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

[Bengt Rutisson]

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/

Thanks,
Bengt