Code review request: 6855834: G1: minimize the output when -XX:+PrintHeapAtGC is set (S)

John Coomes John.Coomes at sun.com
Tue Jul 7 11:19:48 PDT 2009


Tony Printezis (Antonios.Printezis at Sun.COM) wrote:
> John,
> 
> New output below. Looks good?

Yes, I like it.  One nit, though:  I would remove the trailing comma
after the survivors size.

-John

> --------------
> 
> {Heap before GC invocations=12 (full 3):
>  garbage-first heap   total 26624K, used 22004K [0xf2400000, 0xf3e00000, 
> 0xf5400000)
>   region size 1024K, 16 young (16384K), 2 survivors (2048K),
>  compacting perm gen  total 16384K, used 3070K [0xf5400000, 0xf6400000, 
> 0xf9400000)
>    the space 16384K,  18% used [0xf5400000, 0xf56ffa68, 0xf56ffc00, 
> 0xf6400000)
> No shared spaces configured.
> 15.982: [GC pause (young) 21M->9990K(28M), 0.1216863 secs]
> Heap after GC invocations=13 (full 3):
>  garbage-first heap   total 28672K, used 9990K [0xf2400000, 0xf4000000, 
> 0xf5400000)
>   region size 1024K, 4 young (4096K), 4 survivors (4096K),
>  compacting perm gen  total 16384K, used 3070K [0xf5400000, 0xf6400000, 
> 0xf9400000)
>    the space 16384K,  18% used [0xf5400000, 0xf56ffa68, 0xf56ffc00, 
> 0xf6400000)
> No shared spaces configured.
> }
> {Heap before GC invocations=13 (full 3):
>  garbage-first heap   total 28672K, used 21584K [0xf2400000, 0xf4000000, 
> 0xf5400000)
>   region size 1024K, 16 young (16384K), 4 survivors (4096K),
>  compacting perm gen  total 16384K, used 3077K [0xf5400000, 0xf6400000, 
> 0xf9400000)
>    the space 16384K,  18% used [0xf5400000, 0xf57016b8, 0xf5701800, 
> 0xf6400000)
> No shared spaces configured.
> 16.570: [Full GC (System.gc()) 21M->566K(24M), 0.1898490 secs]
> Heap after GC invocations=14 (full 4):
>  garbage-first heap   total 24576K, used 566K [0xf2400000, 0xf3c00000, 
> 0xf5400000)
>   region size 1024K, 0 young (0K), 0 survivors (0K),
>  compacting perm gen  total 16384K, used 3075K [0xf5400000, 0xf6400000, 
> 0xf9400000)
>    the space 16384K,  18% used [0xf5400000, 0xf5700dd0, 0xf5700e00, 
> 0xf6400000)
> No shared spaces configured.
> }
> 
> 
> John Coomes wrote:
> > Tony Printezis (Antonios.Printezis at Sun.COM) wrote:
> >   
> >> http://cr.openjdk.java.net/~tonyp/6855834/webrev.0/
> >>
> >> The CR has more information on the new format:
> >>     
> >
> > Haven't reviewed the code yet (sorry), but have some questions.
> >
> > Does G1 have reasonably accurate occupancy info when this info is
> > printed?  If so, it would be nice to have a breakdown of the amount or
> > percentage used in young regions, survivor regions & old regions.
> > That would be closer to the info you get for the other collectors.
> >
> > If not, then I would combine the "region size" line with the one that
> > follows it.  Best shown by example:
> >
> > Change this:
> >
> >  garbage-first heap   total 24576K, used 16950K [0xf2400000, 0xf3c00000, 0xf5400000)
> >   region size 1024K
> >   young regions 16 / 16384K  survivor regions 0 / 0K
> >
> >
> > To something like this:
> >
> >  garbage-first heap   total 24576K, used 16950K [0xf2400000, 0xf3c00000, 0xf5400000)
> >   region size 1024K, 16 young (16384K), 1 survivor (1024K)
> >
> > -John
> >
> >   
> 
> -- 
> ----------------------------------------------------------------------
> | Tony Printezis, Staff Engineer    | Sun Microsystems Inc.          |
> |                                   | MS BUR02-311                   |
> | e-mail: tony.printezis at sun.com    | 35 Network Drive               |
> | office: +1 781 442 0998 (x20998)  | Burlington, MA01803-0902, USA  |
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