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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 Thu, 07 Nov 2013 15:19:17 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6127?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13816037#comment-13816037
] 

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

Good morning.  We saw the same CPU usage profile with cassandra-1.2 8e7d7285cdeac4f2527c933280d595bbddd26935
(which included the patch to not flush peers CF).  

CPU time was spent in looking up EndpointState or spent in PHI calculation.  No surprises
were found.  No race conditions, no deadlocks or mutex/monitor contention.

I do not know if flapping happens in 1.2 head without vnodes.  I will find out today, if I
can get the nodes (having trouble this morning allocating from EC2).  Will keep trying (Fridays
seem better) but could slip into the weekend...


> 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: 2013-11-05_18-04-03_no_compression_cpu_time.png, 2013-11-05_18-09-38_compression_on_cpu_time.png,
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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