hi All This KIP is based on our use case where an edge application with many sensors wants to use a single producer to deliver ‘few but varied’ records with different acks settings. The reason for using a single producer is to minimize resource usage on edge devices with limited hardware capabilities. Currently, we use a producer pool to handle different acks values, which requires 3x producer instances. Additionally, this approach creates many idle producers if a sensor with a specific acks setting has no data for a while.
I love David’s suggestion since the acks configuration is closely related to the topic. Maybe we can introduce an optional configuration in the producer to define topic-level acks, with the existing acks being the default for all topics. This approach is not only simple but also easy to understand and implement. Best, Chia-Ping On 2024/11/13 16:04:24 Andrew Schofield wrote: > Hi TaiJuWu, > I've been thinking for a while about this KIP before jumping into the > discussion. > > I'm afraid that I don't think the approach in the KIP is the best, given the > design > of the Kafka protocol in this area. Essentially, each Produce request contains > the acks value at the top level, and may contain records for many topics or > partitions. My point is that batching occurs at the level of a Produce > request, > so changing the acks value between records will require a new Produce request > to be sent. There would likely be an efficiency penalty if this feature was > used > heavily with the acks changing record by record. > > I can see that potentially an application might want different ack levels for > different topics, but I would be surprised if they use different ack levels > within > the same topic. Maybe David's suggestion of defining the acks per topic > would be enough. What do you think? > > Thanks, > Andrew > ________________________________________ > From: David Jacot <dja...@confluent.io.INVALID> > Sent: 13 November 2024 15:31 > To: dev@kafka.apache.org <dev@kafka.apache.org> > Subject: Re: [DISCUSS]KIP-1107: Adding record-level acks for producers > > Hi TaiJuWu, > > Thanks for the KIP. > > The motivation is not clear to me. Could you please elaborate a bit more on > it? > > My concern is that it adds a lot of complexity and the added value seems to > be low. Moreover, it will make reasoning about an application from the > server side more difficult because we can no longer assume that it writes > with the ack based on the config. Another issue is about the batching, how > do you plan to handle batches mixing records with different acks? > > An alternative approach may be to define the ack per topic. We could even > think about defining it on the server side as a topic config. I haven't > really thought about it but it may be something to explore a bit more. > > Best, > David > > On Wed, Nov 13, 2024 at 3:56 PM Frédérik Rouleau > <froul...@confluent.io.invalid> wrote: > > > Hi TaiJuWu, > > > > I find this adding lot's of complexity and I am still not convinced by the > > added value. IMO creating a producer instance per ack level is not > > problematic and the behavior is clear for developers. What would be the > > added value of the proposed change ? > > > > Regards, > > > > > > On Wed, Nov 6, 2024 at 7:50 AM TaiJu Wu <tjwu1...@gmail.com> wrote: > > > > > Hi Fred and Greg, > > > > > > Thanks for your feedback and it really not straightforward but > > interesting! > > > There are some behavior I expect. > > > > > > The current producer uses the *RecordAccumulator* to gather records, and > > > the sender thread sends them in batches. We can track each record’s > > > acknowledgment setting as it appends to the *RecordAccumulator*, allowing > > > the *sender *to group batches by acknowledgment levels and topicPartition > > > when processing. > > > > > > Regarding the statement, "Callbacks for records being sent to the same > > > partition are guaranteed to execute in order," this is ensured when > > > *max.inflight.request > > > *is set to 1. We can send records with different acknowledgment levels in > > > the order of acks-0, acks=1, acks=-1. Since we need to send batches with > > > different acknowledgment levels batches to the broker, the callback will > > > execute after each request is completed. > > > > > > In response to, "If so, are low-acks records subject to head-of-line > > > blocking from high-acks records?," I believe an additional configuration > > is > > > necessary to control this behavior. We could allow records to be either > > > sync or async, though the callback would still execute after each batch > > > with varying acknowledgment levels completes. To measure behavior across > > > acknowledgment levels, we could also include acks in > > *ProducerIntercepor*. > > > > > > Furthermore, before this KIP, a producer could only include one acks > > level > > > so sequence is premised. However, with this change, we can *ONLY* > > guarantee > > > the sequence within records of the same acknowledgment level because we > > may > > > send up to three separate requests to brokers. > > > Best, > > > TaiJuWu > > > > > > > > > TaiJu Wu <tjwu1...@gmail.com> 於 2024年11月6日 週三 上午10:01寫道： > > > > > > > Hi Fred and Greg, > > > > > > > > Apologies for the delayed response. > > > > Yes, you’re correct. > > > > I’ll outline the behavior I expect. > > > > > > > > Thanks for your feedback! > > > > > > > > Best, > > > > TaiJuWu > > > > > > > > > > > > Greg Harris <greg.har...@aiven.io.invalid> 於 2024年11月6日 週三 上午9:48寫道： > > > > > > > >> Hi TaiJuWu, > > > >> > > > >> Thanks for the KIP! > > > >> > > > >> Can you explain in the KIP about the behavior when the number of acks > > is > > > >> different for individual records? I think the current description > > using > > > >> the > > > >> word "straightforward" does little to explain that, and may actually > > be > > > >> hiding some complexity. > > > >> > > > >> For example, the send() javadoc contains this: "Callbacks for records > > > >> being > > > >> sent to the same partition are guaranteed to execute in order." Is > > this > > > >> still true when acks vary for records within the same partition? > > > >> If so, are low-acks records subject to head-of-line-blocking from > > > >> high-acks > > > >> records? It seems to me that this feature is useful when acks is > > > specified > > > >> per-topic, but introduces a lot of edge cases that are underspecified. > > > >> > > > >> Thanks, > > > >> Greg > > > >> > > > >> > > > >> On Tue, Nov 5, 2024 at 4:52 PM TaiJu Wu <tjwu1...@gmail.com> wrote: > > > >> > > > >> > Hi Chia-Ping, > > > >> > > > > >> > Thanks for your feedback. > > > >> > I have updated KIP based on your suggestions. > > > >> > > > > >> > Best, > > > >> > Stanley > > > >> > > > > >> > Chia-Ping Tsai <chia7...@apache.org> 於 2024年11月5日 週二 下午4:41寫道： > > > >> > > > > >> > > hi TaiJuWu, > > > >> > > > > > >> > > Q0: Could you please add getter (Short acks()) to "public > > interface" > > > >> > > section? > > > >> > > > > > >> > > Q1: Could you please add RPC json reference to prove "been > > available > > > >> at > > > >> > > the RPC-level," > > > >> > > > > > >> > > Q2: Could you please add link to producer docs to prove "share a > > > >> single > > > >> > > producer instance across multiple threads" > > > >> > > > > > >> > > Thanks, > > > >> > > Chia-Ping > > > >> > > > > > >> > > On 2024/11/05 01:28:36 吳岱儒 wrote: > > > >> > > > Hi all, > > > >> > > > > > > >> > > > I open a KIP-1107: Adding record-level acks for producers > > > >> > > > < > > > >> > > > > > >> > > > > >> > > > > > https://cwiki.apache.org/confluence/display/KAFKA/KIP-1107%3A++Adding+record-level+acks+for+producers > > > >> > > > > > > >> > > > to > > > >> > > > reduce the limitation associated with reusing KafkaProducer. > > > >> > > > > > > >> > > > > > > >> > > > > > >> > > > > >> > > > > > https://cwiki.apache.org/confluence/display/KAFKA/KIP-1107%3A++Adding+record-level+acks+for+producers > > > >> > > > > > > >> > > > Feedbacks and suggestions are welcome. > > > >> > > > > > > >> > > > Thanks, > > > >> > > > TaiJuWu > > > >> > > > > > > >> > > > > > >> > > > > >> > > > > > > > > > >
