Deferral justification: JDK-8022892

Tao Mao tao.mao at oracle.com
Wed Aug 14 20:42:47 PDT 2013


I'd like to take back one sentence. Please see inline. Thanks.
Tao

On 8/14/13 6:53 PM, Tao Mao wrote:
> 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.
The Microsoft support webpage says "Microsoft Windows Server 2008 R2 
Enterprise Edition" has a RAM limit of 2TB.
>
> 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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