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From Robert Coli <>
Subject Re: PendingTasks: What does it mean inside Cassandra?
Date Tue, 01 Oct 2013 19:22:25 GMT
On Wed, Aug 28, 2013 at 5:47 AM, Girish Kumar <>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."
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.


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