So, the "good news" is that the problem came back again. The bad news is that I disabled debug logs as it was filling disk (and I had other fires to put out). I will re-enable debug logs and wait for it to happen again.
On Thu, Feb 6, 2014 at 4:05 AM, Neha Narkhede <neha.narkh...@gmail.com> wrote: > Carl, > > It will help if you can list the steps to reproduce this issue starting > from a fresh installation. Your setup, the way it stands, seems to have > gone through some config and state changes. > > Thanks, > Neha > > > On Wed, Feb 5, 2014 at 5:17 PM, Joel Koshy <jjkosh...@gmail.com> wrote: > >> On Wed, Feb 05, 2014 at 04:51:16PM -0800, Carl Lerche wrote: >> > So, I tried enabling debug logging, I also made some tweaks to the >> > config (which I probably shouldn't have) and craziness happened. >> > >> > First, some more context. Besides the very high network traffic, we >> > were seeing some other issues that we were not focusing on yet. >> > >> > * Even though the log retention was set to 50GB & 24 hours, data logs >> > were getting cleaned up far quicker quicker. I'm not entirely sure how >> > much quicker, but there was definitely far less than 12 hours and 1GB >> > of data. >> > >> > * Kafka was not properly balanced. We had 3 servers, and only 2 of >> > them were partition leaders. One server was a replica for all >> > partitions. We tried to run a rebalance command, but it did not work. >> > We were going to investigate later. >> >> Were any of the brokers down for an extended period? If the preferred >> replica election command failed it could be because the preferred >> replica was catching up (which could explain the higher than expected >> network traffic). Do you monitor the under-replicated partitions count >> on your cluster? If you have that data it could help confirm this. >> >> Joel >> >> > >> > So, after restarting all the kafkas, something happened with the >> > offsets. The offsets that our consumers had no longer existed. It >> > looks like somehow all the contents was lost? The logs show many >> > exceptions like: >> > >> > `Request for offset 770354 but we only have log segments in the range >> > 759234 to 759838.` >> > >> > So, I reset all the consumer offsets to the head of the queue as I did >> > not know of anything better to do. Once the dust settled, all the >> > issues we were seeing vanished. Communication between Kafka nodes >> > appear to be normal, Kafka was able to rebalance, and hopefully log >> > retention will be normal. >> > >> > I am unsure what happened or how to get more debug information. >> > >> > On Wed, Feb 5, 2014 at 12:31 PM, Jay Kreps <jay.kr...@gmail.com> wrote: >> > > Can you enable DEBUG logging in log4j and see what requests are coming >> in? >> > > >> > > -Jay >> > > >> > > >> > > On Tue, Feb 4, 2014 at 9:51 PM, Carl Lerche <m...@carllerche.com> wrote: >> > > >> > >> Hi Jay, >> > >> >> > >> I do not believe that I have changed the replica.fetch.wait.max.ms >> > >> setting. Here I have included the kafka config as well as a snapshot >> > >> of jnettop from one of the servers. >> > >> >> > >> https://gist.github.com/carllerche/4f2cf0f0f6d1e891f482 >> > >> >> > >> The bottom row (89.9K/s) is the producer (it lives on a Kafka server). >> > >> The top two rows are Kafkas on other servers, you can see the combined >> > >> throughput is ~80MB/s >> > >> >> > >> On Tue, Feb 4, 2014 at 9:36 PM, Jay Kreps <jay.kr...@gmail.com> >> wrote: >> > >> > No this is not normal. >> > >> > >> > >> > Checking twice a second (using 500ms default) for new data shouldn't >> > >> cause >> > >> > high network traffic (that should be like < 1KB of overhead). I >> don't >> > >> think >> > >> > that explains things. Is it possible that setting has been >> overridden? >> > >> > >> > >> > -Jay >> > >> > >> > >> > >> > >> > On Tue, Feb 4, 2014 at 9:25 PM, Guozhang Wang <wangg...@gmail.com> >> > >> wrote: >> > >> > >> > >> >> Hi Carl, >> > >> >> >> > >> >> For each partition the follower will also fetch data from the >> leader >> > >> >> replica, even if there is no new data in the leader replicas. >> > >> >> >> > >> >> One thing you can try to increase replica.fetch.wait.max.ms(default >> > >> value >> > >> >> 500ms) so that the followers's fetching request frequency to the >> leader >> > >> can >> > >> >> be reduced, and see if that has some effect on the traffic. >> > >> >> >> > >> >> Guozhang >> > >> >> >> > >> >> >> > >> >> On Tue, Feb 4, 2014 at 8:46 PM, Carl Lerche <m...@carllerche.com> >> wrote: >> > >> >> >> > >> >> > Hello, >> > >> >> > >> > >> >> > I'm running a 0.8.0 Kafka cluster of 3 servers. The service that >> it is >> > >> >> > for is not in full production yet, so the data written to >> cluster is >> > >> >> > minimal (seems to average between 100kb/s -> 300kb/s per >> server). I >> > >> >> > have configured Kafka to have a 3 replicas. I am noticing that >> each >> > >> >> > Kafka server is talking to all the others at a data rate of >> 40MB/s for >> > >> >> > each server (so, a total of 80MB/s for each server). This >> > >> >> > communication is constant. >> > >> >> > >> > >> >> > Is this normal? This seems like very strange behavior and I'm not >> > >> >> > exactly sure how to debug. >> > >> >> > >> > >> >> > Thanks, >> > >> >> > Carl >> > >> >> > >> > >> >> >> > >> >> >> > >> >> >> > >> >> -- >> > >> >> -- Guozhang >> > >> >> >> > >> >> >>
