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https://issues.apache.org/jira/browse/KAFKA-706?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sriram Subramanian reassigned KAFKA-706:
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Assignee: Sriram Subramanian
> broker appears to be encoding ProduceResponse, but never sending it
> -------------------------------------------------------------------
>
> Key: KAFKA-706
> URL: https://issues.apache.org/jira/browse/KAFKA-706
> Project: Kafka
> Issue Type: Bug
> Components: core
> Affects Versions: 0.8
> Environment: reproduced on both Mac OS and RH linux, via private
> node.js client
> Reporter: ben fleis
> Assignee: Sriram Subramanian
>
> By all appearances, I seem to be able to convince a broker to periodically
> encode, but never transmit, a ProduceResponse. Unfortunately my client is
> proprietary, but I will share it with Neha via LI channels. But I will
> describe what's going on in the hopes that there's another trivial way to
> reproduce it. (I did search through JIRA, and haven't found anything that
> looks like this.)
> I am running a single instance zookeeper and single broker. I have a client
> that generates configurable amounts of data, tracking what is produced (both
> sent and ACK'd), and what is consumed. I was noticing that when using high
> transfer rates via high frequency single messages, my unack'd queue appeared
> to be getting continuously larger. So, I outfitted my client to log more
> information about correlation ids at various stages, and modified the kafka
> ProducerRequest/ProducerResponse to log (de)serialization of the same. I
> then used tcpdump to intercept all communications between my client and the
> broker. Finally, I configured my client to generate 1 message per ~10ms,
> each payload being approximately 33 bytes; requestAckTimeout was set to
> 2000ms, and requestAcksRequired was set to 1. I used 10ms as I found that
> 5ms or less caused my unacked queue to build up due to system speed -- it
> simply couldn't keep up. 10ms keeps the load high, but just manageable.
> YMMV with that param. All of this is done on a single host, over loopback.
> I ran it on both my airbook, and a well setup RH linux box, and found the
> same problem.
> At startup, my system logged "expired" requests - meaning reqs that were
> sent, but for which no ACK, positive or negative, was seen from the broker,
> within 1.25x the requestAckTimeout (ie, 2500ms). I would let it settle until
> the unacked queue was stable at or around 0.
> What I found is this: ACKs are normally generated within milliseconds. This
> was demonstrated by my logging added to the scala ProducerRe* classes, and
> they are normally seen quickly by my client. But when the actual error
> occurs, namely that a request is ignored, the ProducerResponse class *does*
> encode the correct correlationId; however, a response containing that ID is
> never sent over the network, as evidenced by my tcpdump traces. In my
> experience this would take anywhere from 3-15 seconds to occur after the
> system was warm, meaning that it's 1 out of several hundred on average that
> shows the condition.
> While I can't attach my client code, I could attach logs; but since my
> intention is to share the code with LI people, I will wait to see if that's
> useful here.
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