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From "Jonathan Ellis (JIRA)" <>
Subject [jira] Updated: (CASSANDRA-2058) Nodes periodically spike in load
Date Wed, 26 Jan 2011 21:50:44 GMT


Jonathan Ellis updated CASSANDRA-2058:

    Attachment: 2058.txt

Brandon's testing has narrowed the culprit down to CASSANDRA-1959.  As discussed on CASSANDRA-2054,
the main problem there is with the NonBlockingHashMap introduced to track timed out latencies.

This patch reverts that and takes a different approach, of tracking the latency in the callback
map.  This means that we need a unique messageId for each target we send a message to.  The
Right Way to do this would be to have Message objects only contain the data to send, not the
From address and not the messageId.  Refactoring Message is outside our scope here though,
so instead we create a new Message for each target.

This does let us clean up the callback map in ResponseVerbHandler instead of in each Callback.
 (That is what is going on in the changes to QRH, WRH, and AR.)

> Nodes periodically spike in load
> --------------------------------
>                 Key: CASSANDRA-2058
>                 URL:
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 0.6.10
>            Reporter: David King
>         Attachments: 2058.txt, cassandra.pmc01.log.bz2, cassandra.pmc14.log.bz2, graph
a.png, graph b.png
> (Filing as a placeholder bug as I gather information.)
> At ~10p 24 Jan, I upgraded our 20-node cluster from 0.6.8->0.6.10, turned on the DES,
and moved some CFs from one KS into another (drain whole cluster, take it down, move files,
change schema, put it back up). Since then, I've had four storms whereby a node's load will
shoot to 700+ (400% CPU on a 4-cpu machine) and become totally unresponsive. After a moment
or two like that, its neighbour dies too, and the failure cascades around the ring. Unfortunately
because of the high load I'm not able to get into the machine to pull a thread dump to see
wtf it's doing as it happens.
> I've also had an issue where a single node spikes up to high load, but recovers. This
may or may not be the same issue from which the nodes don't recover as above, but both are
new behaviour

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