Deferral justification: JDK-8022892

Tao Mao tao.mao at oracle.com
Wed Aug 14 18:53:41 PDT 2013


Hi GC team,

The CR is here https://jbs.oracle.com/bugs/browse/JDK-8022892.

First of all, Jon pointed out it's not a regression in hs24 since it 
reported against hs23. (Thank you, Jon) I think this is right. But i'm 
not sure, only with that, whether I can get through the deferral process.

So, let me put down what I have found so far.

1. In the CR,  Exception Code:c0000005 is seen and it means 
EXCEPTION_ACCESS_VIOLATION. This type of error is reported many times in 
different places inside and outside VM. Also, in the CR, it shows " 
Fault Module Name:msvcr100.dll", which indicates the top of stack frame 
is C native code/3rd party library from Microsoft. Thus, it may be not a 
VM problem at all, in this case.

2. Let's look at the ILW priority mapping. The impact is high since it's 
crash.

But there's ambiguity about its likelihood and workaround. I would think 
the likelihood is low according to the definition 
(http://wiki.se.oracle.com/display/JPGRM/ILW+and+priority+mapping+for+bugs#ILWandprioritymappingforbugs-DefectClassification) 


" The defect is encountered in an uncommon (or unsupported) use case or 
is intermittent in nature with a low frequency of occurrence"

Starting with initial heap size 140GB seems to be an uncommon use case 
(to me).

Workaround: use other collector as the report stated or lower heap size. 
Low.

ILW = HLL = P4.

3. In fact, it's hard to find a windows machine configured with 140GB 
memory. Probably there's no such machine if you refer to RAM/CPU limits 
of Windows machine stated in Microsoft website 
(http://support.microsoft.com/kb/2860880). The RAM limit for Windows HPC 
Server 2008 R2 is 128GB. That's the reason why I think the likelihood is 
low.

What I'm trying to do here is to use the Linux machine 
sthdev05.se.oracle.com listed here 
(http://wiki.se.oracle.com/display/JRPG/Development+Servers). This 
machine have about 256GB memory. But the VM cannot allocate(commit) 
enough memory if I set -Xms to be 35g or higher. In this attempt, we are 
not yet close to reproducing.

Ok, that's all I've found.

Among all these, I'd like to add the 128GB RAM limit of this type of 
Windows server as the second justification.

Could you read the email and look through the bug report to help obtain 
at least one more evidence for the deferral justification if possible?

Thanks.
Tao


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