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

[Harold Seigel]

+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
>>>>
>>
>