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https://issues.apache.org/jira/browse/ZOOKEEPER-2899?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16193369#comment-16193369
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Yicheng Fang commented on ZOOKEEPER-2899:
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[~maoling] NaH, I have since shifted focus to other tasks because it didn't
seem like I was getting close to reproducing what we saw in prod.
It would be great if you have some ideas that we can try out. We're all ears.
> 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: GC_metric.png, image12.png, image13.png,
> message_in_per_sec.png, metric_volume.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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