Small change to the -verbosegc output (CMS)

[kirk]

Hi Tony,

Nice change but if we are going to break something can we go a wee bit 
more whole hog on it? How about GC be changed to CMS? Make the awk 
parsing even easier. And trust me, I've no problems if you broke the 
entire logging system.. if it were more easily machine readable ;-)

Regards,
Kirk

Tony Printezis wrote:
> Hi all,
>
> For a while now, the initial-mark / remark pauses were not tagged 
> correctly on the CMS logs obtained with -verbosegc:
>
> 8.012: [ParNew 84832K->79546K(162816K), 0.0293764 secs]
> 8.043: [GC 79546K(162816K), 0.0004823 secs]
> 8.140: [ParNew 89658K->84364K(162816K), 0.0271073 secs]
> 8.673: [ParNew 94476K->86063K(162816K), 0.0254789 secs]
> 9.276: [GC 93707K(162816K), 0.0369005 secs]
> 9.426: [ParNew 83265K->74974K(162816K), 0.0217100 secs]
> 9.830: [ParNew 85086K->76329K(162816K), 0.0062086 secs]
>
> Above, the pauses at 8.043 and 9.276 are an initial-mark / remark 
> respectively, but novice users would never guess that this is the 
> case. We are proposing a small change to make the CMS -verbosegc 
> output clearer, which is the following:
>
> 8.012: [ParNew 84832K->79546K(162816K), 0.0293764 secs]
> 8.043: [GC (initial-mark) 79546K(162816K), 0.0004823 secs]
> 8.140: [ParNew 89658K->84364K(162816K), 0.0271073 secs]
> 8.673: [ParNew 94476K->86063K(162816K), 0.0254789 secs]
> 9.276: [GC (remark) 93707K(162816K), 0.0369005 secs]
> 9.426: [ParNew 83265K->74974K(162816K), 0.0217100 secs]
> 9.830: [ParNew 85086K->76329K(162816K), 0.0062086 secs]
>
> The downside is that your (awk-based?) parser might have to be 
> slightly modified to deal with the change. The good news are that the 
> logs will be more readable and your parser will now know what to do 
> when it comes across such pauses. I opened a CR for this (6916659):
>
> http://bugs.sun.com/view_bug.do?bug_id=6916659
>
> Are there any major objections to making this change?
>
> Yes, we do recommend folks to use -XX:+PrintGCDetails instead of 
> -verbosegc, as it will produce a much more detailed and helpful output 
> (and don't forget -XX:+PrintGCTimeStamps!!!). But, given that 
> -verbosegc is there anyway, might as well fix it.
>
> Regards,
>
> Tony, HS GC Group
>
>
>