CRR (S): 7099849: G1: include heap region information in hs_err files

[Tony Printezis]

Poonam,

Hi and thanks for the feedback. Good suggestions. I'll implement them 
and send out an updated webrev.

Tony

On 11/1/2011 10:08 AM, poonam.bajaj at oracle.com wrote:
> Hi Tony,
>
> I hope I am not too late in providing feedback on this change. Here 
> are couple of suggestions for the heap regions information in hs_err file:
>
> - I think it would be useful to print a header before the heap regions 
> details. e.g.
>
> Heap
>  garbage-first heap   total 20480K, used 11630K [0x6e600000, 
> 0x6fa00000, 0xae600000)
>   region size 1024K, 1 young (1024K), 1 survivors (1024K)
>  compacting perm gen  total 16384K, used 2604K [0xae600000, 
> 0xaf600000, 0xb2600000)
>    the space 16384K,  15% used [0xae600000, 0xae88b3c0, 0xae88b400, 
> 0xaf600000)
> No shared spaces configured.
>
> *Heap Regions:*
>                   0 PTAMS 0x6e600000 NTAMS 0x6e639700 space 1024K,  
> 22% used [0x6e600000, 0x6e639700, 0x6e700000)
>           F    17 PTAMS 0x6e700000 NTAMS 0x6e700000 space 1024K,   0% 
> used [0x6e700000, 0x6e700000, 0x6e800000)
>           F    17 PTAMS 0x6e800000 NTAMS 0x6e800000 space 1024K,   0% 
> used [0x6e800000, 0x6e800000, 0x6e900000)
>
>
> - Also, I think it would be helpful for the hs_err file reader to have 
> the meanings of the acronyms also printed (as we show in the stack 
> trace in hs_err file)
>
> Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, 
> C=native code)
> V  [libjvm.so+0xc494db]  VMError::report_and_die()+0x19b
>
> Heap Regions: (CS=collection set, PTAMS=previous top at mark start, 
> NTAMS=next top at mark start, etc...)
>                17 PTAMS 0x6f200000 NTAMS 0x6f300000 space 1024K, 100% 
> used [0x6f200000, 0x6f300000, 0x6f300000)
>     CS SU      17 PTAMS 0x6f300000 NTAMS 0x6f38e650 space 1024K,  55% 
> used [0x6f300000, 0x6f38e650, 0x6f400000)
>                17 PTAMS 0x6f400000 NTAMS 0x6f493c60 space 1024K,  57% 
> used [0x6f400000, 0x6f493c60, 0x6f500000)
>
>
>
> Thanks,
> Poonam
>
>
> On 10/12/2011 10:19 PM, Tony Printezis wrote:
>> Hi all,
>>
>> (I'm also copying the runtime alias, as this change will concern them 
>> too)
>>
>> I'd like to get a couple of reviews for this change:
>>
>> http://cr.openjdk.java.net/~tonyp/7099849/webrev.0/
>>
>> Some background: when trying to track down issues in G1 it is often 
>> very helpful to know what type of regions the heap has and/or get 
>> information on a particular region (whether it's humongous, whether 
>> it's young, how full it is, etc.). We thought it'd be a good idea to 
>> include the per-region information in the hs_err file to always have 
>> it available after a crash.
>>
>> I don't think the changes in the webrev are too controversial. The 
>> reason I wanted to give a heads up to both groups was to point out 
>> that this change will increase the size of the hs_err files when G1 
>> is used. It's common to have 1,000 to 2,000 regions in the heap, if 
>> larger heaps are used (much fewer if smaller heaps are used), which 
>> means that the hs_err file will have this many extra lines. Does 
>> anyone have any concerns about this?
>>
>> I attached an example hs_err file obtained from a workspace with this 
>> change applied.
>>
>> BTW, I also cleaned up a bit the way the print() methods on the heap 
>> are defined (I pushed the default behavior to the superclass, where 
>> possible).
>>
>> Tony
>>
>
> -- 
> Best regards, Poonam
>
> Oracle <http://www.oracle.com>
> Poonam Bajaj | Principal Member of Technical Staff
> Phone: +91 80 66937451 <tel:+91%2080%2066937451> | Mobile: +91 
> 9844511366 <tel:+91%209844511366>
> Oracle JVM Sustaining Engineering
>
> ORACLE India Bangalore
> Green Oracle <http://www.oracle.com/commitment> Oracle is committed to 
> developing practices and products that help protect the environment
>
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