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https://issues.apache.org/jira/browse/KAFKA-1251?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13942454#comment-13942454
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Jay Kreps commented on KAFKA-1251:
----------------------------------

Guozhong,

1. No idea. I did a comparison between a Coda Hale Histogram and my metrics 
(both stand-alone and in the new producer) to make sure I hadn't blown 
something. I haven't done any experiments with the old producer.

2. I agree the selector metrics are a little unintuitive. How about this:
"select-calls-per-second" => "Number of times the I/O layer checked for new I/O 
to perform per second",
"io-wait-time-avg-ns" => "The average length of time the I/O thread speant 
waiting for a socket ready for reads or writes in ns" 
"io-wait-percentage" => "The fraction of time the I/O thread spent waiting."
"io-time-avg-ns" => "The average length of time for I/O per select call in 
nanoseconds."
"io-percentage" => "The fraction of time the I/O thread spent doing I/O"
"batch-size-avg" => "The average number of bytes sent per partition 
per-request." (calling it per batch doesn't help because what is a batch)

select-calls-per-second is a bit of an implementation detail, but it is 
important to understand how many iterations the selector is actually doing to 
interpret some of the other metrics.

I actually think waiting-threads and ready-partitions work fine without the 
-count suffix. As in the phase "there are 5 waiting threads" or "there are 12 
ready partitions".

> Add metrics to the producer
> ---------------------------
>
>                 Key: KAFKA-1251
>                 URL: https://issues.apache.org/jira/browse/KAFKA-1251
>             Project: Kafka
>          Issue Type: Sub-task
>          Components: producer 
>            Reporter: Jay Kreps
>            Assignee: Jay Kreps
>         Attachments: KAFKA-1251.patch, KAFKA-1251_2014-03-19_10:19:27.patch, 
> KAFKA-1251_2014-03-19_10:29:05.patch, KAFKA-1251_2014-03-19_17:30:32.patch
>
>
> Currently there are no metrics.



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