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

[serguei.spit...@oracle.com]

Hi Poonam,

Thank you for taking care about this!
It looks good besides the comment from Harold and Coleen about ex_msg can be equal to NULL.

Thanks,
Serguei

On 6/9/20 07:46, 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