@Qingsheng what are your next steps for this proposal? On Thu, Jan 19, 2023 at 9:14 AM Mason Chen <mas.chen6...@gmail.com> wrote:
> Hi all, > > Sorry to come into the discussion late--I saw the thread earlier. > > I'm also +1 for the change in general. I think most users have this turned > on by default since the overhead is quite low. A default in the two digit > seconds range works well for us. However, I do have two main concerns that > are related, but don't necessarily block this FLIP: > > 1. Timestamp Offset Initializer > > Currently, the timestamp offset initializer defaults the offset reset > strategy to LATEST. This can present some problems if the discovery > interval is set too large since records from new partitions could be > skipped (the set timestamp is not found in Kafka, thus resetting to the > latest). Here is a ticket to allow customizations: > https://issues.apache.org/jira/browse/FLINK-30200 (Qingsheng, you might > remember this from a PR review). Thanks for mentioning this in your FLIP! > > 2. AdminClient Fault Tolerance > > AdminClient, which is used for partition discovery, seems not to handle > Kafka timeouts as robustly as the KafkaConsumer API, and we have noticed > that transient network hiccups cause full job restarts (since the > jobmanager fails) in numerous incidents. Internally, we have introduced an > error handling strategy based on the number of consecutive partition > discovery failures. I'm interested in opening a JIRA ticket to contribute > this feature back to Flink and open making the error handling more > pluggable. What do you think? > > Best, > Mason > > On Sun, Jan 15, 2023 at 11:39 PM Qingsheng Ren <re...@apache.org> wrote: > > > Thanks for the input Becket! > > > > I reorganized this proposal into FLIP-288 [1]. > > > > [1] > > > > > https://cwiki.apache.org/confluence/display/FLINK/FLIP-288%3A+Enable+Dynamic+Partition+Discovery+by+Default+in+Kafka+Source > > > > Best, > > Qingsheng > > > > On Sun, Jan 15, 2023 at 9:18 AM Becket Qin <becket....@gmail.com> wrote: > > > > > Thanks for the proposal, Qingsheng. > > > > > > +1 to enable auto partition discovery by default. Just a reminder, we > > need > > > a FLIP for this. > > > > > > A bit more background on this. > > > > > > Most of the Kafka users simply subscribe to a topic and let the > consumer > > to > > > automatically adapt to partition changes. So enabling auto partition > > > discovery would align with that experience. The counter argument last > > time > > > when I proposed to enable auto partition discovery was mainly due to > the > > > concern from the Flink users. There were arguments that sometimes users > > > don't want the partition changes to get automatically picked up, but > want > > > to do this by restarting the job manually so they can avoid unnoticed > > > changes in the jobs. > > > > > > Given that in the old Flink source, by default the auto partition > > discovery > > > was disabled, and there are use cases from both sides, we simply kept > the > > > behavior unchanged. From the discussion we have here, it looks like > > > enabling auto partition discovery is much preferred. So I think we > should > > > do it. > > > > > > I am not worried about the performance. The new Kafka source will only > > have > > > the SplitEnumerator sending metadata requests when the feature is > > enabled. > > > It is actually much cheaper than the old Kafka source where every > > > subtask does that. > > > > > > Thanks, > > > > > > Jiangjie (Becket) Qin > > > > > > > > > > > > On Sat, Jan 14, 2023 at 11:46 AM Yun Tang <myas...@live.com> wrote: > > > > > > > +1 for this proposal and thanks Qingsheng for driving this. > > > > > > > > Considering the interval, we also set the value as 5min, equivalent > to > > > the > > > > default value of metadata.max.age.ms. > > > > > > > > > > > > Best > > > > Yun Tang > > > > ________________________________ > > > > From: Benchao Li <libenc...@apache.org> > > > > Sent: Friday, January 13, 2023 23:06 > > > > To: dev@flink.apache.org <dev@flink.apache.org> > > > > Subject: Re: [DISCUSS] Enabling dynamic partition discovery by > default > > in > > > > Kafka source > > > > > > > > +1, we've enabled this by default (10mins) in our production for > years. > > > > > > > > Jing Ge <j...@ververica.com.invalid> 于2023年1月13日周五 22:22写道： > > > > > > > > > +1 for the proposal that makes users' daily work easier and > therefore > > > > makes > > > > > Flink more attractive. > > > > > > > > > > Best regards, > > > > > Jing > > > > > > > > > > > > > > > On Fri, Jan 13, 2023 at 11:27 AM Qingsheng Ren <re...@apache.org> > > > wrote: > > > > > > > > > > > Thanks everyone for joining the discussion! > > > > > > > > > > > > @Martijn: > > > > > > > > > > > > > All newly discovered partitions will be consumed from the > > earliest > > > > > offset > > > > > > possible. > > > > > > > > > > > > Thanks for the reminder! I checked the logic of KafkaSource and > > found > > > > > that > > > > > > new partitions will start from the offset initializer specified > by > > > the > > > > > user > > > > > > instead of the earliest. We need to correct this behavior to > avoid > > > > > dropping > > > > > > messages from new partitions. > > > > > > > > > > > > > Job restarts from checkpoint > > > > > > > > > > > > I think the current logic guarantees the exactly-once semantic. > New > > > > > > partitions created after the checkpoint will be re-discovered > again > > > and > > > > > > picked up by the source. > > > > > > > > > > > > @John: > > > > > > > > > > > > > If you want to be a little conservative with the default, 5 > > minutes > > > > > might > > > > > > be better than 30 seconds. > > > > > > > > > > > > Thanks for the suggestion! I tried to find the equivalent config > in > > > > Kafka > > > > > > but missed it. It would be neat to align with the default value > of > > " > > > > > > metadata.max.age.ms". > > > > > > > > > > > > @Gabor: > > > > > > > > > > > > > removed partition handling is not yet added > > > > > > > > > > > > There was a detailed discussion about removing partitions [1] but > > it > > > > > looks > > > > > > like this is not an easy task considering the potential data loss > > and > > > > > state > > > > > > inconsistency. I'm afraid there's no clear plan on this one and > > maybe > > > > we > > > > > > could trigger a new discussion thread about how to correctly > handle > > > > > removed > > > > > > partitions. > > > > > > > > > > > > [1] > > https://lists.apache.org/thread/7r4h7v5k281w9cnbfw9lb8tp56r30lwt > > > > > > > > > > > > Best regards, > > > > > > Qingsheng > > > > > > > > > > > > > > > > > > On Fri, Jan 13, 2023 at 4:33 PM Gabor Somogyi < > > > > gabor.g.somo...@gmail.com > > > > > > > > > > > > wrote: > > > > > > > > > > > > > +1 on the overall direction, it's an important feature. > > > > > > > > > > > > > > I've had a look on the latest master and looks like removed > > > partition > > > > > > > handling is not yet added but I think this is essential. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > https://github.com/apache/flink/blob/28c3e1a3923ba560b559a216985c1abeb794ebaa/flink-connectors/flink-connector-kafka/src/main/java/org/apache/flink/connector/kafka/source/enumerator/KafkaSourceEnumerator.java#L305 > > > > > > > > > > > > > > If a partition all of a sudden disappears then it could lead to > > > data > > > > > > loss. > > > > > > > Are you planning to add it? > > > > > > > If yes then when? > > > > > > > > > > > > > > G > > > > > > > > > > > > > > > > > > > > > On Fri, Jan 13, 2023 at 9:22 AM John Roesler < > > vvcep...@apache.org> > > > > > > wrote: > > > > > > > > > > > > > > > Thanks for this proposal, Qingsheng! > > > > > > > > > > > > > > > > If you want to be a little conservative with the default, 5 > > > minutes > > > > > > might > > > > > > > > be better than 30 seconds. > > > > > > > > > > > > > > > > The equivalent config in Kafka seems to be > metadata.max.age.ms > > ( > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > https://kafka.apache.org/documentation/#consumerconfigs_metadata.max.age.ms > > > > > > > ), > > > > > > > > which has a default value of 5 minutes. > > > > > > > > > > > > > > > > Other than that, I’m in favor. I agree, this should be on by > > > > default. > > > > > > > > > > > > > > > > Thanks again, > > > > > > > > John > > > > > > > > > > > > > > > > On Fri, Jan 13, 2023, at 08:26, Leonard Xu wrote: > > > > > > > > > Thanks Qingsheng for driving this, enable the dynamic > > partition > > > > > > > > > discovery would be very useful for kafka topic scale > > partitions > > > > > > > > > scenarios. > > > > > > > > > > > > > > > > > > +1 for the change. > > > > > > > > > > > > > > > > > > CC: Becket > > > > > > > > > > > > > > > > > > > > > > > > > > > Best, > > > > > > > > > Leonard > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >> On Jan 13, 2023, at 3:15 PM, Jark Wu <imj...@gmail.com> > > > wrote: > > > > > > > > >> > > > > > > > > >> +1 for the change. I think this is beneficial for users > and > > is > > > > > > > > compatible. > > > > > > > > >> > > > > > > > > >> Best, > > > > > > > > >> Jark > > > > > > > > >> > > > > > > > > >> On Fri, 13 Jan 2023 at 14:22, 何军 <xuehaijux...@gmail.com> > > > > wrote: > > > > > > > > >> > > > > > > > > >>>> > > > > > > > > >>>> +1 for this idea, we have enabled kafka dynamic > partition > > > > > > discovery > > > > > > > in > > > > > > > > >>> all > > > > > > > > >>>> jobs. > > > > > > > > >>>> > > > > > > > > >>>> > > > > > > > > >>> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > Best, > > > > Benchao Li > > > > > > > > > >
