Hi Daniel, I don't have any changes in mind that might be affecting the latency increase from a broker upgrade. Since you're using replication factor 1, it shouldn't be related to the replication protocol or inter-broker network latency.
Are you able to take a profile [1] of the leader broker and make some flame graphs to compare 3.9.1 and 4.0.0? I hope that a 20x difference would be visible on the Wall profile. Thanks, Greg [1] https://github.com/async-profiler/async-profiler On Thu, Aug 21, 2025 at 8:53 AM Daniel Germon <daniel.ger...@lmax.com.invalid> wrote: > Hi Greg, > > I have changed the linger.ms configuration on the producer and yes it > explains the difference in client version latencies, but I am still seeing > the broker latency differences with this configuration. > > Kafka broker 3.9.1, client 4.0.0, linger.ms = 0 > > 50th percentile: 310us > 90th percentile: 414us > 99th percentile: 825us > 99.9th percentile: 9813us > > Kafka broker 4.0.0, client 4.0.0, linger.ms = 0 > > 50th percentile: 8193us > 90th percentile: 10373us > 99th percentile: 11109us > 99.9th percentile: 13812us > > > Regards, > Dan > > This message and its attachments are confidential, may not be disclosed or > used by any person other than the addressee and are intended only for the > named recipient(s). If you are not the intended recipient, please notify > the sender immediately and delete any copies of this message. > > LMAX Group is the holding company of LMAX Exchange, LMAX Global and LMAX > Digital. Our registered address is Yellow Building, 1A Nicholas Road, > London W11 4AN. >
