What is replica.fetch.min.bytes set to? On 2/8/14 1:22 PM, "Jay Kreps" <jay.kr...@gmail.com> wrote:
>Hey guys, > >I was running the end-to-end latency test (kafka.TestEndToEndLatency) and >saw something a little weird. This test runs a producer and a consumer and >sends a single message at a time and measures the round-trip time from the >producer's send to the consumer getting the message. > >With replication-factor=1 I see very consistent performance with >end-to-end >latency at 0.4-0.5 ms which is extremely good. > >But with replication factor=2 I see something like this: > >count latency >1000 1.9 ms >2000 1.8 ms >3000 1.4 ms >4000 1.7 ms >5000 102.6 ms >6000 101.4 ms >7000 102.4 ms >8000 1.6 ms >9000 101.5 ms > >This pattern is very reproducible, essentially every 4-5k messages things >slow down to an average round trip of 100ms and then pick back up again. > >Note that this test is not using the new producer. > >Have we seen this before. The issue could be in the producer >acknowledgement or in the highwatermark advancement or fetch request, but >I >notice that the default fetch max wait is 100ms which makes me think there >is a bug in the async request handling that causes it to wait until the >timeout. Any ideas? If not I'll file a bug... > >-Jay
