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From Stuart Monteith <stuk...@stoo.me.uk>
Subject Re: Kato status (Was: Actively retiring projects)
Date Tue, 31 Jan 2012 16:36:28 GMT
On 27/01/12 14:22, Steve Poole wrote:
> Stuart - comments inlined...
>
> On Fri, Jan 27, 2012 at 12:15 AM, Stuart Monteith<stukato@stoo.me.uk>wrote:
>
>>
> >-8 snip
>>
>> 1. While the API is a good idea, there is no demand from the community.
>>
>
> I agree that is true now -  it wasn't when we started.
Yes - I think the answer is to produce something that would be in 
demand. Kato won't graduate without a viable community.

>
> 2. The target audience is very limited.
>>
>> 3. Oracle's resources are limited, and the JSR is targeted at a limited
>> audience.
>>
>> 4. Would need more feedback from the community - but wouldn't be done in
>> the JDK 8 time frame.
>>
>> We've been through the process of getting community feedback. The response
>> was generally positive. Steve can fill us in further.
>>
>
> The promise of the tools we put together did attract a lot of attention -
> the long delay in delivering them has obviously turned people off.
> The idea of the Java equivilent of  "dbx for corefiles" is always
> attractive.

Yes - I have my doubts though about making "dbx for corefiles" produce 
useful information and also have it reliable and have a low overhead. 
Obviously we'll exploit any improvements to JVM diagnostics as and when 
they come along.

>
>>
>> The target audience for the API was limited - tool vendors and JDK
>> support. The target audience for the tools that were to be based on the
>> Kato API were Java developers, support, and operations.
>>
>> My view is that while the API is an interesting concept, it is too low a
>> level for there ever to be community interest in it's development - there
>> are so few vendors. When we started this there was at least Sun, Oracle
>> (who had just bought BEA), Intel and IBM. Now we are reduced to Oracle and
>> IBM, which is a very small community indeed, and as they are both
>> cooperating somewhat through OpenJDK that is even smaller.
>>
>> Yes agreed.
>
>
>> I see us continuing in the following form:
>>
>>-8 snip
>>
>> I agree with all these points but I would point out that we said at the
> beginning of Kato that the JSR 326 spec would just "fall out" of the Kato
> implementation - ie a code lead spec.   That's still true so I think we
> should reserve judgement on the disconnection of JSR 326 from Kato.   I'd
> rather ignore it for now. We should just focus on producing the tools and
> supporting API we want and worry about any form of standardisation later.
 >

I agree - let's ignore the JSR for now. The API is now a means to an 
end, rather than a end in itself. The goal of the Kato project then 
changes to produce post-mortem debugging tooling, and other offline JVM 
debugging tooling.

I propose we should vote on changing the projects goals. We do want to 
be clear on what we are trying to achieve - otherwise people won't know 
if they should be interested.

>> Can we produce something that is compelling?
>>
>>-8 Snip
>> But is there anything else?
>>
>
> Creating a connector between jdi and a dump is good and useful since it
> makes use of a familiar interface.   I would like to go further and produce
> more comprehensive diagnostic tools that would not fit into the jdi model.
>
> I mentioned serialisation before as one example.  Take a serialisation
> stream and present it in a graphical view.  For deserialisation failures
> take a set of classes and a serialisation stream and show where and how the
> stream doesnt match the classes provided.    That one really bugs me. At my
> Serialisation talk at JavaOne last year I got a ton of people asking how to
> debug these sorts of problems.
>
> Other ideas :
>
> change or compliment the API with something more SAX style related (rather
> than the DOM style we have today)   and add a good query mechanism on
> top.
> Implement the snapshot dump API so that we can get smaller dumps.
> Create Eclipse plugins for these new things so that developers have a
> better experience than a command line tool.
>
> I'm sure I will think of others :-)
>

The modules we have for the CLI (i.e. Tomcat diagnosis) could be one 
approach. I still like the idea of FFDC tools that perform FFDC without 
having to explicitly store information that might be incomplete. I will 
have to rethink in more detail about what we have and how I'd like to 
contribute.


Regards,
     Stuart

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