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From Peter Schuller <peter.schul...@infidyne.com>
Subject Re: Meaning of values in tpstats
Date Mon, 12 Dec 2011 05:27:18 GMT
>> With the slicing, I'm not sure off the top of my head. I'm sure
>> someone else can chime in. For e.g. a multi-get, they end up as
>> independent tasks.
>
> So if I multiget 10 keys, they are fetched in //, consolidated by the
> coodinator and then sent back ?

Took me a while to figure out that // == "parallel" :)

I'm pretty sure (but not entirely, I'd have to check the code) that
the request is forwarded as one request to the necessary node(s); what
I was saying rather was that the individual gets get queued up as
individual tasks to be executed internally in the different stages.
That does lead to parallelism locally on the node (subject to the
concurrent reader setting.


>  Agreed, I followed someone suggestion some time ago to reduce my batch
> sizes and it has helped tremendoulsy. I'm now doing multigetslices in
> batchers of 512 instead of 5000 and I find I no longer have Pendings up so
> high. The most I see now is a couple hundred.

In general, the best balance will depend on the situation. For example
the benefit of batching increases as the latency to the cluster (and
within it) increases, and the negative effects increase as you have
higher demands of low latency on other traffic to the cluster.


-- 
/ Peter Schuller (@scode, http://worldmodscode.wordpress.com)

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