RFR: 8243290: Improve diagnostic messages for class verification and redefinition failures

[serguei.spitsyn at oracle.com]

+1

Thanks,
Serguei


On 6/10/20 08:17, Harold Seigel wrote:
> +1
>
> Thanks, Harold
>
> On 6/10/2020 10:36 AM, coleen.phillimore at oracle.com wrote:
>> Looks good to me now.
>> thanks,
>> Coleen
>>
>> On 6/10/20 9:06 AM, Poonam Parhar wrote:
>>> Hello Harold,
>>>
>>> Thanks for your review! I fixed the null string issue, and here's 
>>> the updated webrev:
>>> http://cr.openjdk.java.net/~poonam/8243290/webrev.01/
>>>
>>> Thanks,
>>> Poonam
>>>
>>> On 6/9/20 8:38 AM, Harold Seigel wrote:
>>>> Hi Poonam,
>>>>
>>>> Thanks for making this change.
>>>>
>>>> In verifier.cpp, if ex_msg is NULL, will the call to st->print_cr() 
>>>> at line 142 - 143, fail?
>>>>
>>>> Thanks, Harold
>>>>
>>>> On 6/9/2020 10:46 AM, Poonam Parhar wrote:
>>>>> Hello,
>>>>>
>>>>> Please review this simple change for improving diagnostics around 
>>>>> class verification and linking failures:
>>>>>
>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8243290
>>>>> Webrev: http://cr.openjdk.java.net/~poonam/8243290/webrev.00/
>>>>>
>>>>> Problem: During the class redefinition process, if a class 
>>>>> verification fails because it could not find a class referenced in 
>>>>> the class being redefined, the printed NoClassDefFoundError error 
>>>>> message is not very helpful. It does not print the class name for 
>>>>> which NoClassDefFoundError was encountered, and that makes it very 
>>>>> hard to find the real cause of redefinition failure.
>>>>>
>>>>> The proposed solution prints the class name during class linking 
>>>>> and verification failures. Example output produced with these 
>>>>> changes:
>>>>>
>>>>> With 'redefine' tag:
>>>>>
>>>>>      [java] [3.243s][debug][redefine,class,load        ] loaded 
>>>>> name=org.apache.commons.logging.impl.Jdk14Logger (avail_mem=819540K)
>>>>>      [java] [3.243s][debug][redefine,class,load        ] loading 
>>>>> name=org.apache.commons.logging.impl.Log4JLogger kind=101 
>>>>> (avail_mem=819540K)
>>>>>      [java] [3.244s][info ][redefine,class,load,exceptions] 
>>>>> link_class exception: 'java/lang/NoClassDefFoundError 
>>>>> org/apache/log4j/Priority'
>>>>>      [java] Java Result: 1
>>>>>
>>>>> With 'verification' tag:
>>>>>
>>>>>      [java] [49.702s][info ][verification] Verification for 
>>>>> org.apache.commons.logging.impl.Log4JLogger has exception pending 
>>>>> 'java.lang.NoClassDefFoundError org/apache/log4j/Priority'
>>>>>      [java] [49.702s][info ][verification] End class verification 
>>>>> for: org.apache.commons.logging.impl.Log4JLogger
>>>>>
>>>>>
>>>>> Improved error message:
>>>>>
>>>>>      [java] Exception in thread "main" java.lang.InternalError: 
>>>>> class redefinition failed: invalid class
>>>>>      [java]     at 
>>>>> java.instrument/sun.instrument.InstrumentationImpl.retransformClasses0(Native 
>>>>> Method)
>>>>>      [java]     at 
>>>>> java.instrument/sun.instrument.InstrumentationImpl.retransformClasses(InstrumentationImpl.java:167)
>>>>>      [java]     at Main.main(Unknown Source)
>>>>>
>>>>>
>>>>> Thanks,
>>>>> Poonam
>>>>>
>>>
>>