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From: Yaroslav Skopets <y.skopets@gmail.com>
Date: Sun, 1 Oct 2017 11:24:17 +0200
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Subject: Re: Do you have any plans to instrument `log4j2` with metrics?
To: Log4J Users List <log4j-user@logging.apache.org>
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archived-at: Sun, 01 Oct 2017 09:24:34 -0000

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Thanks a lot already!

@Ralph

Besides `AsyncAppender`, other good candidates for instrumentation would be
`BurstFilter` and `DefaultErrorHandler`.

Another angle to this are custom plugins. E.g., we've got our own
`RedisAppender` that is guarded by a rate limit, a throughput limit, etc.
And while we would like to expose how those limits work out in practice, we
don't see examples/guidelines in `log4j2` code.

By the way, how could we integrate our own plugin with JMX ? So that it
would be registered/unregistered at the same time as components provided
out-of-the-box.

@Remko

Regarding performance of counters, I've just double checked that both
`Dropwizard` and `Prometheus` address this problem by including a copy of
JDK 8 `LongAdder`/`DoubleAdder` into their own codebase (e.g.,
https://github.com/dropwizard/metrics/blob/3.2-development/metrics-core/src=
/main/java/com/codahale/metrics/LongAdder.java#L37
 and
https://github.com/prometheus/client_java/blob/master/simpleclient/src/main=
/java/io/prometheus/client/DoubleAdder.java#L35
)

So, may be `log4j2` could introduce a notion of `AdderFactory` and use it
for counters and gauges?


On Sun, Oct 1, 2017 at 3:09 AM, Remko Popma <remko.popma@gmail.com> wrote:

> Ralph beat me to it. :-)
>
> We could add counters to various components and make those counters
> visible via JMX. Surely the libraries you mention know how to consume
> metrics from a JMX data source.
>
> To me a key point would be to avoid impacting performance while updating
> counters in multi-threaded situations.
>
> Patches are welcome!
>
> Remko
>
> (Shameless plug) Every java main() method deserves http://picocli.info
>
> > On Oct 1, 2017, at 10:00, Ralph Goers <ralph.goers@dslextreme.com>
> wrote:
> >
> > Development of Log4j happens based on a) what committers are interested
> in doing or b) patches that are submitted by users.  Sometimes we discuss
> things we want to develop in advance but most of the time we decide to do
> something and just do it.
> >
> > You are the first person to ask for metrics from the AsyncAppender. We
> already have a JMX component so I would imagine reporting of those metric=
s
> would be integrated with that if it was implemented.
> >
> > I=E2=80=99ve not heard anyone mention integrating with those 3 librarie=
s.
> >
> > As I noted above, patches are always welcome!
> >
> > Ralph
> >
> >
> >> On Sep 30, 2017, at 4:16 PM, Yaroslav Skopets <y.skopets@gmail.com>
> wrote:
> >>
> >> Hi guys,
> >>
> >> I was going through the source code of `log4j2` and didn't notice any
> >> metrics that could tell how the system is doing.
> >>
> >> Most importantly, classes like `AsyncAppender` might just silently dro=
p
> >> errors instead of making such incidents noticeable.
> >>
> >> So, do you have any plans to introduce metrics for those cases? And,
> >> ideally, provide bindings to libraries like `Dropwizard`, `Prometheus`=
,
> >> `Micrometer` ?
> >>
> >> Thanks in advance!
> >>
> >> --
> >> Best regards,
> >> Yaroslav Skopets
> >
> >
> >
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>


--=20
Best regards,
Yaroslav Skopets

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