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From Nate McCall <n...@thelastpickle.com>
Subject Re: Large # of Pending Tasks?
Date Mon, 26 Aug 2013 15:06:44 GMT
Interesting - my understanding is that the only places where stages are
capped at "available processors" have to do with clustering operations (see
the static initializer in o.a.c.concurrent.StageManager).

What version are you using, by the way? Most likely I'm missing something
though.


On Mon, Aug 26, 2013 at 9:36 AM, Girish Kumar <girishkumarbk@gmail.com>wrote:

> This is the 'Active Count' as observed on jconsole under
> 'org.apache.cassandra.request' ReadStage->Attributes.  Below details...
>
>
> ActiveCount -> 12
> ..
> Core Pool Size -> 192
> Core Threads -> 192
> CurrentlyBlockedTasks ->  0
> MaximumThreads -> 192
> PendingTasks -> 691
> TotalBlockedTasks -> 0
>
> I expect active count to go upto 192 as those many threads are available
> to handle requests ? Am I missing reading something here?
>
> I observe that Active Count never goes beyond 24 and Pending Tasks Count
> keeps building up?
>
> So question is what's the relation between Active count and max threads
> available in the pool for execution?
>
> Thanks,
> /BK
>
>
>
>
>
> On Mon, Aug 26, 2013 at 7:28 PM, Nate McCall <nate@thelastpickle.com>wrote:
>
>> I'm not quite sure what you mean by 'active task count' - what is the
>> output of 'nodetool tpstats' when you run this test?
>>
>>
>> On Mon, Aug 26, 2013 at 4:39 AM, Girish Kumar <girishkumarbk@gmail.com>wrote:
>>
>>> Hi,
>>>
>>> I'm using a single node Cassandra on 24 Core/48GB system.  I have set
>>> my writers and readers (in yaml) to be around 192 for both and read and
>>> write.  In this mode, when stressed with 192 threads for inserts and reads,
>>> what I observed via the jconsole of 'client request' the active read and
>>> write tasks never go beyond 24.  However there are as many as 192 pending
>>> tasks.  I was expecting Cassandra server to utilize the threads that
>>> are created using yaml and perform as many parallel inserts and reads.
>>>
>>> Why cassandra active task count doesn't go beyond 24 when the actual
>>> writers and readers are around 192 ?
>>>
>>> Any thoughts?
>>> /BK
>>>
>>
>>
>

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