RFR: JDK-8131600: heapdump/JMapHeap EXCEPTION_ACCESS_VIOLATION

Bengt Rutisson bengt.rutisson at oracle.com
Thu Jul 23 06:37:38 UTC 2015



On 2015-07-22 20:03, Kim Barrett wrote:
> On Jul 22, 2015, at 12:11 PM, Bengt Rutisson <bengt.rutisson at oracle.com> wrote:
>> On 2015-07-22 17:11, Kim Barrett wrote:
>>> On Jul 22, 2015, at 8:12 AM, Bengt Rutisson <bengt.rutisson at oracle.com> wrote:
>>>> Hi everyone,
>>>>
>>>> Could I have a couple of reviews for this patch to fix one of the critical nightly issues we are currently having?
>>>>
>>>> http://cr.openjdk.java.net/~brutisso/8131600/webrev.00/
>>>> https://bugs.openjdk.java.net/browse/JDK-8131600
>>>>
>>>> Background
>>>> […]
>>>> Now, DumperSupport::dump_class_and_array_classes() actually calls InstanceKlass::signers() twice. The second time around we don't have an InstanceKlass but just a Klass. The Klass does not have the is_linked() method. I haven't tried to provoke that code to fail, but I assume it has the same problem. So, I added a java_class() != NULL check to that code to make it handle this case as well.
>>> I think this change shouldn't be needed.
>>>
>>> The klass involved is the result of array_klass_or_null(). That
>>> shouldn't be able to return an incompletely initialized (array) klass.
>> Yes, I was discussing this a bit with Mikael and we weren't really sure. I think you are right, I'm just a bit worried about how fragile the class initialization seems to be.
>>
>> But I'll remove this part of the fix. Let's just keep our eyes open if a crash in this area comes up again.
> With that part backed out, change looks good to me.

Thanks, Kim!

Here's an updated webrev:
http://cr.openjdk.java.net/~brutisso/8131600/webrev.01/

Bengt


>



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