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From Ricardo Vilaça <rmvil...@di.uminho.pt>
Subject Re: HBase Tuning
Date Fri, 12 Oct 2012 10:56:52 GMT
Hi,

Em 11/10/12 04:24, Stack escreveu:
> On Wed, Oct 10, 2012 at 5:51 AM, Ricardo Vilaça <rmvilaca@di.uminho.pt> wrote:
>> However, when adding an additional client node, with also 400 clients,
>> the latency increases 3 times,
>> but the RegionServers remains idle more than 80%. I had tried different
>> values for the hbase.regionserver.handler.count and also
>> for the hbase.client.ipc.pool size and type but without any improvement.
>>
> I was going to suggest that it sounded like all handlers are
> occupied... but it sounds like you tried upping them.
Yes, had already tried to increase to 200 but without improvement
on the application latency. However, the output of the active IPC
handlers, using the Web interface,
is strange. For region servers  I can see in a given instant at most 4
IPC handler active but if I
see the state of all other IPC handlers they are waiting for 0 seconds.
In the master the IPC handlers are also almost all in the waiting state
but for a few seconds.
> Is this going from one client node (serving 400 clients) to two client
> nodes (serving 800 clients)?
Yes, the huge increase in latency is when going for one client node to
two client nodes. However, increasing the number of clients in a single
node also adds to latency but a small increase.
> Where are you measuring from?  Application side?  Can you figure if we
> are binding up in HBase or in the client node?
This measures are from the application  side. As the huge increase in
latency
is happening when increasing the number of clients I suspect that the
binding up is in the
HBase maybe due to some incorrect configuration.

> What does a client node look like?  It is something hosting an hbase
> client?  A webserver or something?
Yes, the client node is hosting an HBase client.
>> Is there any configuration parameter that can improve the latency with
>> several concurrent threads and more than one HBase client node
>> and/or which JMX parameters should I monitor on RegionServers to check
>> what may be causing this and how could I achieve better utilization of CPU
>> at RegionServers?
>>
> It sounds like all your data is memory resident given its size and the
> lack of iowait.  Is that so?  Studying the regionserver metrics, are
> they fairly constant across the addition of the new client node?

Yes, all data is memory resident. As far as I can see, the regionserver
metrics are
fairly constant.

Thanks,

-- 
Ricardo Vilaça

---
High-Assurance Software Lab
INESC TEC & Universidade do Minho
http://gsd.di.uminho.pt/members/rmvilaca


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