Will parsers break if we start logging the GC cause as part of the PrintGC logging?

[Bengt Rutisson]

Hi Vitaly,

On 2012-05-07 23:24, Vitaly Davidovich wrote:
>
> Hi Bengt,
>
> Another option would be to enable the extra logging/new format via a 
> VM argument? I know there are already tons of them so this is probably 
> undesirable, but may provide at least a transition period for 
> customers to upgrade their parsers.
>

Agreed, but I would really like to avoid more VM arguments. If we feel 
uncomfortable with this change I think we should just not do it at this 
point in time.

There is a project in planning for a more general logging framework for 
Hotspot. Once that is in place I am sure we will do a major update to 
the GC logging. At that time I guess many parsers will break, so if we 
feel that the proposed change is high risk at the moment I think we 
should postpone it to the major logging overhaul.

I know there has been a JEP written for the new logging framework but 
that JEP is still awaiting publication. Hopefully it will be available soon.

Thanks,
Bengt

> Sent from my phone
>
> On May 7, 2012 5:19 PM, "Bengt Rutisson" <bengt.rutisson at oracle.com 
> <mailto:bengt.rutisson at oracle.com>> wrote:
>
>
>     Hi all,
>
>     I have a webrev out for a change that will add the GC cause to all
>     "Full
>     GC logging". See:
>
>     http://permalink.gmane.org/gmane.comp.java.openjdk.hotspot.gc.devel/4527
>
>     The extra information was intentionally just added to full GCs since
>     this logging already had information for System.gc() calls so we
>     figured
>     that any parsers out there would have to handle this information
>     anyway.
>
>     It was requested to add the information about the GC cause also to CMS
>     collections. If I start down that path I think I could just as
>     well add
>     the GC cause to all GC logging. If we break any parsers we will
>     probably
>     break them already when we add the cause to CMS GCs.
>
>     Not sure what the best way to handle this is. Some suggestions:
>
>     (1) Only add cause to Full GCs (as in my change now)
>     (2) Only add cause to Full GCs and CMS GCs (as I think is what was
>     suggested)
>     (3) Add cause to all GCs (probably the proper but kind of risky way)
>     (4) Only do (1) but file CRs for (2) and (3)
>
>     Any thoughts? It is really a choice between getting interesting
>     information and risking breaking existing GC log parsers.
>
>     Here is the latest webrev:
>     http://cr.openjdk.java.net/~brutisso/7166894/webrev.01/
>     <http://cr.openjdk.java.net/%7Ebrutisso/7166894/webrev.01/>
>
>     Thanks,
>     Bengt
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