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From Franc Carter <franc.car...@sirca.org.au>
Subject Re: active/pending queue lengths
Date Mon, 13 Feb 2012 23:43:35 GMT
On Tue, Feb 14, 2012 at 6:06 AM, aaron morton <aaron@thelastpickle.com>wrote:

> What CL are you reading at ?
>

Quorum


>
> Write ops go to RF number of nodes, read ops go to RF number of nodes 10%
> (the default probability that Read Repair will be running) of the time and
> CL number of nodes 90% of the time. With 2 nodes and RF 2 the QUOURM is 2,
> every request will involve all nodes.
>

Yep, the thing tat confuses is the different behaviour for reading from one
node versus two


>
> As to why the pending list gets longer, do you have some more info ? What
> process are you using to measure ? It's hard to guess why. In this setup
> every node will have the data and should be able to do a local read and
> then on the other node.
>

I have four pycassa clients, two making requests to one server and two
making requests to the other (or all four making requests to the same
server). The requested keys don't overlap and I would expect/assume the
keys are in the keycache

I am looking at the output of nodetool -h tpstats

cheers


> Cheers
>
>
>   -----------------
> Aaron Morton
> Freelance Developer
> @aaronmorton
> http://www.thelastpickle.com
>
> On 14/02/2012, at 12:47 AM, Franc Carter wrote:
>
>
> Hi,
>
> I've been looking at tpstats as various test queries run and I noticed
> something I don't understand.
>
> I have a two node cluster with RF=2 on which I run 4 parallel queries,
> each job goes through a list of keys doing a multiget for 2 keys at a time.
> If two of the queries go to one node and the other two go to a different
> node then the pending queue on the node gets much longer than if they all
> go to the one node.
>
> I'm clearly missing something here as I would have expected the opposite
>
> cheers
>
> --
> *Franc Carter* | Systems architect | Sirca Ltd
>  <marc.zianideferranti@sirca.org.au>
> franc.carter@sirca.org.au | www.sirca.org.au
> Tel: +61 2 9236 9118
>  Level 9, 80 Clarence St, Sydney NSW 2000
> PO Box H58, Australia Square, Sydney NSW 1215
>
>
>


-- 

*Franc Carter* | Systems architect | Sirca Ltd
 <marc.zianideferranti@sirca.org.au>

franc.carter@sirca.org.au | www.sirca.org.au

Tel: +61 2 9236 9118

Level 9, 80 Clarence St, Sydney NSW 2000

PO Box H58, Australia Square, Sydney NSW 1215

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