[jira] [Commented] (KAFKA-10177) Replace/improve Percentiles metrics

2020-06-26 Thread Sophie Blee-Goldman (Jira)


[ 
https://issues.apache.org/jira/browse/KAFKA-10177?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=17146681#comment-17146681
 ] 

Sophie Blee-Goldman commented on KAFKA-10177:
-

I haven't personally looked into HrdHistogram specifically, but I think the 
approach of porting over an existing and well-tested implementation is the 
right way to go.

It's probably not worth an extra dependency and shouldn't be too complicated to 
re-implement a reasonable percentiles algorithm (famous last words, I know...)

> Replace/improve Percentiles metrics
> ---
>
> Key: KAFKA-10177
> URL: https://issues.apache.org/jira/browse/KAFKA-10177
> Project: Kafka
>  Issue Type: Improvement
>  Components: metrics
>Reporter: Sophie Blee-Goldman
>Priority: Major
>
> There's an existing – but seemingly unused – implementation of percentile 
> metrics that we attempted to use for end-to-end latency metrics in Streams. 
> Unfortunately a number of limitations became apparent, and we ultimately 
> pulled the metrics from the 2.6 release pending further 
> investigation/improvement.
> The problems we encountered were
>  # Need to set a static upper/lower limit for the values
>  # Not well suited to a distribution with a long tail, ie setting the max 
> value too high caused the accuracy to plummet
>  # Required a lot of memory per metric for reasonable accuracy and caused us 
> to hit OOM (unclear if there was actually a memory leak, or it was just 
> gobbling up unnecessarily large amounts in general)
> Since the Percentiles class is part of the public API, we may need to create 
> a new class altogether and possibly deprecate/remove the old one. 
> Alternatively we can consider just re-implementing the existing class from 
> scratch, and just deprecating the current constructors and associated 
> implementation (eg the constructor accepts a max)



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[jira] [Commented] (KAFKA-10177) Replace/improve Percentiles metrics

2020-06-24 Thread Tom Bentley (Jira)


[ 
https://issues.apache.org/jira/browse/KAFKA-10177?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=17143599#comment-17143599
 ] 

Tom Bentley commented on KAFKA-10177:
-

Have you considered using HrdHistogram, or reimplementing some of the ideas 
from it if you don't want to add it as a dependency?

> Replace/improve Percentiles metrics
> ---
>
> Key: KAFKA-10177
> URL: https://issues.apache.org/jira/browse/KAFKA-10177
> Project: Kafka
>  Issue Type: Improvement
>  Components: metrics
>Reporter: Sophie Blee-Goldman
>Priority: Major
>
> There's an existing – but seemingly unused – implementation of percentile 
> metrics that we attempted to use for end-to-end latency metrics in Streams. 
> Unfortunately a number of limitations became apparent, and we ultimately 
> pulled the metrics from the 2.6 release pending further 
> investigation/improvement.
> The problems we encountered were
>  # Need to set a static upper/lower limit for the values
>  # Not well suited to a distribution with a long tail, ie setting the max 
> value too high caused the accuracy to plummet
>  # Required a lot of memory per metric for reasonable accuracy and caused us 
> to hit OOM (unclear if there was actually a memory leak, or it was just 
> gobbling up unnecessarily large amounts in general)
> Since the Percentiles class is part of the public API, we may need to create 
> a new class altogether and possibly deprecate/remove the old one. 
> Alternatively we can consider just re-implementing the existing class from 
> scratch, and just deprecating the current constructors and associated 
> implementation (eg the constructor accepts a max)



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