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Date: Wed, 7 Jul 2010 12:36:51 -0400 (EDT)
From: "Jonathan Ellis (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
Subject: [jira] Commented: (CASSANDRA-1035) Implement User/Keyspace
 throughput Scheduler
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    [ https://issues.apache.org/jira/browse/CASSANDRA-1035?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12885982#action_12885982 ] 

Jonathan Ellis commented on CASSANDRA-1035:
-------------------------------------------

Right, it looks like what you want is just a SynchronousQueue per keyspace.  Manual wait/notify is more code and error-prone (see the javadoc for wait() -- "A thread can also wake up without being notified, interrupted, or timing out, a so-called spurious wakeup...")

Go ahead and just initialize the scheduler in DD, we already do this with e.g. the partitioner.

> Implement User/Keyspace throughput Scheduler
> --------------------------------------------
>
>                 Key: CASSANDRA-1035
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1035
>             Project: Cassandra
>          Issue Type: Improvement
>    Affects Versions: 0.7
>            Reporter: Stu Hood
>            Assignee: Nirmal Ranganathan
>             Fix For: 0.7
>
>         Attachments: 0001-Adding-the-RequestScheduler-abstraction-and-a-simple.patch, 0002-Thrift-related-changes-for-RequestScheduler-added-a-.patch, 0003-Avro-related-changes-for-RequestScheduler.patch, 0004-Test-case-for-RoundRobinScheduler.patch, 0005-Add-options-for-throttling.patch, 1035-v2.txt, Cassandra-1035.patch
>
>
> To support multiple applications on top of a single Cassandra cluster (and to protect against badly behaving clients) having a very simple scheduler for client operations would be very beneficial.
> Since all tasks are short lived, a sufficient scheduler would probably only need to manage the queue of incoming requests, and weight them based on an assigned ID. The ID could be dynamically determined by using ip, userid or keyspace for instance, and then each Runnable would be assigned an ID.

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