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From "T Jake Luciani (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-2034) Make Read Repair unnecessary when Hinted Handoff is enabled
Date Mon, 08 Aug 2011 14:48:27 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-2034?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13080979#comment-13080979
] 

T Jake Luciani commented on CASSANDRA-2034:
-------------------------------------------

Comments on v8:

   - You are still waiting on hints in the client, I don't think we need CreationTimeAwareFuture
anymore.
   - I don't think local hints needs to be put on it's own queue / thread-pool. Just write
the hint to the local mutation queue and increment the hint counters.
   - The shutdown process should not wait for the mutation map to expire, it should simply
write any outstanding hints from the map and shutdown.


Nitpik:
   - The new expiring map logic is backwards in my opinion. I would rather see the expiration
callback handle the hint write, then see the MessageService call storageproxy.





> Make Read Repair unnecessary when Hinted Handoff is enabled
> -----------------------------------------------------------
>
>                 Key: CASSANDRA-2034
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2034
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Jonathan Ellis
>            Assignee: Patricio Echague
>             Fix For: 1.0
>
>         Attachments: 2034-formatting.txt, CASSANDRA-2034-trunk-v2.patch, CASSANDRA-2034-trunk-v3.patch,
CASSANDRA-2034-trunk-v4.patch, CASSANDRA-2034-trunk-v5.patch, CASSANDRA-2034-trunk-v6.patch,
CASSANDRA-2034-trunk-v7.patch, CASSANDRA-2034-trunk-v8.patch, CASSANDRA-2034-trunk.patch
>
>   Original Estimate: 8h
>  Remaining Estimate: 8h
>
> Currently, HH is purely an optimization -- if a machine goes down, enabling HH means
RR/AES will have less work to do, but you can't disable RR entirely in most situations since
HH doesn't kick in until the FailureDetector does.
> Let's add a scheduled task to the mutate path, such that we return to the client normally
after ConsistencyLevel is achieved, but after RpcTimeout we check the responseHandler write
acks and write local hints for any missing targets.
> This would making disabling RR when HH is enabled a much more reasonable option, which
has a huge impact on read throughput.

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