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From "Quentin Conner (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6127) vnodes don't scale to hundreds of nodes
Date Tue, 05 Nov 2013 13:55:25 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6127?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13813928#comment-13813928
] 

Quentin Conner commented on CASSANDRA-6127:
-------------------------------------------

Good cpu profile results were obtained last night with the 1.2.9 code line.  Switching over
to the cassandra-1.2 HEAD this morning for up-to-date analysis.
CPU profile of 1.2.9 showed bottleneck was computation of sum for the ArrivalWindow deque
members (inter-arrival times of gossip messages).

> vnodes don't scale to hundreds of nodes
> ---------------------------------------
>
>                 Key: CASSANDRA-6127
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6127
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>         Environment: Any cluster that has vnodes and consists of hundreds of physical
nodes.
>            Reporter: Tupshin Harper
>            Assignee: Jonathan Ellis
>         Attachments: 6000vnodes.patch, AdjustableGossipPeriod.patch, delayEstimatorUntilStatisticallyValid.patch
>
>
> There are a lot of gossip-related issues related to very wide clusters that also have
vnodes enabled. Let's use this ticket as a master in case there are sub-tickets.
> The most obvious symptom I've seen is with 1000 nodes in EC2 with m1.xlarge instances.
Each node configured with 32 vnodes.
> Without vnodes, cluster spins up fine and is ready to handle requests within 30 minutes
or less. 
> With vnodes, nodes are reporting constant up/down flapping messages with no external
load on the cluster. After a couple of hours, they were still flapping, had very high cpu
load, and the cluster never looked like it was going to stabilize or be useful for traffic.



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