code review request for more StringTable verification code (8019835)

[Daniel D. Daugherty]

Thanks for quick re-review!

Dan


On 9/16/13 11:43 AM, serguei.spitsyn at oracle.com wrote:
> Looks nice.
>
> Thanks,
> Serguei
>
> On 9/16/13 10:08 AM, Daniel D. Daugherty wrote:
>> Greetings,
>>
>> I have some new diagnostic code that I would like to add to the system
>> that was developed during my hunt for this bug:
>>
>>     8019835 Strings interned in different threads equal but does not ==
>>     http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8019835
>>     https://bugs.openjdk.java.net/browse/JDK-8019835
>>
>> Here is the third round HSX-25 webrev URL:
>>
>> OpenJDK: http://cr.openjdk.java.net/~dcubed/8019835-webrev/2-hsx25/
>> Internal: http://javaweb.us.oracle.com/~ddaugher/8019835-webrev/2-hsx25/
>>
>> This fix was reviewed internally by the following OpenJDK users:
>> rdurbin, sspitsyn, and coleenp.
>>
>> Please note that while this code does detect StringTable corruption
>> due to bad memory, that is not the primary purpose. The primary
>> purpose of the new code is to verify all StringTable invariants.
>>
>> Testing:
>> - JPRT build and test on all platforms with the default value of
>>   -XX:VerifyStringTableAtExit set to true
>> - Aurora Adhoc testing on all platforms with product and fastdebug bits
>>   with the default value of -XX:VerifyStringTableAtExit set to true
>> - Tested on the system with bad memory named in 8019835 and it nicely
>>   shows various types of StringTable corruptions.
>>
>> As always, comments, questions and suggestions are welcome.
>>
>> Dan
>>
>> P.S.
>> Changes between second and third rounds:
>> - removed the redundant code in compare_entries() that Coleen spotted
>>
>> Changes between first and second rounds:
>> - add missing String oop check to StringTable::compare_entries(); only
>>   comes into play when an error happens
>> - add mesg_mode parameter to verify_entry() to clarify when we should
>>   be supressing duplicate error messages
>> - refactor StringTable::verify_and_compare_entries() into two phases
>>   for clarity:
>> - phase 1 verifies all entries in the StringTable
>> - phase 2 compares all entries in the StringTable
>