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From Girish Kumar <girishkuma...@gmail.com>
Subject Re: PendingTasks: What does it mean inside Cassandra?
Date Thu, 03 Oct 2013 13:37:19 GMT
>>Watching trends on these pools for increases in the pending tasks
>>column is an excellent indicator of the need to add additional capacity.

Additional capacity meaning add more writers and reader threads to handle
the requests  ?


On Tue, Oct 1, 2013 at 12:22 PM, Robert Coli <rcoli@eventbrite.com> wrote:

> On Wed, Aug 28, 2013 at 5:47 AM, Girish Kumar <girishkumarbk@gmail.com>wrote:
>
>> When high number of Pending tasks are showing up what it means to
>> cassandra? What are the reasons for high number pending tasks?  Does that
>> mean Cassandra is overloaded ?
>>
>
> It means that tasks have been queued to run inside of a Thread Pool, but
> are not currently running. A given task moves from Pending to Active state,
> and then Completed. "Blocked" is "I attempted to move something from
> Pending to Active, but was unable to."
>
> http://www.datastax.com/docs/1.0/operations/monitoring
> "
> Cassandra maintains distinct thread pools for different stages of
> execution. Each of these thread pools provide statistics on the number of
> tasks that are active, pending and completed. Watching trends on these
> pools for increases in the pending tasks column is an excellent indicator
> of the need to add additional capacity.
> "
>
> =Rob
>
>

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