Max Value from Histogram

[adamdougal]

Hey, 

I'm currently using a histogram to record application response times. I'd like to keep track of the maximum value but can't see that as an option. Is there anything else I can use or can this be added?

I've used DropWizard metrics in the past which supports this http://metrics.dropwizard.io/3.2.3/getting-started.html#histograms

Cheers

[Brian Brazil]

This isn't supported. The fundamental problem is the maximum over what time period? In Prometheus you are meant to be able to calculate over any time period, and thus there's no way to make this work sanely.

--

Brian Brazil

www.robustperception.io

[barmy...@gmail.com]

Couldn't it essentially work the same way as a Gauge but with an if check first to check if the value is greater?

[Brian Brazil]

On 14 August 2017 at 16:08, <barmy...@gmail.com> wrote:

Couldn't it essentially work the same way as a Gauge but with an if check first to check if the value is greater?

That doesn't tell you when the max was, it could be from now or from a month ago. Logs would be a better way to track this. 

Brian

 

On Monday, 14 August 2017 15:19:15 UTC+1, Brian Brazil wrote:

On 14 August 2017 at 14:47, adamdougal <barmy...@gmail.com> wrote:

Hey, 

I'm currently using a histogram to record application response times. I'd like to keep track of the maximum value but can't see that as an option. Is there anything else I can use or can this be added?

I've used DropWizard metrics in the past which supports this http://metrics.dropwizard.io/3.2.3/getting-started.html#histograms

This isn't supported. The fundamental problem is the maximum over what time period? In Prometheus you are meant to be able to calculate over any time period, and thus there's no way to make this work sanely.

--

Brian Brazil

www.robustperception.io

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Brian Brazil

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[barmy...@gmail.com]

Sorry I'm not sure I follow. With my current gauges I can see when they were increased/decreased so I don't understand why I wouldn't be able to here?

Cheers

Adam

On Monday, 14 August 2017 16:23:26 UTC+1, Brian Brazil wrote:

On 14 August 2017 at 16:08, <barmy...@gmail.com> wrote:

Couldn't it essentially work the same way as a Gauge but with an if check first to check if the value is greater?

That doesn't tell you when the max was, it could be from now or from a month ago. Logs would be a better way to track this. 

Brian

 

On Monday, 14 August 2017 15:19:15 UTC+1, Brian Brazil wrote:

On 14 August 2017 at 14:47, adamdougal <barmy...@gmail.com> wrote:

Hey, 

I'm currently using a histogram to record application response times. I'd like to keep track of the maximum value but can't see that as an option. Is there anything else I can use or can this be added?

I've used DropWizard metrics in the past which supports this http://metrics.dropwizard.io/3.2.3/getting-started.html#histograms

This isn't supported. The fundamental problem is the maximum over what time period? In Prometheus you are meant to be able to calculate over any time period, and thus there's no way to make this work sanely.

--

Brian Brazil

www.robustperception.io

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Brian Brazil

www.robustperception.io

[Brian Brazil]

On 15 August 2017 at 10:38, <barmy...@gmail.com> wrote:

Sorry I'm not sure I follow. With my current gauges I can see when they were increased/decreased so I don't understand why I wouldn't be able to here?

You can see snapshots of the gauge, you can't see exactly when they increased/decreased. So for example if the max is 10, and then over the next 5 minutes the max is 4 - we have no way to tell that the max over the last 5 minutes that the max is 4 as all we ever see is that initial 10.

Brian

 

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Brian Brazil

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[emai...@gmail.com]

What about adding maximum as a property of a Summary i.e. <basename>_maximum?

Or can we set a bucket of 1.0 and get the same thing?

On Monday, 14 August 2017 15:19:15 UTC+1, Brian Brazil wrote:

[Brian Brazil]

On 15 August 2017 at 16:48, <emai...@gmail.com> wrote:

What about adding maximum as a property of a Summary i.e. <basename>_maximum?

That has the same fundamental problems.

Or can we set a bucket of 1.0 and get the same thing?

I'm not sure how accurate that will be.

Brian 

On Monday, 14 August 2017 15:19:15 UTC+1, Brian Brazil wrote:

On 14 August 2017 at 14:47, adamdougal <barmy...@gmail.com> wrote:

Hey, 

I'm currently using a histogram to record application response times. I'd like to keep track of the maximum value but can't see that as an option. Is there anything else I can use or can this be added?

I've used DropWizard metrics in the past which supports this http://metrics.dropwizard.io/3.2.3/getting-started.html#histograms

This isn't supported. The fundamental problem is the maximum over what time period? In Prometheus you are meant to be able to calculate over any time period, and thus there's no way to make this work sanely.

--

Brian Brazil

www.robustperception.io

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Brian Brazil

www.robustperception.io

[Björn Rabenstein]

In a Summary, you can set a objective for 1.0 or 0.0 (for the max or
min, respectively), but as Brian mentioned, the semantics might not be
what you expect. In the case of the Summary, you'll get the max or min
over MaxAge, as defined in the SummaryOpts, i.e. it's something set by
the monitored target and cannot be changed in the PromQL expression.

Surely, you can use 1.0 or 0.0 in the histogram_quantile call, but the
accuracy is determined by your bucket layout.


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