RFR (S) JDK-8007725 - Klass::restore_unshareable_info() triggers assert(k->java_mirror() == NULL)

[Ioi Lam]

Hi Harold,

I used the "if" so that it would be easier to comment about the condition.

In product build, the "if" block would be eliminated by the compiler. I 
verified that in the Linux build.

Thanks
- Ioi

On 03/14/2013 06:58 AM, harold seigel wrote:
> Hi Ioi,
>
> You could simplify this in method.cpp from:
>
>     + if (!DumpSharedSpaces) {
>     +   // _method_data may be NULL if link_method failed due to OOM.
>     + } else {
>          assert(_method_data == NULL, "unexpected method data?");
>     + }
>     set_method_data(NULL);
>
> to something like:
>
>     assert(!DumpSharedSpaces || _method_data == NULL, "unexpected
>     method data?");
>     set_method_data(NULL);
>
> Then the DumpSharedSpaces flag is only checked if the assert is processed.
>
> Harold
>
> On 3/14/2013 9:46 AM, Coleen Phillimore wrote:
>>
>> This looks good.   Thank you for fixing it.
>> Coleen
>>
>> On 03/14/2013 01:49 AM, Ioi Lam wrote:
>>> Hi, could someone review this? This fixes a crash related to OOM 
>>> handling.
>>>
>>> Thanks
>>> - Ioi
>>>
>>> On 03/11/2013 12:47 PM, Ioi Lam wrote:
>>>> Please review:
>>>> http://cr.openjdk.java.net/~iklam/8007725/null_mirror_001/
>>>>
>>>> Bug: NPG: Klass::restore_unshareable_info() triggers
>>>>     assert(k->java_mirror() == NULL)
>>>>
>>>> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8007725
>>>>  or https://jbs.oracle.com/bugs/browse/JDK-8007725
>>>>
>>>>     (The bugs.sun.com page may be unavailable for a couple of days due
>>>>      to recent change of confidentiality status.)
>>>>
>>>> Summary of fix:
>>>>
>>>>     The assert is at:
>>>>
>>>>     --------
>>>>     # Internal Error (src/share/vm/classfile/javaClasses.cpp:527)
>>>>     # assert(k->java_mirror() == NULL) failed: should only assign 
>>>> mirror once
>>>>     java_lang_Class::create_mirror(KlassHandle)
>>>>     Klass::restore_unshareable_info()
>>>>     InstanceKlass::restore_unshareable_info()
>>>>     instanceKlassHandle 
>>>> SystemDictionary::load_shared_class(instanceKlassHandle,Handle)
>>>>     --------
>>>>
>>>>     This happens if during class loading, an OOM happened after
>>>>     Klass::restore_unshareable_info() has called
>>>>     java_lang_Class::create_mirror(), but before the class loading 
>>>> is completed.
>>>>
>>>>     At this point, the class is not in the system dictionary. 
>>>> However the
>>>>     Klass structure is partially initialized.
>>>>
>>>>     If the app tries to load the same class again, the assert happens.
>>>>
>>>>     The fix is to undo all work performed by
>>>>     InstanceKlass::restore_unshareable_info().
>>>>
>>>> Tests executed:
>>>>
>>>>     * JPRT
>>>>     * JCK (vm, lang, api/signaturetest)
>>>>     * UTE (vm.quick.testlist, )
>>>>
>>>> Thanks,
>>>> Ioi
>>>
>>
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/attachments/20130314/e8dbb4f9/attachment-0001.html