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

[harold seigel]

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
>>
>

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