code review request for more StringTable verification code (8019835)

[Ron Durbin]

Dan it looks good, 

Thx
Ron

> -----Original Message-----
> From: Daniel D. Daugherty
> Sent: Monday, September 16, 2013 11:48 AM
> To: Serguei Spitsyn
> Cc: serviceability-dev at openjdk.java.net; hotspot-runtime-dev at openjdk.java.net
> Subject: Re: code review request for more StringTable verification code (8019835)
> 
> 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
> >
>