RFR(XS): 8209736: runtime/RedefineTests/ModifyAnonymous.java fails with NullPointerException when running in CDS mode
Jiangli Zhou
jiangli.zhou at oracle.com
Fri Aug 31 22:47:57 UTC 2018
> On Aug 31, 2018, at 2:54 PM, Calvin Cheung <calvin.cheung at oracle.com> wrote:
>
>
>
>> On 8/31/18, 1:52 PM, Jiangli Zhou wrote:
>> Hi Calvin,
>>
>>
>>> On 8/31/18 1:33 PM, Calvin Cheung wrote:
>>> Hi Jiangli,
>>>
>>>> On 8/31/18, 1:10 PM, Jiangli Zhou wrote:
>>>> Hi Calvin,
>>>>
>>>> How about use a separate loop (before the main test loop in runTest()) to print out the class names in the allLoadedClasses array?
>>> 109 static void runTest() {
>>> 110 while (!done) {
>>> 111 Class[] allLoadedClasses = inst.getAllLoadedClasses();
>>> 112 int len = allLoadedClasses.length;
>>> 113 for (int idx = 0; idx < len; idx++) {
>>>
>>> Did you mean print out all the class names after line 111? There would be too much output since there's a while loop enclosing it.
>>> Or did you mean something else?
>> Yes. If the failure does re-manifest again, we can compare the output with a normal run. That would give some useful information. How big is the allLoadedClasses?
> On my local linux machine, it only loops through the while loop twice and I saw more than 1800 class names in the output.
>>
>> Or, maybe we could print the classes if null is detected.
> This is a better option.
Probably dumping to a file.
>>>> If null is discovered, throw a RuntimeException(). That helps to provide more debugging information and also will not silent the issue that causes the NPE if it does' resurface again.
>>> I don't think throwing a RuntimeException() gives anymore info than the existing NPE.
>>> The idea of this change is that after a null clazz is encountered, let the test continue to run. It may fail in a different way which may give us more clues.
>> The NPE might be caused by a rare race condition, which might not affect the redefineClass process and the test could pass with the change. We should avoid such case.
> Maybe but we don't know for sure. The main purpose of the test is to make sure an anonymous class cannot be retransformed or redefined. So I don't think we're masking any problem if a null class is encountered and the test passed.
The issue is with getAllLoadedClasses. The proposed change would make the issue not being detected. I think we need to understand what’s the expected behavior of the API.
Thanks,
Jiangli
>
> thanks,
> Calvin
>>
>> Thanks,
>> Jiangli
>>>
>>> thanks,
>>> Calvin
>>>>
>>>> Thanks,
>>>>
>>>> Jiangli
>>>>
>>>>
>>>>> On 8/31/18 11:33 AM, Calvin Cheung wrote:
>>>>> bug: https://bugs.openjdk.java.net/browse/JDK-8209736
>>>>>
>>>>> webrev: http://cr.openjdk.java.net/~ccheung/8209736/webrev.00/
>>>>>
>>>>> The test failure is no longer reproducible; it happened only once in tier3 and once in tier6 testing.
>>>>> This simple change is just adding a null check on the variable clazz and prints the array size and index if it is null.
>>>>>
>>>>> Testing: hs-tier{1,2,3} with default CDS archive in JDK.
>>>>>
>>>>> thanks,
>>>>> Calvin
>>>>
>>
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