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
