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From Ivan Rakov <ivan.glu...@gmail.com>
Subject Re: [DISCUSSION][IEP-35] Metrics configuration
Date Mon, 05 Aug 2019 17:21:05 GMT
Hi guys,

DataStorageConfiguration#getMetricsSubIntervalCount was added by me as 
last resort to decrease number of intervals in HitRateMetrics in case of 
unexpected negative performance impact. As far as I know, no one ever 
used it - the precaution appeared to be premature. We can disregard its 
presence in DataStorageConfiguration.
 From my point of view, there's no need to change intervals count in 
runtime - it affects only metric smoothness and should be chosen by 
developer who understands details of metric implementation.

Regarding metrics configuration change management: if we are going to 
add it to the product, it should be user friendly (persistent and 
changeable in the whole cluster by single toggle, at least). Needing to 
change configuration at every cluster node after every cluster restart 
would irritate user more than provide help. Only very hacky cluster 
admin will be able to deal with current solution.
Distributed Metastorage is a good candidate for storing and handling 
such configuration options.

Best Regards,
Ivan Rakov

On 05.08.2019 18:38, Nikolay Izhikov wrote:
> Hello, Andrey.
>
>> Not necessary if we have exponential bounds' values for histograms.
> What do you mean by "exponential bounds"?
>
>> Anyway, in current solution it looks ugly and not usable.
> Thanks, for the feedback, appreciate you ownesty.
>
>> No. But we should admit that this is bad decision and do not include this change
to the code base.
> What is your proposal?
> How metrics configuration should work?
>
>> Yes. But it still will not give enough accuracy.
> Enough for what?
>
> В Пн, 05/08/2019 в 18:29 +0300, Andrey Gura пишет:
>>>> - metric configuration is node local (not cluster wide).
>>> This issue is easy to solve on the user-side and in Ignite core.
>> It's imaginary simplicity. The first, you need some additional
>> automation on user-side in order to configure all nodes of the
>> cluster. The second, new nodes can join to the cluster and
>> configuration will be different on new node and on other nodes of the
>> cluster. This leads to complication whole functionality. Anyway, I
>> don't like such simplified solution because at the moment it brings
>> more problems than value.
>>
>>> The easiest solution was implemented.
>>> Do we want to make it more complex right now :)?
>> No. But we should admit that this is bad decision and do not include
>> this change to the code base.
>>
>>> The reason it exists in PR - we already have this parameter in DataStorageConfiguration#getMetricsSubIntervalCount
>> I believe this method should be deprecated and removed in major release.
>>
>>> I think the user should be able to configure buckets for histogram and rateTimeInterval
for hitrate.
>> Not necessary if we have exponential bounds' values for histograms.
>> Anyway, in current solution it looks ugly and not usable.
>>
>>> Ignite has dozens of use-cases and deployment modes, seems,
>>> we can't cover it all with the single predefined buckets/rateTimeInterval set.
>> Yes. But it still will not give enough accuracy.
>>
>> On Mon, Aug 5, 2019 at 5:25 PM Nikolay Izhikov <nizhikov@apache.org> wrote:
>>> Hello, Andrey.
>>>
>>>> - metric configuration is node local (not cluster wide).
>>> This issue is easy to solve on the user-side and in Ignite core.
>>>
>>>> - metric configuration doesn't survive node restart.
>>> We decide to go with the simplest solution, for now.
>>> The easiest solution was implemented.
>>> Do we want to make it more complex right now :)?
>>>
>>>> - User shouldn't configure hit rate metrics at runtime in most cases.
>>> I agree with you - the size of the counters array looks odd as a configuration
parameter.
>>> The reason it exists in PR - we already have this parameter in DataStorageConfiguration#getMetricsSubIntervalCount
>>>
>>>> - May be it is enough for user to have histograms with pre-configured buckets
>>>> So I think we should drop this change and idea about runtime histrogram and
hit rate configuration.
>>> I think the user should be able to configure buckets for histogram and rateTimeInterval
for hitrate.
>>>
>>> Ignite has dozens of use-cases and deployment modes, seems,
>>> we can't cover it all with the single predefined buckets/rateTimeInterval set.
>>>
>>> В Пн, 05/08/2019 в 16:59 +0300, Andrey Gura пишет:
>>>> Igniters,
>>>>
>>>> I've took a look to the PR and I want follow up this discussion again.
>>>>
>>>> Proposed solution has a couple of significant drawbacks:
>>>>
>>>> - metric configuration is node local (not cluster wide).
>>>> - metric configuration doesn't survive node restart.
>>>>
>>>> This drawbacks make configuration complex, annoying and useless in most cases.
>>>>
>>>> Moreover, I think that:
>>>>
>>>> - User shouldn't configure hit rate metrics at runtime in most cases.
>>>> Especially HitRateMetric.size because it's just details of
>>>> implementation. Purpose of size is plots smoothing and this parameter
>>>> could be fixed (e.g. 16 is enough). HitRate metric is just LongMetric
>>>> but with additional feature.
>>>> - May be it is enough for user to have histograms with pre-configured
>>>> buckets. The trick here is properly chosen bounds. It seems that
>>>> exponentially chosen values will fit for most cases. So we can avoid
>>>> runtime configuration for histograms.
>>>> - We can also provide percentile metric for more accurate
>>>> measurements. Yes, it will bring additional performance impact and
>>>> accuracy will not be the best. But it will more clearly and will not
>>>> require configuration.
>>>>
>>>> So I think we should drop this change and idea about runtime
>>>> histrogram and hit rate configuration.
>>>>
>>>> Thoughts?
>>>>
>>>> On Tue, Jul 9, 2019 at 2:06 PM Nikolay Izhikov <nizhikov@apache.org>
wrote:
>>>>> Igniters,
>>>>>
>>>>> I made a PR for metrics configuration.
>>>>>
>>>>> Please, review
>>>>>
>>>>> https://github.com/apache/ignite/pull/6676/files
>>>>>
>>>>> В Вт, 09/07/2019 в 12:27 +0300, Nikolay Izhikov пишет:
>>>>>> Hello, Alex.
>>>>>>
>>>>>> OK, Let's go with the simplest solution.
>>>>>> I will provide API and JMX method for metrics configuration shortly.
>>>>>>
>>>>>> В Пн, 08/07/2019 в 18:23 +0300, Alexey Goncharuk пишет:
>>>>>>> Nikolay,
>>>>>>>
>>>>>>> To me a separate metrics configuration file seems to be not very
>>>>>>> user-friendly. First of all, it does not allow to configure the
system only
>>>>>>> from Java code. Second, having multiple configuration files seem
to be
>>>>>>> quite confusing for end users (judging by the logging configuration
>>>>>>> questions).
>>>>>>>
>>>>>>> Perhaps, we will still end up with the configuration file - but
for now I
>>>>>>> would put this aside for a more thorough brainstorm and added
the JMX and
>>>>>>> internal API for changing metrics configuration.
>>>>>>>
>>>>>>> пт, 5 июл. 2019 г. в 14:17, Seliverstov Igor <gvvinblade@gmail.com>:
>>>>>>>
>>>>>>>> Igniters,
>>>>>>>>
>>>>>>>> One more question on topic.
>>>>>>>>
>>>>>>>> Should we preserve metrics configuration on restart? (I think
we should)
>>>>>>>>
>>>>>>>> If so, which configuration use after restart? Defined in
config file or
>>>>>>>> saved in config storage? (I guess, saved configuration should
have a
>>>>>>>> priority)
>>>>>>>>
>>>>>>>> So, how to tell users that any changes in configuration file
have no
>>>>>>>> effect on Ignite configuration after first start?
>>>>>>>>
>>>>>>>> I think there are too many open questions and (at least at
now) we should
>>>>>>>> provide only JMX API until all of the questions are clarified.
>>>>>>>>
>>>>>>>> Regards,
>>>>>>>> Igor
>>>>>>>>
>>>>>>>>> 4 июля 2019 г., в 19:55, Nikolay Izhikov <nizhikov@apache.org>
>>>>>>>> написал(а):
>>>>>>>>> Hello, Andrey.
>>>>>>>>>
>>>>>>>>>> 3. I can't imagine that adequate values will be chosen
on project
>>>>>>>>>> setup stage.
>>>>>>>>> Configuration file required in the case we adds new node
or replace
>>>>>>>> existing to the cluster.
>>>>>>>>> Use can have parameters similar to Ignite configuration,
log
>>>>>>>> configuration files.
>>>>>>>>>> My proposal is adding API for boundaries configuration
to the metrics
>>>>>>>>>> framework and expose it via JMX
>>>>>>>>> Agree. I think we should have both:
>>>>>>>>>
>>>>>>>>> 1. Configuration file.
>>>>>>>>> 2. JMX API to change bounaries of histogram *and HitRateMetric
params*.
>>>>>>>>>
>>>>>>>>> But, if you and other community member are against config
file, let's
>>>>>>>> have only JMX.
>>>>>>>>> Seems, JMX will provide required level of configurability
for metrics.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> В Чт, 04/07/2019 в 17:53 +0300, Andrey Gura пишет:
>>>>>>>>>> Igniters,
>>>>>>>>>>
>>>>>>>>>> I rethought the issue and I see some problems:
>>>>>>>>>>
>>>>>>>>>> 1. It seems that in most cases bucket boundaries
configuration will be
>>>>>>>>>> problem for user. Absolute values for latency boundaries
it is very
>>>>>>>>>> odd choice.
>>>>>>>>>> 2. Also seems that latency for most caches (if we
configure cache
>>>>>>>>>> metrics fro example) will be similar.
>>>>>>>>>> 3. I can't imagine that adequate values will be chosen
on project
>>>>>>>>>> setup stage. So chosen values should be changed in
the future.
>>>>>>>>>>
>>>>>>>>>> Solution with configuration file looks unnatural
and creates more
>>>>>>>>>> problems than could solve.
>>>>>>>>>>
>>>>>>>>>> My proposal is adding API for boundaries configuration
to the metrics
>>>>>>>>>> framework and expose it via JMX (at this step). It
still provides
>>>>>>>>>> configuration possibility but don't force user to
do it.
>>>>>>>>>>
>>>>>>>>>> Also we should chose default values for bucket boundaries.
And it is
>>>>>>>>>> most complex problem at the moment :) Let's discuss
it.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On Wed, Jul 3, 2019 at 4:49 PM Andrey Gura <agura@apache.org>
wrote:
>>>>>>>>>>> Nikolai,
>>>>>>>>>>>
>>>>>>>>>>> Metric is disabled if it doesn't allocate any
memory and doesn't
>>>>>>>>>>> update any variable because doesn't have any
value. Ideally disabling
>>>>>>>>>>> metrics for some cache should be equal to cache
stopping.
>>>>>>>>>>>
>>>>>>>>>>> On Fri, Jun 28, 2019 at 1:02 PM Nikolay Izhikov
<nizhikov@apache.org>
>>>>>>>> wrote:
>>>>>>>>>>>> Hello, Alexey.
>>>>>>>>>>>>
>>>>>>>>>>>> Thanks for the feedback!
>>>>>>>>>>>>
>>>>>>>>>>>>> My only concert is that we should have
the metrics framework
>>>>>>>> configuration
>>>>>>>>>>>>> as the first-citizen of the framework
itself
>>>>>>>>>>>> Yes. I planned to add `void configure(String
param)` method to the
>>>>>>>> metric API.
>>>>>>>>>>>>> but change the metrics parameters in
>>>>>>>>>>>>> runtime from JMX or command-line, etc.
>>>>>>>>>>>> I've add requirement of JMX method to the
ticket:
>>>>>>>>>>>>
>>>>>>>>>>>> https://issues.apache.org/jira/browse/IGNITE-11927
>>>>>>>>>>>>
>>>>>>>>>>>>> Another concern is to have an
>>>>>>>>>>>>> ability to disable/enable metrics per
metrics group/prefix.
>>>>>>>>>>>> Yes, we discusss it.
>>>>>>>>>>>> But, let's make it clear:
>>>>>>>>>>>>
>>>>>>>>>>>> *What is disabling metric?*
>>>>>>>>>>>>
>>>>>>>>>>>> Looks like exporter filter solve this task.
>>>>>>>>>>>>
>>>>>>>>>>>> В Чт, 27/06/2019 в 16:24 +0300, Alexey
Goncharuk пишет:
>>>>>>>>>>>>> Nikolay,
>>>>>>>>>>>>>
>>>>>>>>>>>>> My only concert is that we should have
the metrics framework
>>>>>>>> configuration
>>>>>>>>>>>>> as the first-citizen of the framework
itself. This way, we can
>>>>>>>> configure
>>>>>>>>>>>>> the metrics not only from file, but change
the metrics parameters in
>>>>>>>>>>>>> runtime from JMX or command-line, etc.
Another concern is to have an
>>>>>>>>>>>>> ability to disable/enable metrics per
metrics group/prefix.
>>>>>>>>>>>>>
>>>>>>>>>>>>> The logger-like configuration meets these
suggestions given that the
>>>>>>>>>>>>> configuration is generalized into the
metrics framework.
>>>>>>>>>>>>>
>>>>>>>>>>>>> What do you think?
>>>>>>>>>>>>>
>>>>>>>>>>>>> чт, 27 июн. 2019 г. в 12:30, Nikolay
Izhikov <nizhikov@apache.org>:
>>>>>>>>>>>>>
>>>>>>>>>>>>>> Hello, Igniters.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> As you may know, I've contributed
Phase1 [1] for IEP-35 [2].
>>>>>>>>>>>>>> Now we have metrics subsystem and
can create and export any metrics
>>>>>>>> from
>>>>>>>>>>>>>> Ignite.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I think user(administrator of Ignite)
should be able to configure
>>>>>>>> some
>>>>>>>>>>>>>> metrics params in a common way [3]
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I propose to use the same way from
logging frameworks.
>>>>>>>>>>>>>> We should define some file format
Ignite can understand.
>>>>>>>>>>>>>> An administrator fills configuration
file to configure one or
>>>>>>>> several
>>>>>>>>>>>>>> metrics.
>>>>>>>>>>>>>> Ignite will analyze the file and
use provided params during metrics
>>>>>>>>>>>>>> creation.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> For now, we have 2 types of metrics
that should be configured:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>         *       HistrogramMetric
[4]
>>>>>>>>>>>>>>                 This metric is a
count of measurement that falls into
>>>>>>>>>>>>>> predefined intervals.
>>>>>>>>>>>>>>                 An example is "Request
processing time distribution".
>>>>>>>>>>>>>>                 We want to calculate
a count of requests processed
>>>>>>>> quicker
>>>>>>>>>>>>>> then 50ms, 50-100, 100-250, 250-500
and slower.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>         *       HitRateMetric [5]
>>>>>>>>>>>>>>                 This metric is a
count of events in the last time
>>>>>>>> interval.
>>>>>>>>>>>>>>                 An example is the
"Count of requests processed in
>>>>>>>> the last
>>>>>>>>>>>>>> 5 seconds".
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Example of file content:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> ````
>>>>>>>>>>>>>> cache.my-cahe.GetLatency=50,100,250,500
#Params for the histogram
>>>>>>>> metric
>>>>>>>>>>>>>> with the name `cache.my-cahe.get`
>>>>>>>>>>>>>> cache.my-cache.RebalancingKeysRate=60000
#Param for existing
>>>>>>>> HitRateMetric
>>>>>>>>>>>>>> that hold "Estimated rebalancing
speed in keys".
>>>>>>>>>>>>>> ````
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Please, share your vision.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> [1]
>>>>>>>>>>>>>>
>>>>>>>> https://github.com/apache/ignite/commit/fdaa310430aefff07994eb35510d3416886b5bbe
>>>>>>>>>>>>>> [2]
>>>>>>>>>>>>>>
>>>>>>>> https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=112820392
>>>>>>>>>>>>>> [3] https://issues.apache.org/jira/browse/IGNITE-11927
>>>>>>>>>>>>>> [4]
>>>>>>>>>>>>>>
>>>>>>>> https://github.com/apache/ignite/blob/master/modules/core/src/main/java/org/apache/ignite/internal/processors/metric/impl/HistogramMetric.java
>>>>>>>>>>>>>> [5]
>>>>>>>>>>>>>>
>>>>>>>> https://github.com/apache/ignite/blob/master/modules/core/src/main/java/org/apache/ignite/internal/processors/metric/impl/HitRateMetric.java
>>>>>>>>

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