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https://issues.apache.org/jira/browse/ZOOKEEPER-2899?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Yicheng Fang updated ZOOKEEPER-2899:
------------------------------------
    Comment: was deleted

(was: Aggregated log of the 5 node ensemble, minus noisy connection logs)

> Zookeeper not receiving packets after ZXID overflows
> ----------------------------------------------------
>
>                 Key: ZOOKEEPER-2899
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2899
>             Project: ZooKeeper
>          Issue Type: Bug
>          Components: leaderElection
>    Affects Versions: 3.4.5
>         Environment: 5 host ensemble, 1500+ client connections each, 300K+ 
> nodes
> OS: Ubuntu precise
> JAVA 7
> JuniperQFX510048T NIC, 10000Mb/s, ixgbe driver
> 6 core Intel(R)_Xeon(R)_CPU_E5-2620_v3_@_2.40GHz
> 4 HDD 600G each 
>            Reporter: Yicheng Fang
>         Attachments: image12.png, image13.png, zk_20170309_wo_noise.log
>
>
> ZK was used with Kafka (version 0.10.0) for coordination. We had a lot of 
> Kafka consumers writing  consumption offsets to ZK.
> We observed the issue two times within the last year. Each time after ZXID 
> overflowed, ZK was not receiving packets even though leader election looked 
> successful from the logs, and ZK servers were up. As a result, the whole 
> Kafka system came to a halt.
> As an attempt to reproduce (and hopefully fixing) the issue, I set up test ZK 
> and Kafka clusters and feed them with like-production test traffic. Though 
> not really able to reproduce the issue, I did see that the Kafka consumers, 
> which used ZK clients, essentially DOSed the ensemble, filling up the 
> `submittedRequests` in `PrepRequestProcessor`, causing even 100ms+ read 
> latencies.
> More details are included in the comments.



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