JEP 158: Unified JVM logging

Kirk Pepperdine kirk at kodewerk.com
Wed Aug 15 13:49:13 UTC 2012


On 2012-08-15, at 3:28 PM, Dmitry Samersoff <Dmitry.Samersoff at oracle.com> wrote:

> Kirk,
> 
> On 2012-08-15 12:56, Kirk Pepperdine wrote:
>> I should have added that Neal Ford has an excellent talk on taxonomy systems and tags vs. hierarchies. 
>> It includes a bit on the 5 kingdoms that all organisms are split into. Yet many organisms show characteristics 
>> from more than one kingdom while some others show characteristics of none. Problem is, 
>> the current hierarchical system forces categorization in a way that doesn't work where 
>> as a tag system would easily be able to cope. I'm trying to find a link to the talk.
> 
> Really good talk.
> 
> Stepping aside from logging problem -
> 
> hierarchy require additional efforts from a people who builds hierarchy,
> but tags put the same efforts to people who uses it.
> 
> If I'm constructing new butterfly and check description of Insecta,
> Lepidoptera I should get a list of the most important characteristics of
> all butterflies. It's responsibility of persons building hierarchy to
> create this list. I trust them and believe that if I give all these
> characteristics to my being it become a butterfly.

I think the point of Neal's talk is this type of taxonomy is better suited to tags. As you mentioned, a butterfly has wings.. but so do bees.. and birds.. and bats. So maybe not such a good idea to use wings a differentiator in a hierarchy. But as a tag it works out very well. A taxonomy for butterflies would simply include all the relevant tags.

> 
> But with tags I should build the list of characteristics by my self,
> e.g. start from insects with tags "four wings", and then refine the mix
> of Lepidoptera and Hymenoptera using other tags to distinguish between
> butterfly and bees.
> 
> So tags give you more power but require much more efforts in regular case.

I guess what I've also implicitly said is that the current GC logging system is essentially tag based. My feeling is that tags could be cleaned up which means I could probably get everything that I might want in about a dozen flags or less. I don't really want to get into an implementation discussion so lets just call the following a bad implementation and go from there.

java -log:gc,pauseTime,tenuring,stoppedTime,occupancyConfiguredSize,tag5,tag6  my.main

This seems about the same amount of effort as it to log today which isn't insignificant but it's also not a big burden that it's worth the loss of flexibility that is currently enjoyed. And again, tags don't preclude someone defining hierarchies of tags if that makes sense to they way their component works.

-- Kirk


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