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From Philippe <watche...@gmail.com>
Subject Re: Meaning of values in tpstats
Date Sun, 11 Dec 2011 14:37:32 GMT
Answer below


> > Pool Name                    Active   Pending      Completed   Blocked
>  All
> > time blocked
> > ReadStage                        27      2166     3565927301         0
> 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 ?
Can anyone confirm for multigetslice ? I want to know if batching is
counterproductive really.

Typically having pending persistently above 0 for ReadStage or
> MutationStage, especially if more than a hand-ful, means that you are
> having a performance issue - either capacity problem or something
> else, as incoming requests will have to wait to be services. Typically
> the most common effect is that you are bottlenecking on I/O and
> ReadStage pending shoots through the roof.

In general, batching is good - but don't overdo it, especially for
> reads, and especially if you're going to disk for the workload.
>
 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.

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