One last thing, I have collected a snippet of the network traffic between Kafka instances using tcpdump. However, it contains some customer data and less than a minutes worth was over 1 GB, so I can't really post it here, but I could possibly share offline if it can help debug the issue.
On Thu, Feb 6, 2014 at 11:44 PM, Carl Lerche <m...@carllerche.com> wrote: > Re: > >> Could you also check if the on-disk data size/rate match the network >> traffic? > > While I have not explicitly checked this, I would say that the answer > is no. The network is over 1Gbps and I have setup monitoring for disk > space and nothing out of the norm is happening there. The expected > data is on the order of 500 kbits per sec. > > cheers. > > On Thu, Feb 6, 2014 at 9:06 PM, Jun Rao <jun...@gmail.com> wrote: >> Could you also check if the on-disk data size/rate match the network >> traffic? >> >> Thanks, >> >> Jun >> >> >> On Thu, Feb 6, 2014 at 7:48 PM, Carl Lerche <m...@carllerche.com> wrote: >> >>> 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 >>> >> > >> >> >>> >> > >> >>> >> >>> >> >>>
