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Posted to dev@cassandra.apache.org by Robert Coli <rc...@eventbrite.com> on 2013/10/01 21:22:25 UTC
Re: PendingTasks: What does it mean inside Cassandra?
On Wed, Aug 28, 2013 at 5:47 AM, Girish Kumar <gi...@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
Re: PendingTasks: What does it mean inside Cassandra?
Posted by Robert Coli <rc...@eventbrite.com>.
On Thu, Oct 3, 2013 at 8:28 AM, Tyler Hobbs <ty...@datastax.com> wrote:
>
> On Thu, Oct 3, 2013 at 8:37 AM, Girish Kumar <gi...@gmail.com>wrote:
>
>> Additional capacity meaning add more writers and reader threads to handle
>> the requests ?
>
>
> I think he means adding more nodes.
>
The Doc I am quoting almost certainly means adding more nodes.
=Rob
Re: PendingTasks: What does it mean inside Cassandra?
Posted by Tyler Hobbs <ty...@datastax.com>.
On Thu, Oct 3, 2013 at 8:37 AM, Girish Kumar <gi...@gmail.com>wrote:
> Additional capacity meaning add more writers and reader threads to handle
> the requests ?
I think he means adding more nodes.
--
Tyler Hobbs
DataStax <http://datastax.com/>
Re: PendingTasks: What does it mean inside Cassandra?
Posted by Girish Kumar <gi...@gmail.com>.
>>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 <rc...@eventbrite.com> wrote:
> On Wed, Aug 28, 2013 at 5:47 AM, Girish Kumar <gi...@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
>
>
Re: PendingTasks: What does it mean inside Cassandra?
Posted by Girish Kumar <gi...@gmail.com>.
>>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 <rc...@eventbrite.com> wrote:
> On Wed, Aug 28, 2013 at 5:47 AM, Girish Kumar <gi...@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
>
>