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From aaron morton <aa...@thelastpickle.com>
Subject Re: active/pending queue lengths
Date Tue, 14 Feb 2012 09:01:19 GMT
And the output from tpstats is ?

A
-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com

On 14/02/2012, at 12:43 PM, Franc Carter wrote:

> 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
>> 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
> 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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