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From "Robert Stupp (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (CASSANDRA-8032) User based request scheduler
Date Tue, 30 Sep 2014 21:54:34 GMT

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Robert Stupp edited comment on CASSANDRA-8032 at 9/30/14 9:54 PM:
------------------------------------------------------------------

{code:title=RoundRobinScheduler}
 * A very basic Round Robin implementation of the RequestScheduler. It handles
 * request groups identified on user/keyspace by placing them in separate
 * queues and servicing a request from each queue in a RoundRobin fashion.
 * It optionally adds weights for each round.
{code}

That (only) scheduler already seems to handle users. But it only has very basic support. Introduction
of a scheduling based on users with priorities (I think that's what you're proposing) is not
a bad option IMO.


was (Author: snazy):
{code:title=RoundRobinScheduler}
 * A very basic Round Robin implementation of the RequestScheduler. It handles
 * request groups identified on user/keyspace by placing them in separate
 * queues and servicing a request from each queue in a RoundRobin fashion.
 * It optionally adds weights for each round.
{code}

> User based request scheduler
> ----------------------------
>
>                 Key: CASSANDRA-8032
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8032
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Mck SembWever
>            Priority: Minor
>
> Today only a keyspace based request scheduler exists.
> Post CASSANDRA-4898 it could be possible to implement a request_scheduler based on users
(from system_auth.credentials) rather than keyspaces. This could offer a finer granularity
of control, from read-only vs read-write users on keyspaces, to application dedicated vs ad-hoc
users. Alternatively it could also offer a granularity larger and easier to work with than
per keyspace.
> The request scheduler is a useful concept but i think that setups with enough nodes often
favour separate clusters rather than either creating separate virtual datacenters or using
the request scheduler. To give the request scheduler another, and more flexible, implementation
could especially help those users that don't yet have enough nodes to warrant separate clusters,
or even separate virtual datacenters. On such smaller clusters cassandra can still be seen
as an unstable technology because poor consumers/schemas can easily affect, even bring down,
a whole cluster.
> I haven't look into the feasibility of this within the code, but it comes to mind as
rather simple, and i would be interested in offering a patch if the idea carries validity.



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