JVM/TI code review request (XS and M) (7182152)

Daniel D. Daugherty daniel.daugherty at oracle.com
Mon Feb 4 13:08:06 PST 2013


I've updated the fix due to comments in Code Review Round 0.

Here is a summary of changes made to the various files:

src/share/vm/oops/cpCacheOop.cpp (HSX-23.6, HSX-24)
src/share/vm/oops/cpCache.cpp (HSX-25)
   - removed the new RC_TRACE_NO_CR() macro calls at Coleen's request;
     these files are outside of JVM/TI RedefineClasses proper so the
     tracing/debug style should not be dictated by JVM/TI RedefineClasses
     style that is currently in use
   - did not touch the existing RC_TRACE... macros in the file; removing
     the existing macro calls would be outside the scope of this bug

src/share/vm/oops/cpCacheOop.cpp (HSX-23.6, HSX-24)
src/share/vm/oops/cpCache.cpp (HSX-25)
   - copy a comment from 
     to ConstantPoolCacheEntry::check_no_old_or_obsolete_entries()

   - Copied the new comment intended to prevent the "break" from
     re-materializing again from klassItable::adjust_method_entries()
     to klassVtable::adjust_method_entries(); yes, I'm paranoid.

In the HSX-25 version only:
   - revert changes

   - wrap uses of is_valid() in NOT_PRODUCT macro as appropriate

Here are the URLs for the updated webrevs:


The JPDA stack testing that I started on Friday is still running on
WinXP so I'm blocked for checking the recompile due to these changes.
I'll start a recompile on Solaris X86, but that will take some time.

Thanks, in advance, for more comments, suggestions or questions.


On 2/1/13 12:55 PM, Daniel D. Daugherty wrote:
> Greetings,
> I have a fix for the following JVM/TI bug:
>     7182152 Instrumentation hot swap test incorrect monitor count
>     http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7182152
>     https://jbs.oracle.com/bugs/browse/JDK-7182152
> The fix for the bug in the product code is one line:
> src/share/vm/oops/klassVtable.cpp:
> @@ -992,18 +1020,50 @@
>            // RC_TRACE macro has an embedded ResourceMark
>            RC_TRACE(0x00200000, ("itable method update: %s(%s)",
>              new_method->name()->as_C_string(),
>              new_method->signature()->as_C_string()));
>          }
> -        break;
> +        // cannot 'break' here; see for-loop comment above.
>        }
>        ime++;
>      }
>    }
>  }
> and is applicable to JDK7u10/HSX-23.6 and JDK7u14/HSX-24. Coleen
> already fixed the bug as part of the Perm Gen Removal (PGR) project
> in HSX-25. Yes, we found a 1-line bug fix buried in the monster PGR
> changeset. Many thanks to Coleen for her help in this bug hunt!
> The rest of the code in the webrevs are:
> - additional JVM/TI tracing code backported from Coleen's PGR changeset
> - additional JVM/TI tracing code added by me and forward ported to HSX-25
> - a new -XX:TraceRedefineClasses=16384 flag value for finding these
>   elusive old or obsolete methods
> - exposure of some printing code to the PRODUCT build so that the new
>   tracing is available in a PRODUCT build
> You might be wondering why the new tracing code is exposed in a PRODUCT
> build. Well, it appears that more and more PRODUCT bits deployments are
> using JVM/TI RedefineClasses() and/or RetransformClasses() at run-time
> to instrument their systems. This bug (7182152) was only intermittently
> reproducible in the WLS environment in which it occurred so I made the
> tracing available in a PRODUCT build to assist in the hunt.
> Raj from the WLS team has also verified that the HSX-23.6 version of
> fix resolves the issue in his environment. Thanks Raj!
> Here are the URLs for the three webrevs:
> http://cr.openjdk.java.net/~dcubed/7182152-webrev/0-hsx23.6/
> http://cr.openjdk.java.net/~dcubed/7182152-webrev/0-hsx24/
> http://cr.openjdk.java.net/~dcubed/7182152-webrev/0-hsx25/
> I have run the following test suites from the JPDA stack on the
> JDK7u10/HSX-23.6 version of the fix with -XX:TraceRedefineClasses=16384
> specified:
>     sdk-jdi
>     sdk-jdi_closed
>     sdk-jli
>     vm-heapdump
>     vm-hprof
>     vm-jdb
>     vm-jdi
>     vm-jdwp
>     vm-jvmti
>     vm-sajdi
> The tested configs are:
>     {Solaris-X86, WinXP}
>       X {Client VM, Server VM}
>       X {-Xmixed, -Xcomp}
>       X {product, fastdebug}
> With the 1-liner fix in place, the new tracing code does not find any
> instances of this failure mode in any of the above test suites. Without
> the the 1-liner fix in place, the new tracing code finds one instance
> of this failure mode in the above test suites:
>     test/java/lang/instrument/IsModifiableClassAgent.java
> There are two new tests that will be pushed to the JDK repos using
> a different bug ID (not yet filed):
>     test/com/sun/jdi/RedefineAbstractClass.sh
> test/java/lang/instrument/RedefineSubclassWithTwoInterfaces.sh
> There will be a separate review request for the new tests.
> I'm currently running the JPDA stack of tests on the JDK7u14/HSX-24
> and JDK8-B75/HSX-25 versions of the fix. That testing will likely
> take all weekend to complete.
> Thanks, in advance, for any comments and/or suggestions.
> Dan

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