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From Jeff Kubina <jeff.kub...@gmail.com>
Subject Re: questions regarding accumulo tracing
Date Thu, 13 Aug 2015 19:16:21 GMT
On Thu, Aug 13, 2015 at 2:52 PM, Josh Elser <josh.elser@gmail.com> wrote:

> 1. Regarding the information above about accumulo tracing, if more than
>> one server is listed in $ACCUMULO_HOME/conf/tracers how do the clients
>> select the trace server to send their trace data to?
>>
>
> Tracers register themselves in ZooKeepers and the client tracing libraries
> know to look in ZooKeeper to find them. You as a user shouldn't have to
> worry about it -- it should happen automagically for you.


I wanted to know how well balanced the tracing data is processed.

Is there a recommended system design with respect to the tracing servers?
Should we dedicate a few nodes to being just tracing servers or is it best
to have each tablet server also be a tracing server? If we make each tablet
server also a tracing server will each tablet server just send its tracing
data to the local tracing server?


> 2. As an admin what is the best way to determine which tables have
>> recently been traced?
>>
>
> I'm not entirely sure what you mean by "[tables that have been recently
> traced]". You can look at the "Recent Traces" page on the monitor to get a
> list of the traces in the last X minutes.
>
> Many operations going on in Accumulo will be getting traced. If you have
> an active system, you'll constantly see new traces for minor compactions
> and major compactions.


Sometimes a trace will cause very high system CPU utilization (90%) and
system load on the tracing server. When this becomes detrimental to the
server I would like to determine what table was being traced at that time
(to get the user/developer to refine the trace).

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