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From Brandon Wilson <brandon.wilson....@gmail.com>
Subject Re: Thrift API
Date Mon, 06 May 2013 17:44:34 GMT
Thanks for the help. With your help I've dug in and figured out how to
interact with Accumulo using the Thrift API from the client side.

I have one more followup relating to all this metrics and thrift subject
matter and it involves the server side of maintaining the maetrics. It is
my understanding that the Master is maintaining a set of stats about the
system and we get our hands on them using a Thrift call that sends back an
instance of MasterMonitorInfo (I assume this would be the logic behind each
point on the Monitor web page - with a few lines of aggregation code to get
the big picture). From there we have our hands on the per tablet or per
table metrics. What I need to understand is how and how often these are
computed or reset. For example:

1) IndexCacheHits - Is this monotonic? i.e., never reset, simply
accumulating from process startup. Is there essentially a callback to
update the stats on every cache lookup? Is this reset after each time
window?

2) IngestRate - Eric said that this is a decaying average like JMX. Does
this mean that time is broken into discrete blocks and the bytes (or
entries) ingested over that window are computed and added to the decaying
average via some sort of callback?

I hope these make sense. A quick pointer to the classes that maintain the
server-side of these metrics would be great.

Thanks for all the help so far.

-Brandon


On Tue, Apr 30, 2013 at 2:37 PM, Eric Newton <eric.newton@gmail.com> wrote:

>
>
> I have another quick questions about the following measurements for anyone
>> that may know:
>>
>> 1) *QueryRate* - What units is this? Queries (or Entries returned) per
>> sec? Same question as 2) applies here.
>>
>
> Entries/second.
>
>
>> 2) *(Query/Ingest)ByteRate* - Is this over a time window? Is it some
>> sort of exponential decay like the JMX averages.
>>
>
> Yes, exactly like the JMX data.
>
>
>> Also, I assume that, like to the Monitor page, QueryByteRate and
>> QueryRate is actually the ResultSet size and rate?
>>
>
> Yep, it's all the same data.
>
> -Eric
>
>

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