RFR(10)(XXS): 8175341: "java/util/Arrays/ParallelPrefix.java" Crash Internal Error ...diagnosticCommand.cpp...assert(k != __null) failed: FinalizerHistogram class is not accessible

[David Holmes]

On 7/03/2017 12:14 PM, Chris Plummer wrote:
> On 3/6/17 5:58 PM, David Holmes wrote:
>> On 7/03/2017 11:51 AM, David Holmes wrote:
>>> Hi Chris,
>>>
>>> On 7/03/2017 10:57 AM, Chris Plummer wrote:
>>>> Hi,
>>>>
>>>> Please review the following simple fix. Explanation of the cause and
>>>> the
>>>> fix are in the CR. Testing so far has only been done with
>>>> serviceability/dcmd/gc/FinalizerInfoTest.java as described in the CR. I
>>>> think the addition of JPRT push testing will be sufficient.
>>>>
>>>> http://cr.openjdk.java.net/~cjplummer/8175341/webrev.00/webrev.hotspot/
>>>> https://bugs.openjdk.java.net/browse/JDK-8175341
>>>
>>> Looking at the other potentially-exception-throwing actions in that DCmd
>>> and others, I think a simple delete of the assert and change:
>>>
>>>  425     vmSymbols::finalizer_histogram_klass(), THREAD);
>>>
>>> to
>>>
>>>  425     vmSymbols::finalizer_histogram_klass(), CHECK);
>>>
>>> would suffice. Something upstream has to handle potential errors and the
>>> pending exception in any case.
>>
>> Oops! This explains why no exception:
>>
>> 424   Klass* k = SystemDictionary::resolve_or_null(
>>  425     vmSymbols::finalizer_histogram_klass(), THREAD);
>>
>> it uses resolve_or_null, not resolve_or_fail! I think it should use
>> the latter and simply throw like the other Dcmds.
>>
> Ok. That seems to work. Bit of a hurry here before I step out, so
> trimmed diff is inline:
>
> -  Klass* k = SystemDictionary::resolve_or_null(
> -    vmSymbols::finalizer_histogram_klass(), THREAD);
> -  assert(k != NULL, "FinalizerHistogram class is not accessible");
> +  Klass* k = SystemDictionary::resolve_or_fail(
> +    vmSymbols::finalizer_histogram_klass(), true, CHECK);
> +  if (k == NULL) {
> +    return;
> +  }
>
> I'm a bit unclear about THREAD vs CHECK. They both seem to work. Not
> sure which is correct here.

THREAD is just a reference to the current thread (as passed down the 
call chain). CHECK automatically expands into a pending exception check 
plus a return. So your "if (k==null) ..." is unreachable with CHECK - as 
k will only be NULL if an exception is pending.

Thanks,
David

> When I forced an exception by dropping the last character of the class
> name, here's what I see in the test output:
>
>  stderr: [java.lang.NoClassDefFoundError: java/lang/ref/FinalizerHistogra
> ]
>
> cheers,
>
> Chris
>> David
>>
>>> Thanks,
>>> David
>>>
>>>> thanks,
>>>>
>>>> Chris
>>>>
>