Yeah, using acks=0 should result in higher throughput since we are not limited by the roundtrip time to the broker.
Btw. regarding in-flight requests: With acks = 1 (or -1), can we send a message batch to a partition before the brokers "acked" a previous request? Doesn't it risk getting messages out of order? On Mon, Jul 27, 2015 at 9:41 AM, Guozhang Wang <wangg...@gmail.com> wrote: > I think there is still a subtle difference between "async with acks = 0" > and "async with callback", that when the #.max-inflight-requests has > reached the subsequent requests cannot be sent until previous responses are > returned (which could happen, for example, when the broker is slow / > network issue happens) in the second case but not in the first. > > Given this difference, I feel there are still scenarios, though probably > rare, that users would like to use "acks = 0" even with new producer's > callbacks. > > Guozhang > > On Mon, Jul 27, 2015 at 9:25 AM, Mayuresh Gharat <gharatmayures...@gmail.com >> wrote: > >> So basically this means that with acks = 0, their is no guarantee that the >> message has been received by Kafka broker. I am just wondering, why would >> anyone be using acks = 0, since anyone using kafka and doing >> producer.send() would want that, their message got to kafka brokers. Also >> as Jay said, with new producer with async mode, clients will not have to >> wait for the response since it will be handled in callbacks. So the use of >> acks = 0 sounds very rare to me and I am not able to think of an usecase >> around it. >> >> Thanks, >> >> Mayuresh >> >> On Sun, Jul 26, 2015 at 2:40 PM, Gwen Shapira <gshap...@cloudera.com> >> wrote: >> >> > Aha! Yes, I was missing the part with the dummy response. >> > Thank you! >> > >> > Gwen >> > >> > >> > On Sun, Jul 26, 2015 at 2:17 PM, Ewen Cheslack-Postava >> > <e...@confluent.io> wrote: >> > > It's different because it changes whether the client waits for the >> > response >> > > from the broker at all. Take a look at >> > NetworkClient.handleCompletedSends, >> > > which fills in dummy responses when a response is not expected (and >> that >> > > flag gets set via Sender.produceRequest using acks != 0 as a flag to >> > > ClientRequest). This means that the producer will invoke the callback & >> > > resolve the future as soon as the request hits the TCP buffer on the >> > > client. At that point, the behavior of the broker wrt generating a >> > response >> > > doesn't matter -- the client isn't waiting on that response anyway. >> > > >> > > This definitely is faster since you aren't waiting for the round trip, >> > but >> > > it seems like it is of questionable value with the new producer as Jay >> > > explained. It is slightly better than just assuming records have been >> > sent >> > > as soon as you call Producer.send() in this shouldn't trigger a >> callback >> > > until the records have made it through the internal KafkaProducer >> > > buffering. But since it still has to make it through the TCP buffers it >> > > doesn't really guarantee anything that useful. >> > > >> > > -Ewen >> > > >> > > >> > > On Sun, Jul 26, 2015 at 1:40 PM, Gwen Shapira <gshap...@cloudera.com> >> > wrote: >> > > >> > >> What bugs me is that even with acks = 0, the broker will append to >> > >> local log before responding (unless I'm misreading the code), so I >> > >> don't see why a client with acks = 0 will be any faster. Unless the >> > >> client chooses to not wait for response, which is orthogonal to acks >> > >> parameter. >> > >> >> > >> On Mon, Jul 20, 2015 at 8:52 AM, Jay Kreps <j...@confluent.io> wrote: >> > >> > acks=0 is a one-way send, the client doesn't need to wait on the >> > >> response. >> > >> > Whether this is useful sort of depends on the client implementation. >> > The >> > >> > new java producer does all sends async so "waiting" on a response >> > isn't >> > >> > really a thing. For a client that lacks this, though, as some of >> them >> > do, >> > >> > acks=0 will be a lot faster. >> > >> > >> > >> > It also makes some sense in terms of what is completed when the >> > request >> > >> is >> > >> > considered satisfied >> > >> > acks = 0 - message is written to the network (buffer) >> > >> > acks = 1 - message is written to the leader log >> > >> > acks = -1 - message is committed >> > >> > >> > >> > -Jay >> > >> > >> > >> > On Sat, Jul 18, 2015 at 10:50 PM, Gwen Shapira < >> gshap...@cloudera.com >> > > >> > >> > wrote: >> > >> > >> > >> >> Hi, >> > >> >> >> > >> >> I was looking into the different between acks = 0 and acks = 1 in >> the >> > >> >> new producer, and was a bit surprised at what I found. >> > >> >> >> > >> >> Basically, if I understand correctly, the only difference is that >> > with >> > >> >> acks = 0, if the leader fails to append locally, it closes the >> > network >> > >> >> connection silently and with acks = 1, it sends an actual error >> > >> >> message. >> > >> >> >> > >> >> Which seems to mean that with acks = 0, any failed produce will >> lead >> > >> >> to metadata refresh and a retry (because network error), while >> acks = >> > >> >> 1 will lead to either retries or abort, depending on the error. >> > >> >> >> > >> >> Not only this doesn't match the documentation, it doesn't even make >> > >> >> much sense... >> > >> >> "acks = 0" was supposed to somehow makes things "less safe but >> > >> >> faster", and it doesn't seem to be doing that any more. I'm not >> even >> > >> >> sure there's any case where the "acks = 0" behavior is desirable. >> > >> >> >> > >> >> Is it my misunderstanding, or did we somehow screw up the logic >> here? >> > >> >> >> > >> >> Gwen >> > >> >> >> > >> >> > > >> > > >> > > >> > > -- >> > > Thanks, >> > > Ewen >> > >> >> >> >> -- >> -Regards, >> Mayuresh R. Gharat >> (862) 250-7125 >> > > > > -- > -- Guozhang
