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

[coleen.phillimore at oracle.com]

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
>>>
>