen during `send()`, we do not
> need
> > to
> > > >> >>> clear
> > > >> >>>>> the error later. Therefore, instead of `CommitOption`, we can
> > > define
> > > >> >> a
> > > >> >>>>> `TxnSendOption` and prevent the `send()` method from going to
> > the
> > > >> >> error
> > > >> >>>>> state in case 1) we're in a transaction and 2) the user asked
> > for
> > > >> >>>>> IGONRE_SEND_ERRORS. For more clarity, you can take a look at
> the
> > > POC
> > > >> >> PR
> > > >> >>>>> <https://github.com/apache/kafka/pull/16465>.
> > > >> >>>>>
> > > >> >>>>> Cheers,
> > > >> >>>>> Alieh
> > > >> >>>>>
> > > >> >>>>
> > > >> >>>
> > > >> >>
> > > >> >
> > > >>
> > > >
> > >
> >
>
